Episode 2 – essential fatty acids, fish & fish oil

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In this second podcast episode I cover the basics of essential fatty acids, discuss the importance of reducing intake of omega-6 and increasing intake of omega-3, and compare the relative benefits of fish vs. fish oil as sources of omega-3.

I go through most of the material I’ve written about in my special report on essential fatty acids, fish and fish oil, but there is some additional material in the podcast that isn’t in the written series.

I’ve also answered a few of the most common questions that came up in the comments section, or were emailed to me by readers.

Topics include:

  • Why flax oil isn’t an adequate source of omega-3 fats
  • The importance of reducing omega-6 consumption
  • How much omega-3 is enough to prevent disease and promote health
  • The advantages and disadvantages of fish vs. fish oil as sources of omega-3
  • Criteria for choosing a fish oil
  • Is vitamin A safe in cod liver oil?
  • Is EPA or DHA more important in human health?

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Full Text Transcript

Hey everyone, it’s Chris Kresser from TheHealthySkeptic.org, and welcome to the second Healthy Skeptic podcast.  Today I’m gonna talk about the recent series I published on my blog about essential fatty acids and fish oil.  I realize not everyone has time to read a series like that, and a podcast is a good way to get basic ideas across and just another way for the information to sink in.  I also want to take the opportunity to answer some questions that were posted in the comments section of some of the articles in the series, and I’ve added some new materials so those of you who have already read the series don’t get too bored listening to the podcast.  And for those of you who are hearing this podcast who haven’t read the series, it’s on my blog at TheHealthySkeptic.org/EssentialFattyAcids.

So, most relatively health-conscious people have heard of omega-3 and omega-6 fats by now.  Most people know that omega-3’s protect against several different diseases like cardiovascular disease and all kinds of inflammatory conditions, and most people know that if they’re eating a standard American diet or even a fairly healthy diet, they’re probably not getting enough omega-3’s.  But what many aren’t aware of is that omega-6 fatty acids have nearly the opposite effect to omega-3’s.  They promote inflammation; they contribute to several different modern diseases like heart disease, obesity, and diabetes; and unfortunately omega-6 fats have become ubiquitous in the modern diet.  Pretty much all processed, refined, and restaurant-cooked foods have omega-6 fats in them, and up to 20% of calories in the average American person’s diet are made up of omega-6 fats.  So, I’m gonna start by explaining the basics of omega-3 and omega-6 and how they’re metabolized in the body, the role they play in health and disease, where they’re found in the diet, and how much of each that we need, and then I’m talk about fish as a source of omega-3 and explain why fish is superior as a source of omega-3 to plant-based sources like flax oil and walnuts, and I’m gonna address concerns that people have about the safety of fish consumption.  After that, I’ll talk about fish oil as a source of omega-3.  Fish oils, of course, have become wildly popular in the past decade.  This is partly because of concerns about the safety of eating whole fish, and unfortunately, even as these oils have become so popular, what most people don’t understand is that not all fish oils are created equal.  Many are made with poor ingredients, and they’re too low in EPA and DHA, which are the long-chain omega-3 fatty acids, to have a therapeutic effect.  So, I’m gonna summarize some criteria for choosing a good fish oil if you decide to take fish oil.  And finally, I’ll finish up by answering a few of the questions that I received that I think would be of interest to people listening to the podcast.

OK, so let’s start with a little bit of biochemistry.  If you don’t understand this, the rest of the series won’t make much sense, so I’m gonna try to break it down and make it as clear and simple as possible.  So, omega-3’s and omega-6’s are fatty acids, and a fatty acid is a chain of carbon, oxygen, and hydrogen atoms with a carboxyl group on the end.  Fatty acids are classified on the basis of how many carbon atoms are in the chain as well as how many double bonds the molecule has.  So, it’s been traditionally believed that there are two essential fatty acids.  One is the omega-3 alpha-linolenic acid, or ALA, which we’ll refer to it as, and the other is omega-6 linoleic acid, or LA.  In this context, essential doesn’t just mean really important.  The technical definition is that the body can’t synthesize it on its own, and that means that we have to get these essential fatty acids from the diet, you know, from foods that we eat.  So, both alpha-linolenic acid and linoleic acid are relatively short-chain fatty acids with 18 carbons.  Each of them is converted through a series of steps into longer-chain fatty acids, and it’s these long-chain omega-3 and omega-6 fats that are then converted into the compounds involved in the inflammatory response.  So, this is important to understand because researchers believe that the majority of the health benefits of omega-3’s come from these long-chain derivatives.  So, examples of long-chain omega-3’s are EPA and DHA, which are the ones that we’ve heard so much about, and long-chain omega-6 is arachidonic acid, of AA.  In foods, the long-chain omegas are only found in animal products and not in plant foods.  This also important to understand as we continue through the podcast.

Why flax oil isn’t an adequate source of omega-3 fats

So, let’s talk more about the omega-3 pathway.  You start with alpha-linolenic acid, or ALA, and this is found primarily in plant foods like flax, chia seed, and hemp seed.  ALA gets converted into stearidonic acid, or SDA, which in turn gets converted into eicosatetraenoic acid, which in turn gets converted into eicosapentaenoic acid, which is EPA, that gets converted into docosapentaenoic acid, which is DPA, and finally into docosahexaenoic acid, which is DHA.  So, that’s quite a mouthful and quite a conversion process there.  In theory, it’s possible to convert ALA, which is the first one that we start with from, you know, flax oil and chia and hemp, into the longer-chain derivatives like EPA, DPA, and DHA.  However, and this is really important to understand, in reality, that conversion process is extremely inefficient.  In fact, healthy humans convert less than 1/2 of 1% of ALA to DHA, and some studies show that conversion is even worse in certain populations, for example, people with nutrient deficiencies.  Studies also show that vegetarians and vegans are notoriously poor converters of ALA to DHA.

So, DHA, as I said before, is exclusively found in animal products.  In this case, it’s seafood and actually also from marine algae, so that’s one vegetarian source of DHA.  So, what this means is that if you’re not eating seafood or marine algae, you’re almost certainly deficient in DHA.  I mean, you could be taking 10 tablespoons of flax oil every day, and because the conversion is so poor, you’re just not gonna be making very much DHA.  So for this reason, some researchers recently have suggested that DHA, and not ALA, is the essential fatty acid in the omega-3 pathway.  And remember, essential means that our body can’t synthesize it on its own and it must be obtained from the diet.  So, there are several lines of evidence that support this.  The DHA content in the tissue of all mammals is similar, despite widely varying intakes of omega-3 fats, and this suggests that DHA is very important, and the body tightly regulates its presence in the tissue.  DHA and the long-chain omega-6 arachidonic acid are the only two omega fats that cross the placenta during pregnancy.  Sixty percent of the dry matter of the brain is fat, and DHA is one of the most abundant fats in the brain.  And the DHA status in newborns is much lower in those receiving formula with short-chain ALA and LA than those receiving formula with preformed DHA, and this, of course, suggests that the conversion of ALA to DHA is poor even in infants.

So, now let’s talk about the omega-6 pathway.  It starts with linoleic acid, or LA, which is found primarily in industrial seed oils like corn, soy, sunflower, safflower, cottonseed, and nuts, and also in the skin and tissue of animals that have been fed these grains, corn and soy, you know, factory-farmed animals.  Particularly pork and chicken tend to have a lot of omega-6 in them these days.  In terms of the conversion process, linoleic acid gets converted into gamma-linolenic acid, which is GLA.  And then that gets converted into dihomo-gamma-linolenic acid, which is DHGLA or sometimes referred to as DGLA, which in turn gets converted into arachidonic acid, which is AA.  GLA is found in evening primose oil, black currant oil, and borage oils, which you might have seen at the health food store; and arachidonic acid, AA, is found in meat, eggs, and dairy products.

OK, so that’s how the short-chain omega-3’s and omega-6 gets converted into the longer-chain omega-3 and omega-6, and what’s important to understand again is that there are several enzymes involved in each step of that conversion process.  Omega-3 and omega-6 actually compete for those same enzymes.  So this means that if you’re eating a lot of omega-6, the conversion of the short-chain omega-6 to long chain will use up those enzymes needed to convert the short-chain omega-3’s into long-chain omega-3’s, so there won’t be enough left over to convert ALA into the longer-chain EPA and DHA.  And studies confirm this.  They show that the higher the omega-6 intake is in the diet, the worse the conversion of ALA to EPA and DHA.

Many of you have heard by now that omega-3 is antiinflammatory and omega-6 is proinflammatory, but let’s look at why that actually is.  As I mentioned before, the long-chain omegas produce compounds involved in the inflammatory response.  These compounds are called prostaglandins, thromboxanes, and leukotrienes.  And what’s crucial to understand is that there are different classes of these compounds that have very different effects.  The long-chain fatty acid omega-6 fat arachidonic acid produces series-2 and series-4 prostaglandins and thromboxanes and series-4 leukotrienes.  Overall, these compounds are proinflammatory.  They promote inflammation.  They’re involved in the activation stage of the inflammatory response.  As a side note, these are the compounds that NSAIDs, or nonsteroidal antiinflammatory drugs, like ibuprofen and aspirin are designed to inhibit.  The enzyme needed to convert arachidonic acid into the inflammatory compounds is called cyclooxygenase, and you might have heard that NSAIDs are COX inhibitors.  What they’re doing is actually inhibiting the conversion of AA to the inflammatory compounds by interrupting that cyclooxygenase or COX enzyme process, so this is why Advil and other NSAIDs can be so effective in relieving inflammation because they prevent the conversion of AA, or arachidonic acid, to those inflammatory compounds, but on the other hand, that’s also why eating foods that are high in omega-6 fats can promote inflammation.

So, what effect do omega-3’s have on inflammation?  The long-chain omega-3 fat EPA produces series-3 prostaglandins and thromboxanes and series-5 leukotrienes.  So, these compounds are far less inflammatory than those produced on the omega-6 side.  DHA produces compounds called docosanoids, and docosanoids are both neuroprotective and antiinflammatory.  It’s one reason why DHA is so good for the brain.  And DHA also inhibits the expression of several inflammatory markers.  We’re still learning about the specifics of this process, but its antiinflammatory effect has been well established in the scientific literature.

So, let’s review what we’ve learned so far.  Traditionally it’s been assumed that there are two essential fatty acids, and those are linoleic acid and alpha-linolenic acid, but recent research suggests that the long-chain DHA and AA, arachidonic acid, and not ALA and LA, may be essential.  Conventional wisdom holds that you can meet your omega-3 needs by eating plant-based omega-3 oils like flax, but again, the research shows that the conversion of ALA to DHA is extremely limited and that especially vegetarians and vegans tend to be deficient in DHA.  Generally speaking, omega-6 are proinflammatory, and omega-3 are antiinflammatory, and I’d like you to keep this last point in mind as we move on to discuss the importance of the omega-6 and omega-3 ratio.

The importance of reducing omega-6 consumption

So, over the course of evolution, there’s been a dramatic change in the ratio of omega-6 to omega-3 fats in the diet.  Throughout 4 to 5 million years of evolution, diets have been relatively abundant in omega-3 and low in omega-6.  Anthropological research suggests that our hunter-gatherer ancestors consumed them in approximately a 1:1 ratio.  This means that our ancestors were eating about the same amount of omega-3 and omega-6 fats.  Both ancient and modern hunter-gatherers are relatively free of modern inflammatory disease, so this is a big clue.  And at the onset of the industrial revolution, there was a huge shift in the consumption of omega-6 and decrease in the consumption of omega-3.  This was caused in part by the advent of the seed oil industry, the corn, soy, cottonseed oils, and the practice of feeding grains to livestock, which raises the amount of omega-6 fats in the tissues of those animals.  In 1935, the ratio of omega-6 to omega-3 was already high at 8.4:1.  Now, remember we’re comparing this to the historical ratio of 1:1.  But between 1935 and 1985, it rose another 23% to 10:1.  And today estimates range from 10:1 to 20:1, with some individuals at high at 25:1.  So that means today people are eating up to 25 times more omega-6 than they have been historically.  So, we just went over how omega-6 and omega-3 compete for the same conversion enzymes, and studies show that the more omega-6 you eat, the higher concentration of omega-6 and the lower the concentration of omega-3 in tissue.  Since omega-6 is proinflammatory and omega-3 is antiinflammatory, it follows that eating a lot of omega-6 and not much omega-3 is gonna increase inflammation.  And on the other hand, the more omega-3 and the less omega-6 you eat, the less inflammation that you’ll have.

So what are the consequences of such a dramatic shift in this historical ratio?  Number one, there’s been a huge increase in all inflammatory diseases, and this is including but not limited to cardiovascular disease, type 2 diabetes, obesity, metabolic syndrome, irritable bowel syndrome, inflammatory bowel disease, rheumatoid arthritis, asthma, cancer — you know, basically any disease that involves inflammation, which is more or less all diseases.  And these are all of the diseases, of course, that are killing us at higher and higher rates every year.  And remember that these diseases were exceedingly rare and, in fact, some of them were completely nonexistent in our hunter-gatherer ancestors and even in modern hunter-and-gatherer populations.  So the association between the rising ratio of omega-6 consumed in the diet and heart disease is particularly striking.  There is a clear straight-line association between the increase in omega-6 intake in existent cultures around the world and the increase in heart disease.

How much omega-3 is enough to prevent disease and promote health

So, people often wonder how much omega-3 they need, but as you can see, the answer to that question depends in large part on how much omega-6 they’re eating in the diet.  The more omega-6 they eat, the more omega-3 they’ll need, and vice versa.  The less omega-6 they eat, the less omega-3 they’ll need.  Unfortunately, most recommendations for omega-3 only focus on increasing omega-3, and they neglect to talk about decreasing the amount of omega-6.  And it’s just not enough for most people to increase the amount of omega-3.  They have to also reduce the omega-6 to get the benefits.  So let’s talk about what might constitute a healthy intake of omega-3’s, and when I say a healthy intake, I mean an intake that reduces your risk for the inflammatory diseases that I just mentioned above.  I’m gonna cut to the chase here.  If you want more detail on how I arrived at these numbers, you can visit the blog and read the articles in the series, and there’s a lot of detail there.  And these recommendations are for someone who’s eating a roughly 2000-calorie diet.  If you make no changes in your omega-6 intake and you assume that you’re eating the US national average of 9% of your calories from omega-6, you’d need a whopping 3.7 grams of EPA and DHA to meet your omega-3 needs.  Now that’s a huge amount.  You’d have to eat 11 ounces of wild salmon every day to get that much.  So, you can see here why it’s important to also reduce omega-6.  So, if you did that, if you reduced your omega-6 intake to approximately 3% of calories instead of 9%, which is the national average, you’d need about 650 mg of EPA and DHA to meet your needs.  That’s approximately three 4-ounce portions of salmon each week, which is a perfectly reasonable amount to eat.  And it doesn’t have to come from salmon.  It could be from sardines or mackerel or other oily fish that are high in EPA and DHA.  Now, reducing omega-6 intake to 3% is easier said than done.  It actually takes a lot of effort.  It means not eating any processed or packaged food at all.  It means limiting restaurant meals because almost all restaurant foods are cooked in these omega-6 oils, industrial seed oils.  And it means cutting back pretty significantly on nuts, which can be a pretty high source of omega-6, and then poultry and pork, especially if they are factory farm poultry and pork.  Of course, if you further limit omega-6, that will further reduce your need for omega-3’s, but as I said, that’s very difficult for most people to do in modern society.

Because limiting omega-6 is so challenging these days even with a low-carb or a paleo/primal-type diet, I do recommend an intake of approximately, I don’t know, close to 1 gram a day of EPA and DHA for most people.  And if they’re dealing with an active inflammatory or autoimmune condition, I think a dosage of 1.5 or even 2 grams a day might be more therapeutic for that population.  Having said that, it’s also wise to be careful of the total amount of these polyunsaturated omega-3 fats that you’re taking in.  I received a question from someone about another blogger who suggests people take up to 20 grams per day of omega-3, depending on their body weight, and the idea is to rapidly replace the omega-6 stored in body tissue with omega-3.  And there’s some logic to this because it does take up to six months to change the fatty acid profile in the tissues.  However, I can’t really endorse this idea.  First, you have to keep in mind that all omega fats, whether you’re talking about omega-3 or omega-6, are highly unsaturated.  That means they’re vulnerable to oxidative damage.  Many fish oils are rancid when they’re sold, and they’re made with poor quality ingredients.  So, of course, most people when they’re advised to take 20 grams a day will just buy the cheapest one available, and that makes sense.  If they’re gonna be taking 20 grams a day of the stuff, it’s not gonna be affordable generally if they get a really high quality oil.  So, my concern is that when people are taking 20 grams of possibly rancid oil or even just polyunsaturated oil that has a high chance of being oxidized in the body, oxidative damage is another risk factor for a number of those modern diseases that I listed before.  So, this is another reason to just limit pretty significantly your omega-6 intake and just moderately increase your omega-3 intake to keep your overall polyunsaturated fat consumption on the relatively low side.

So, now let’s talk about the safety of fish consumption because this is something that’s been a concern for a lot of people.  Many people, especially pregnant women, have actually stopped eating fish entirely.  So let me just summarize the argument of the authorities who advise against eating fish.  They say that fish are full of contaminants like mercury, PCBs, and dioxins and that these contaminants increase the risk of neurological problems and cancer and that pregnant women have been especially warned due to the risk of these contaminants to the developing fetus.  On the other hand, research is very clear that fish consumption protects against disease, everything from cardiovascular disease to autoimmune conditions to cognitive decline.  And cultures that eat a lot of fish have dramatically lower incidence of these conditions.  For example, one study showed that the Japanese, whose consumption of fish is very high, have an incidence of heart disease that’s 87% lower than it is in the US, and the rates of heart disease are even lower than that in Greenland, where the population eats even more fish than Japan.  Basically study after study shows that DHA is essential for proper development of the brain.  The FDA released a report in 2008 that noted that the nutrients in fish, including EPA and DHA, boost IQ levels in kids by up to 10 points, and DHA, when consumed by pregnant women, improves mental processing scores and visual acuity in their babies.

So, how could it be that fish provides so many benefits and are yet so dangerous?  Somebody has to be wrong, and it turns out that those concerned about the safety of fish have been missing a key element in their analysis, and that element is selenium.  It’s true that fish contain a lot of mercury and that mercury can cause serious problems.  However, if you only measure the mercury in fish, it significantly exaggerates the risk because it ignores the protective role of selenium.  Selenium is plentiful in many different ocean fish species, and the public and most health authorities are totally unaware of the protective role that it plays, which I’m gonna explain to you right now.  Selenium has a high binding affinity for mercury.  That means that when selenium and mercury are found together, they connect, forming a new substance, and this new substance makes it hard for the body to absorb mercury separately.  So in other words, when selenium binds to mercury, mercury is not free any longer to bind to anything else, like brain tissue.  There’s a researcher at the University of North Dakota named, I think it’s Richard.  I know his last name is Ralston.  I think it’s Richard Ralston.  And he’s published several papers on the protective effects of selenium.  And I’m gonna let him describe in a conclusion from a recent paper the relationship between selenium and mercury.  So he says:  “Think of dietary selenium as if it were your income and dietary mercury as if it were a bill that you need to pay.  Just as we all need a certain amount of money to cover living expenses such as food and rent, we all need a certain amount of selenium.  Only one major study has shown negative effects from exposure to mercury from seafood, and that seafood was pilot whale meat.  Pilot whale meat is unusual in that it contains more mercury than selenium.  When you eat pilot whale meat, it’s like getting a bill for $400 and a check for less than $100.  If that happens too much, you go bankrupt.  On the other hand, it you eat ocean fish, it’s like getting a check in the mail for $500 and getting a bill for $25.  The more that happens, the happier you are.”

So, what Ralston’s telling us is that as long as the fish we’re eating has more selenium than mercury, there’s nothing to worry about.  And guess which foods are the highest in selenium?  That’s right.  Seafood!  Sixteen of the 25 highest dietary sources of selenium are ocean fish.  And you know, as Ralston said, the few studies that suggested a harmful effect from eating mercury in fish didn’t take selenium into account.  The studies were done in places where fish were consumed that contained more mercury than selenium.  These are fish like pilot whale, tarpon, marlin, swordfish, and some species of shark.  On my blog in the article titled Is eating fish safe?  A lot safer than not eating fish!, I’ve included a chart, which has the mercury and selenium values of various common species of ocean fish.  But I can tell you that most fish that people commonly eat other than ones that I just listed above have more selenium than mercury and are, therefore, completely safe to eat.  Now, other studies have also shown that most freshwater fish have more selenium than mercury.  So if you like to eat trout and other freshwater fish, those are generally safe as well.

So we’ve addressed mercury as a potential safety concern, but what about PCBs and dioxins?  PCBs are synthetic compounds previously used in industrial and commercial processes.  They’re not used much any longer, but they hang around the environment for a long time, so they’re still a problem.  Dioxins are by-products of waste incineration, paper bleaching, pesticide and plastic production.  And the primary concern of both of these is cancer.  Animal studies and limited human evidence have suggested that both are carcinogenic, and of course, it makes sense to avoid these contaminants as much as we possibly can.  But restricting seafood intake, it turns out to be a poor strategy for avoiding PCBs and dioxins.  Why is this?  Because the highest dietary sources of PCBs and dioxins are not fish, but actually meat at 34%, dairy at 30%, and vegetables at 22%.  Fish only constitutes 9% of our dietary intake of PCBs and dioxins.

In a recent analysis of the risk-versus-benefits of seafood comparison, the researchers found that per 100,000 people, farmed salmon resulted in 24 excess cancer deaths, and wild salmon resulted in an excess of 8 cancer deaths.  Now that might sound like a big deal, but the other side of it is that consumption of both farmed and wild salmon resulted in over 7000 fewer coronary heart disease deaths.  In another analysis of that same data, the heart disease benefits outweighed the potential cancer risk by 100 to 370 times in farmed salmon and by 300 to 1000 times in wild salmon.  But cancer estimates in this study assumed a lifetime salmon consumption of four 6-ounce servings of wild salmon every week for 70 years.  Now, that’s a really large amount of salmon.  Almost nobody in the US eats that much.  But on the other hand, reduction in heart disease deaths from fish could be achieved by a much lower intake than four 6-ounce servings every week.  Just one 6-ounce serving of wild salmon would provide the same heart disease benefit, meaning over 7000 fewer heart disease deaths per 100,000 people, while at the same time reducing cancer risk by 75%, which would bring down the estimated cancer deaths to 6 excess deaths for farmed salmon per 100,000 and 2 excess deaths from eating wild salmon per 100,000.  So when you put all that together, what this means is that the heart disease benefits of eating one 6-ounce portion of wild salmon each week outweigh any potential cancer risk by more than 3500-fold.  So, it’s just really difficult to make an argument that PCBs and dioxins pose any kind of significant risk, and it’s very clear that the benefits of eating fish far outweigh any potential risk that PCBs and dioxins might pose.

So let’s pause and take a moment to review before we go on.  I’m gonna have another sip of water here.  So selenium protects against mercury toxicity, as we’ve just discussed, and if a fish has more selenium than mercury, it’s safe to eat.  Most species of commonly eaten fish in the US, whether you’re talking about freshwater or ocean fish, have more selenium than mercury.  Fish are not significant sources of PCBs and dioxins when compared to meat, dairy, or vegetables.  And the benefits of eating fish far outweigh the risks, in fact, by up to 3500-fold.

The advantages and disadvantages of fish vs. fish oil as sources of omega-3

So now we know how important long-chain omega-3’s like EPA and DHA are.  Next we’re gonna talk about whether fish or fish oil is a better source of these long-chain omega-3’s.  Most people have turned to fish oil due to concerns about the safety of eating fish, but now that we know that fish are safe to eat, this question of fish versus fish oil becomes more relevant.  We’re going to evaluate this question based on a few criteria.  The first is nutrient content.  Whole fish are not just little swimming sacks of DHA and EPA.  They’ve got other nutrients as well, like vitamin D, selenium, really high quality protein, cofactors needed for the absorption of these nutrients, and a more complete fatty acid profile than fish oil.  Selenium, as we’ve just explored, is particularly important because it protects against mercury toxicity.  Vitamin D, as I’m sure you are well aware, is crucial and protects against many of the same modern diseases that we’ve talked about in this podcast.  And many people are deficient in vitamin D these days, particularly people living in relatively northern or southern latitudes.  And most fish contain only EPA and DHA, though some, like cod liver oil and wild salmon oil, have moderate amounts of vitamin D and other fat-soluble vitamins.

So the second criterion is potency.  And when I say potency, we’re basically talking about how much EPA and DHA is present in the product or the fish.  A 6-ounce serving of wild salmon has 880 mg approximately of EPA and about 1100 mg, or 1.1 gram, of DHA.  And according to those amounts, approximately two to three 6-ounce servings a week and then lowering your intake of omega-6 to about 3% of calories would be adequate for most people.  But fish oil may have an advantage here in the potency category.  Because the fish oils are molecularly distilled and purified, the DHA and EPA content can be much higher than it is in fish.  Six capsules of a product called Jarrow Max DHA would provide 1.5 grams of DHA each day, which is really difficult to obtain from fish unless you’re eating a lot of it.  To get that same 1.5 grams-per-day dose of DHA, you’d have to eat about 9 ounces of wild salmon every day, and that’s just gonna be out of most people’s price range and comfort zone.

The third criterion is absorption, and this is where things get a little bit tricky.  Again, I’m gonna summarize here.  If you want more information on this, see The fish vs. fish oil smackdown article on my blog.  EPA and especially DHA are much better absorbed from fish than fish oil, and the effect may be as great at nine-fold.  So this means we need to take nine times more DHA from fish oil to get the same amount of DHA from fish.  On the other hand, taking fish oil capsules with a high-fat meal improves the absorption of fish oil significantly.  This is something that I’ve almost never heard in the media or from any healthcare practitioners, but there are at least four studies that show this in the literature.  So, if you are taking fish oil capsules or just fish oil in the liquid form, it’s really important that you take your fish oil with a high-fat meal and that will dramatically improve the absorption.  It may even put fish oil on par with whole fish in terms of absorption, but I say “may” because the scientific literature is kind of mixed on this question.

So the fourth criterion is cost, and it’s tricky to compare because prices and availability of fish and fish oil vary regionally depending on where you live, and again, I’ll cut to the chase here.  There’s a lot more detail on my blog in The fish vs. fish oil smackdown article.  To obtain 500 mg a day, or half a gram a day, from salmon, assuming a cost of $13 per pound, would cost about $15.50 per week.  Now, to obtain that same amount, 500 mg per day, from Jarrow Max DHA, assuming you bought it from Vitacost at a cost of around $15 a bottle, that would only cost you $1.14 per week to get that same 500 mg per day dose.  So, obviously the fish oil is dramatically cheaper, but there are a few caveats to this.  The first is that, as I said above, it’s uncertain whether even with a high fat meal absorption of the DHA and EPA of these oils, these refined oils, would be the same as it is from the fish.  Number two, salmon has large amounts of high quality protein, selenium, vitamin D, and other nutrients that the fish oils doesn’t have.  And number three, there are other oily fish like sardines and mackerel that are very high in EPA and DHA that are much cheaper than wild salmon, so the difference between the cost of fish and fish oil if you’re eating sardines and mackerel instead of salmon, or maybe in addition to salmon, wouldn’t be quite as dramatic.

The fifth criterion is environmental impact, and as most people know nowadays, overfishing and fish farming has seriously damaged the health of marine ecosystems around the world.  A lot has been written about this elsewhere, so I’m not gonna spend too much time.  I will say that my favorite book on the subject, which was recommended by a Healthy Skeptic reader — thanks for that — is called The End of the Line:  How Overfishing is Changing the World and What We Eat by Charles Clover, and I suggest if you’re interested in this issue, which I hope you are, you read that book.  But I’ll summarize the recommendations here:  I think the most responsible choice is to eat only fish that are certified by groups like the Marine Stewardship Council.  It’s important to realize that even those groups aren’t infallible, so it’s good to do your own research and stay abreast of changing policies and practices.  But in general, most environmentalists and scientists support the MSC certification, Marine Stewardship Council, and it’s, in general, a good guideline to go by.  You can visit their website.  Just Google the Marine Stewardship Council, and it has a list of fish that they consider sustainable and safe to eat.

So, what’s the verdict in the fish vs. fish oil smackdown?  It’s not so easy to say.  It’s a complicated question and it depends on several different factors, for example, whether you need DHA for maintenance or for a therapeutic effect, what your current DHA status is, you know, are you deficit or do you have relatively good levels?  What are your financial considerations?  Do you have access to sustainably caught fish?  Are you looking for the other nutrients that you can get from fish, like vitamin D and selenium?  So I’m gonna break down recommendations into a couple just loose general categories.  For people who are generally healthy, I recommend reducing omega-6 significantly to around 3% of calories if you haven’t already, and then eating a moderate amount of oily fish each week like sardines or mackerel or salmon.  Two to three 6-ounce servings is a good amount to aim for, and this should give you plenty of EPA and DHA along with high quality protein, selenium, and vitamin D.  And if wild salmon is out of your price range, as I said before, mackerel and sardines are both high in EPA and DHA and are also MSC certified, so those are good options.  Those with chronic inflammatory conditions like heart disease or an autoimmune disorder, I recommend a combination of whole fish, perhaps the same above, two to three 6-ounce servings a week, plus a high-quality fish oil.  So this ensures that you’re getting the benefits of whole fish along with the added therapeutic effect of high-dose DHA and EPA.  So somewhere around 1.5 grams of DHA each day would be a good dose to aim for, so this means getting about 1 gram from fish oil in addition to 500 grams a day from fish, which you would get from eating those three 6-ounce portions of fish per week.

Criteria for choosing a fish oil

Finally, I’m gonna talk about how to choose a fish oil, because this is a subject that there’s a lot of misunderstanding and confusion about, and it’s a big subject.  I’ve written a really long article about it with a lot of detail on my blog.  It’s called The definitive fish oil buyer’s guide, and again here I’m just gonna summarize the issues, and you can read the article if you want more detail.  So first, I just want to mention again that not all fish oils are created equal.  There’s a huge variation in the quality of products on the market, and the supplement industry is rife with false claims and unsavory companies who are way more interested in profiting from the fish oil craze than they are in your health and well-being.  Many of the products out there are made with poor quality ingredients and may have higher-than-safe levels of toxins, they may be rancid or oxidized, so it’s really, really important that you do your homework before choosing an oil for yourself and for your family.  And again, there are several criteria to consider.  Purity is the first.  The oil should meet international standards that have been set for heavy metal, PCB, and dioxin content and other contaminants.  A lot of these oils that are sold in supermarkets don’t meet those international standards even when they claim they do.  In fact, there was a recent lawsuit about this in California.  Or they may not even list the heavy metal, PCB, and dioxin content, and when you ask them for a certificate of analysis, which is an independent analysis performed by an outside laboratory that verifies their claims, they won’t give it to you.  I start to get really suspicious if a company won’t give me a certificate of analysis, or a COA, so that’s something you should always ask the manufacturer for before you decide to buy an oil from them.

In terms of freshness, fish oil is susceptible to oxidative damage, as I said before, because it’s made up of highly unsaturated fatty acids.  Oxidative damage, the term you might know for this is “rancid.”  These rancid oils will wreak havoc in the body.  As I said before, oxidative damage is a major risk factor for several different modern diseases, and if you’re taking rancid oils on a regular basis, you’re gonna get basically the opposite of the desired effect.  Potency is the third criterion.  To have the antiinflammatory effect, the fish oil must have an adequate level of DHA and EPA.  Most of them do, but some of them don’t.  Particularly if you’re going for 1.5 grams of DHA, that can be pretty hard to get from some of the oils on the market that have low amounts of DHA.  Fourth criterion is nutrients.  All fish oil contain some amount of EPA and DHA, but fish liver oils like cod and skate liver and also wild salmon oil contain, in addition to EPA, some naturally occurring fat-soluble vitamins like vitamin D, vitamin K2 in the case of the fermented cod liver oil, and vitamin A.

Bioavailability is the fifth criterion, and what we’re talking about here is the absorption of different types of oil.  And actually in the same way that fish is better is better absorbed than fish oil in general, natural fish oils, the natural triglyceride fish oils, are better absorbed than the highly purified and molecularly distilled fish oils.  This is important to keep in mind when you’re choosing an oil because even if the dosages of DHA and EPA are higher in the refined oils than the natural oils, it doesn’t necessarily mean that you’ll be absorbing more of the EPA and the DHA from those products.  And there’s some evidence that krill oil, which we’ll talk about below, is better absorbed than fish oils.  OK, the sixth criterion is sustainability, and again here we just want to make sure that the fish that the oil is made from are harvested in a sustainable manner.  The sustainability of fish oil is a little bit more complex even than the sustainability of fish.  I’ve written a little bit about it on my blog, but that’s the main point is that the fish that the oil is made from should be ones that are certified by the Marine Stewardship Council.  And finally, we have cost.  In order for fish oil to be practical for people, it has to be affordable.

Based on these criteria, I can make a few recommendations.  What you choose here, again, depends on your goals.  I’m gonna include two basic categories for supplementation.  One is baseline, and the other is supplemental.  And baseline is for maintenance and ensuring adequate nutrient intake.  I recommend one of these baseline products for everybody, for people in good health and people who are dealing with a chronic health challenge.  Supplemental is an oil you could take in addition to baseline if you’re dealing with an inflammatory disease or any kind of a chronic health challenge.  The two baseline products that I recommend, the first one is Green Pasture Fermented Cod Liver Oil.  This is really more of a whole-food product than a supplement.  It contains EPA and DHA in moderate amounts, but it also contains high amounts of natural vitamin D, natural vitamin A, and vitamin K2, which is a vitamin a lot of people haven’t heard of.  It was only relatively recently discovered, but it turns out to play a really important role in cardiovascular disease.  It regulates calcium metabolism and ensures that calcium is deposited in the bones and the teeth where it belongs and not in the soft tissues like the arteries, and there’s just a low of research showing that K2 is really important in preventing cardiovascular disease and that most people, most North Americans and Europeans are deficient in K2 because there aren’t very many foods that are commonly eaten that K2 is in.  So this is one significant reason that I like the fermented cod liver oil.  The other reason is that the fermented cod liver oil is cold-processed through fermentation, so it’s not heated, and remember before that these oils are highly unsaturated and any time you apply heat to highly unsaturated oil you have an increased risk of oxidation occurring.  So when the oil is fermented and cold-processed, it’s much less likely that it will be oxidized or damaged by the heat.  There aren’t very many oils on the market that are cold-processed like this, and the fermented cod liver oil is one of them.  The second baseline product I like, Vital Choice is the company, and it’s their Wild Salmon Oil.  This is MSC certified, and it has moderate amounts of EPA and DHA along with a pretty good amount of natural vitamin A and D.  It’s also processed without heat using microfiltration.  The fatty acids are in their natural triglyceride form, which means they’ll be better absorbed than the highly purified and refined oils, and salmon are naturally low in contaminants like PCBs and dioxin and mercury, so the Vital Choice product meets all of the international standards.

So there are two supplemental products.  Of course, there are many more products than I’m talking about here.  I’m just giving you recommendations based on my research and hopefully also giving you the criteria that you need to make your own decision and identify products that are a good choice for you.  In the supplemental category, one that I’m familiar with is called Jarrow Max DHA.  Jarrow is a pretty good company.  I’ve had some success with their products in the past even though I’m not generally a big fan of supplements.  Jarrow has been around for a long time, and they have a pretty good reputation in the industry.  As I mentioned above, it’s pretty cheap.  You can get 1 gram per day of DHA for just $0.32.  It’s made with anchovies and sardines, both of which are naturally low in contaminants because they’re pretty low on the food chain and they don’t concentrate the mercury and PCB and dioxins like the predatory fish.  And I did get a certificate of analysis faxed to me by Jarrow.  They did it right away, and everything checks out, so I also liked that they were very forthcoming with that.

The other supplemental product I’m gonna mention is called V-Pure Vegetarian DHA.  Now, I bring this up because I got some emails from vegetarian readers of my blog asking what they could do to boost their DHA status because most DHA that we get in the diet comes from seafood.  Now, this DHA product is made from marine algae, which is actually where the fish get their DHA from, and marine algae DHA is the only DHA that’s approved for use in baby formula, so it has a history of use, and I don’t have any personal experience using it or working with it, but it’s the only vegetarian source of DHA and EPA I’m aware of.  It does have a whole lot more DHA than EPA, a 7:1 ratio, which by the way, the Jarrow Max product is also a 7:1 DHA to EPA ratio.  This isn’t a problem from my perspective because I tend to think that DHA is more important than EPA, and I’ll address that.  That’s actually one of the reader questions I’m gonna address at the end of the podcast.  The problem with the V-Pure product is that it’s very expensive.  To get that same 1 gram per day of DHA would cost a little over $100 a month.  So unfortunately if you’re a vegetarian and you do want to boost your DHA status, you’re gonna have to pay for it.  Maybe someone could write in if they have a cheaper source of this product.  I was just going on the price that I could find listed on their website, so please let us know if you have a cheaper source of the V-Pure DHA or another company that maybe makes an equivalent product that’s a little bit cheaper.

So now let’s finish up the fish oil discussion by talking about krill oil.  Now, krill oil is a relatively new product on the scene.  It’s not technically a fish oil because it’s made from krill, which is a crustacean.  And krill oil is different than fish oils in that it has a unique phospholipid structure that appears to improve the absorption of EPA and DHA.  Normally when you take fish oil, the EPA and DHA come in triglycerides, and in krill oil the EPA and DHA are incorporated into phospholipid, and since in our bodies eventually we want to get the EPA and DHA into the phospholipid, there’s some research that suggests that the phospholipid structure of krill oil facilitates transfer across the intestinal wall and improves the absorption of krill oil when compared to fish oil.  So krill oil also contains vitamins E and A as well as astaxanthin, which is very potent antioxidant at least in vitro.  We don’t have a lot of scientific literature on the effect of astaxanthin in humans, but certainly the astaxanthin could at least protect the krill oil from oxidation, which is important, as we’ve discussed.  There’s some limited research that suggests that krill oil may have a greater antiinflammatory effect than fish oil.  I did see one study suggesting this.  There’s one study that suggests that it has quite a dramatically superior effect on blood lipids like cholesterol and triglycerides and blood glucose when compared to fish oil, and I wrote about this extensively in The definitive fish oil buyer’s guide, so if you want more information on that, check out that article.  And then I’ve received a lot of anecdotal reports both from patients that I’ve treated and then people sending in comments to the blog suggesting that they do a lot better with krill oil than fish oil.  It doesn’t give them the burps that people get from fish oil; it has a better antiinflammatory effect.  On the other hand, some people seem to do better with fish oil, so I’m not sure what’s happening there, but if fish oil isn’t working for you or you’re just starting out with this, you might want to try krill oil for a week and then try fish oil for a week and see what happens.

I will say that there are comparatively very few studies on krill oil compared to fish oil, which has just been extensively studied over the past couple of decades, and most of the few studies that have been done on krill oil have been sponsored by Neptune Technologies, which is the company that produces most of the krill oil.  And being the healthy skeptic that I am, even if those studies are well designed and everything seems OK on the surface, I just get a little bit skeptical and wary when the study is sponsored by the company that’s manufacturing the product.  The other thing is that the sustainability of krill oil seems to be really controversial.  I’ve read several arguments suggesting that krill harvest is a problem and damaging, the krill populations are threatened by this, and since krill is at the very bottom of the ocean food chain, if krill becomes a problem, then it would affect every single species, you know, nearly every species of fish in the ocean.  And then I’ve read several different arguments suggesting that krill is healthy and that the amount of krill oil that’s being harvested isn’t a problem.  So I frankly have not come to any kind of clarity on this situation myself.  If any of you have information one way or the other that you want to share, I’d appreciate that, and I can post it to the comments section of the podcast so that we have a better idea of what the situation is from a sustainability standpoint with krill oil.

OK, so that’s the end of what I’ve presented for the podcast or what I had to present in the podcast, and now I’m just gonna answer a couple of questions from readers that tend to come up a lot and I think a lot of people are interested in.

Is EPA or DHA more important in human health?

So the first question is whether DHA or EPA is more important, meaning is it DHA that’s having the antiinflammatory effect and producing all of the cardiovascular benefits, or is it EPA?  So I’m gonna say right up front that the literature is mixed on this.  I don’t know for sure what the answer is.  I don’t know that anyone knows for sure.  But having said that, what I’ve read recently suggests that DHA may be more important than EPA, and I’m gonna share several lines of evidence that led me to that conclusion, and I’m just gonna provide the caveat again that I completely reserve the right to change my mind on this.  But here it goes.  Here’s what convinced me, and maybe it’ll convince you:  First, the evolution of the brain and the nervous system originated in a marine environment, which had a rich supply of DHA.  Sixty percent of the brain is fat, and DHA is one of the major fatty acids in the brain.  DHA is a major component of fatty acids in neural cell membranes in 42 different mammals that have been studied.  DHA is superior to EPA in inhibiting the expression of various inflammatory markers.  There’s a lot of data now that demonstrates that DHA has important hemodynamic and antiatherogenic properties.  This means that it promotes proper blood flow and protects against heart disease.  DHA, but not EPA, increases HDL and increases LDL particle size, both of which are protective factors against heart disease.  DHA, but not EPA, can also significantly reduce heart rate, blood pressure, and platelet aggregation.  So there are more, but those are a few lines of evidence that suggest that DHA may be important, but I’m not sure enough about this to say that we should only get DHA from EPA, and of course, if you eat whole fish, they have both DHA and EPA, which to me suggests that they both probably play a role, and it’s a good idea for us to get both.  But if you’re choosing a fish oil, my tendency would be to choose one that has more DHA than EPA.

Is vitamin A safe in cod liver oil?

OK, second question is — and I received probably at least six or seven emails with the same question or comment on the blog because the Vitamin D Council has recently come out saying that vitamin A is toxic and that people shouldn’t take cod liver oil.  So this is a really contentious issue in the blogosphere right now.  Their argument is basically that vitamin A antagonizes vitamin D and inhibits the absorption of vitamin D and thus reduces the beneficial effects of vitamin D.  And they came to this conclusion by doing studies where they looked at people taking vitamin D, and then they measured the beneficial effects on a certain disease for the people who were taking vitamin D or had a certain vitamin D status, and then they compared the beneficial effects that group had to a group of people that were taking vitamin D and vitamin A at the same time.  And the people who were taking vitamins D and A at the same time had less of a beneficial effect than the people who were taking only vitamin D, so the conclusion that they came to was that vitamin A was somehow getting in the way of vitamin D and decreasing the beneficial effects of it.

Now, it’s true to some degree that vitamin A antagonizes vitamin D and inhibits its absorption, but it’s also true that vitamin A is an important cofactor in the absorption of vitamin D.  And what we always have to remember with these kinds of studies is that prospective studies, or they’re sometimes called epidemiological or observational studies, can only show correlation, not causation.  And the confusion of correlation and causation is what confounded cholesterol research for decades.  For those of you who aren’t familiar with the difference between correlation and causation, we can talk about it for a little bit here.  Maybe the easiest way to explain it is with an example.  So open umbrellas are correlated with rain, which means when it rains, you see a lot of people walking with open umbrellas.  But of course, that doesn’t mean that umbrellas are causing the rain to fall.  In another example, researchers for years saw high cholesterol occurring at the same time as heart disease, and so they assumed that it was the high cholesterol that causes the heart disease, but now we know that that’s actually not true.  It’s not so simple.  So we have to be really careful not to make the same mistake here, confusing correlation and causation.  We see that the higher levels of vitamin A along with the higher levels of vitamin D appeared in a group of people who had a reduced benefit when compared to just high levels of vitamin D, but there’s nothing in these studies that proves that it’s the vitamin A that’s causing that reduction in benefit.  Secondly, there were many other problems with these studies.  For example, in most of them, they didn’t tell us what the source of the vitamin A was in the participants who had higher levels of vitamin A.  Did they get it from food?  Was it from a synthetic supplement?  Did they get it from fortified cereals?  And you know, there’s some evidence that synthetic vitamin A is absorbed and utilized differently than natural vitamin A, so the source of where it’s coming from may make a big difference.

So in situations where there is uncertainty like this in the scientific literature, I think it’s useful to consider the diet of our ancestors.  As we know, they were free of all of these modern diseases that are plaguing us today.  They didn’t have heart disease and autoimmune disease and asthma and allergies like we have today.  So I think it’s useful to consider the kind of foods they were eating and the nutrient content in those foods.  And they ate foods like organs that are high in both vitamin A and vitamin D.  So I think it’s premature to sound the alarm on cod liver oil and other nutrient-dense foods that contain vitamin A based on some prospective observational studies.  I think we need randomized clinical trials where you take, you know, two groups of people and you give them both vitamin D and then you give the second group vitamin A along with that vitamin D from one consistent, whole-food-based source, and then you compare what happens in those groups over a period of time.  That’s the only way we’re really gonna know the answer to this question.  And considering that many, many healthy traditional cultures around the world have eaten foods that are naturally high in vitamin A, I’m not worried about it.  I’m not worried about it for my patients, and I think there’s a ton of evidence supporting the health benefits of natural vitamin A in food.

OK, that’s it.  I hope you enjoyed the podcast.  I hope the information was helpful to you.  I hope that it leads to better health for you and your loved ones.  For more information on this topic, you can read the entire series on my blog, which is at TheHealthySkeptic.org/EssentialFattyAcids.  On my blog, on the home page at TheHealthySkeptic.org, you can subscribe to email updates or my RSS feed if you’d like to be notified when I post a new article.  And from the home page on the righthand side in a sidebar, you’ll also see icons for Twitter and Facebook and LinkedIn, and I actually have gotten pretty active on Twitter and Facebook, and I post a lot of just shorter updates with maybe links to articles or, you know, kinda little blurbs of stuff that I’m thinking about that doesn’t ever make it to the blog.  So if you’re on Twitter or Facebook, that’s a good way to keep up with the latest Healthy Skeptic news.  Of course, you’re listening to this already, so I’m assuming you know about the podcast, but there’s an icon there that you can hit to subscribe to the podcast in iTunes.  And keep your eyes out for my first video blog, video podcast, or it’s actually a screencast, to be perfectly accurate.  I’m gonna talk about — Well, the title of it should say it all.  It’s called I have high cholesterol, and I don’t care.  I recently had a very extensive blood lipid panel, and I’m gonna use it as a springboard to talk about which blood lipid markers are important, risk factors for heart disease, and which blood markers are not associated with heart disease.  And you might be surprised.  If you don’t know much about this issue, you might be surprised by the results of that.  So see you next time.  Have a great day or week, and hope to see you soon on the blog.  Bye-bye.

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Comments Join the Conversation

  1. says

    I would recommend you to read the special report Chris Masterjohn (see his blog) wrote on this subject. Like me he thinks we need no more than between 0.5 and 3 grams of the essential fatty acids (omega 3 and omega 6 together) per day. This quantity you can easily get from eating whole foods. Too much of both omega 3 and omega 6 is bad for us. I made a YouTube video about it, you can find it on the CutTheCarb-channel. VBR Hans

  2. Chris Kresser says

    I read Masterjohn’s report when it first came out.  I agree it’s wise to minimize total PUFA, but there’s an enormous amount of evidence suggesting that fish consumption at the levels I outlined is protective against many diseases.

  3. yarrow says

    I have enjoyed both of your podcast so far, so great to absorb this information while doing the dishes.  I have a simple question.  Does the canning process damage Omega 3 fatty acids in fish?  I’ve heard that even cooking salmon at a high temperature can damage these oils.  Thanks for all your research.

    • Chris Kresser says

      That’s a good question. I’m not sure about the canning process, but it’s true that cooking salmon at high temps will oxidize (damage) some of the omega-3 fats. As I mentioned in the podcast, omega-3 fats are highly unsaturated, which makes them vulnerable to oxidative damage.

  4. Moises says

    Chris,
    Thanks for pointing me to the links on Vitamin A’s relation to Vitamin D. This forced me to review the evidence carefully on both sides.
    As the title of your blog suggests, the reasonable approach is to acknowledge that there remains a high degree of uncertainty in this area, and all reasonable people should be willing to keep their minds open to additional data as it arises.
    That said, I find Cannell’s argument more compelling than Masterjohn’s. By the way, this does not mean I uncritically endorse all of Cannell’s views. I believe, for example, that his understanding of what constitutes a healthy human diet is inadequate.
    So, let’s leave the personalities out of this, since that all participants in this dispute are people of integrity.
    The claim that the studies show correlation, not causation, I believe is weak. I can’t disprove it, but the weight of the evidence appears to me to support Cannell.
    You are correct in asserting that Cannell seems only to cite epidemiological studies. And, of course, any particular epidemiological study can only demonstrate the existence of a correlation.
    But what Cannell does is more subtle; he cites multiple epidemiological studies. Essentially, he patches together different studies in order to create a treatment and a control group. But, instead of having a treatment and control group in a single study, he will use one study for the treatment group and the other study as a control.
    Cannell looks at cancers. He finds that in populations where vitamin D is nutritionally available only in combination with vitamin A, high blood levels of vitamin D are associated with high levels of cancer. “Associated” means “is correlated” with. It does not tell us about causation.
    In order to determine causation, we need a control group. Cannell finds such groups in populations where vitamin D is not bound with vitamin A. In these populations high blood levels of vitamin D are not associated with high levels of cancer.
    Group I gets D and A and cancer. Group II gets D alone and does not get cancer. Cannell has cobbled together an interventional meta-analysis.
    Of course, even placebo-controlled interventional studies cannot prove causation. If we are truly sceptics, we must always remain doubtful that all confounding variables have been controlled properly.
    However, my review of the evidence leads me to conclude that I will avoid higher concentrations of vitamin A. I have a lot of respect for the people at Green Pastures, and currently use their X-Factor Butter Oil. I have, in the past, taken their cod liver oil. But, until I see more compelling evidence, I will avoid cod liver oil for the foreseeable future.
    (You might have addressed some of this in your latest podcast, which I have not listened to.)

    • Chris Kresser says

      Moises,

      I’m glad you’re digging into this stuff!

      Holick and Linday were the vitamin D researchers that published the original article on cod liver oil that Cannel commented on, thus starting this whole vitamin A debate. Holick and Linday recently published a rebuttal comment to Cannel in the same journal. I don’t have the full text electronically, but I read it at the medical library.

      Masterjohn wrote a commentary on it here. A few tidbits:

      - The authors pointed out that in Dr. Linday’s randomized, controlled trials, cod liver oil supplementation cut doctor’s visits for upper respiratory infections between one-third and one-half. Cannell’s paper called this “less than robust,” but most of us would consider such a reduction meaningful, especially if it could mean we could get sick half as often by taking cod liver oil!

      - Dr. Linday and her colleagues offer a suggestion: poultry studies suggest optimal A-to-D ratios between four and eight. Similarly, in her own studies showing cod liver oil protects against upper respiratory tract infections, Linday supplied her patients with A-to-D ratios between five and eight.

      - They also point out that rat studies showing that vitamin A is toxic and antagonizes the effects of vitamin D used much higher ratios, ranging from 5,000 to 55,000!

      The ratio of A to D in Green Pastures FCLO is between 2:1 and 3.5:1, well within Linday & colleagues’ recommendation, and far, far below the ratio that proves toxic in animal studies.

  5. Alan says

    Chris,
    I enjoyed your podcast on essential fatty acids. Didn’t have time to read all the posts , but was able to listen to the podcast.
    You mentioned that 0. 5 to 1 percent of ALA (alpha-linolenic acid) will get converted to DHA, not a whole lot.  How much LA (linoleic acid) will get converted to AA (arachadonic acid)? I have this feeling that it is much higher than 1 percent. I didn’t realize until now that AA and DHA are the essential fatty acids!!

  6. Chris Kresser says

    I didn’t come across any exact stats on the conversion of LA to AA, but it in general it is significantly higher than ALA to EPA/DHA.  There are only three steps to convert LA to AA, whereas there are five steps to convert ALA to DHA.  Also, as I mentioned in the podcast, ALA and LA compete for the conversion enzymes and Westerners eat far more LA than ALA.

  7. Moises says

    Chris,
    Thanks to some of your links I have looked into this further. I saw Masterjohn’s journal article abstract. I appreciate all the work you have put into this. The more I look at this, the weaker Cannell’s argument appears to be.
     
    Great stuff!

  8. enliteneer says

    Studies, or stats of any kind, is pretty hard to find for the conversion efficacy of short chain omega-6 to AA…
    But according to this site,
    http://www.fatsoflife.com/omega-6s.php
    it’s less than 0.1%!    Makes you wonder how there is *ANY* inflammation effect from long-chain omega-6s given that low conversion rate!!
     

    • Chris Kresser says

      Take a high quality fish oil along with a high fat meal each day and you’ll get most of the benefits. Make sure you’re getting enough selenium and vitamin D from other sources.

  9. Chris Kresser says

    Yeah, that’s interesting entliteneer.  I guess the eicosanoids produced from AA are extremely potent.

  10. says

    To Mart. A very good way to get a lot of omega 3 is by eating salmon or trout fish eggs. You can buy them in the cooled section of the super market. In my point of view a better, cheaper and more tasteful “supplement” than fish oil. VBR Hans.

  11. says

    Thanks Chris – from your stellar podcast I had by the end of it concluded that this is my best option.
    Hans – just the thought of that makes me gag :)
    Chris: any thoughts on the quality of Puritan fish oil/omega supplements, and/or on Trader Joe’s Omega supplements?
    Off-topic point:
    The trouble with switching to a healthy diet like this, with grass-fed this and wild that is that it ends up very expensive, These are presently luxury items, and I can’t afford anything more than regular supermarket prices, I definitely can’t afford Whole Foods organic prices. I wish there was some guerrilla low-budget way to apply these principles.

  12. Chris Kresser says

    I don’t know that product specifically, but see my Definitive Fish Oil Buyer’s Guide for criteria for choosing a good product.

    I know that some of the grass-fed, organic meat can be expensive.  What we do to reduce the cost is buy directly from a farmer.  For example, we just bought a quarter of a cow from a local ranch.  We got 120 pounds of premium, grass-fed beef for about $5.30/lb.  That’s pretty comparable to grocery store prices, when you consider that the cuts we got include New York steak and filet mignon!

    If you can’t afford grass-fed, try to at least get hormone and antibiotic free.  I believe TJ’s sells that, no?  You can also focus on buying cheaper cuts like brisket, chuck roast, bones, etc. and learning to prepare them.  Those are actually some of my favorite cuts, so no loss there.  There’s a book I love called The River Cottage Meat Book that will help you with this stuff.

  13. enliteneer says

    Just in case anyone is interested in the source for the <.1% conversion for n-6, it appears it comes from this study:
    http://www.jlr.org/cgi/content/full/46/2/269
    Which it of course, has further references:
    “The low long-chain conversion of LA reported here is consistent with results from other human studies (18, 39, 56, 57) and with animal data (51, 58, 59) and reflects the low initial conversion of [13C]LA to [13C]DGLA”
    Thanks to Joyce Nettleton for the link:
    http://www.issfal.org.uk/index.php/pufa-recommendations-mainmenu-146

  14. says

    I feel that flaxseed oil has been treated a little unfairly, as the ALA it contains can heavily contribute to levels of EPA and DHA (long-chain polyunsaturates) in the body.
    Some studies show minimal conversion between ALA and the long-chain omega 3s. Other studies show that men convert 16% of the ALA into long-chain omega 3s while women convert 36%. Other studies show men convert just as well. My experience is that anyone with lipid management problems (high cholesterol etc), chronic disease, nutritional deficiencies or over 50 will struggle with conversion – everyone else is fine.
    In any case, I do test my clients for red blood cell fatty acids so I can measure the difference when I use fish oils and flaxseed oil. I often end up using both.
    (British Journal of Nutrition 2002 Oct;88(4):355-63 Eicosapentaenoic and docosapentaenoic acids are the principal products of alpha-linolenic acid metabolism in young men*. Burdge GC, Jones AE, Wootton SA)

  15. ben says

    Regarding  inflammation…   don’t Long Chain omega-3 *AND* omega-6 PUFAs have pro- and anti-inflammatory properties, depending on the conditions?
    The simplification that omega-6s are pro-inflammatory and omega-3s anti-inflammatory is just that, a gross oversimplification.

  16. Chris Kresser says

    I wouldn’t call it a gross oversimplification at all.  Eicosanoids produced from n-6 are significantly more pro-inflammatory than the n-3 metabolites.  Yes, some n-6 eicosanoids are involved in the resolution stage and are thus not inflammatory, but by and large they are much more inflammatory than n-3.

  17. Tim says

    A great analysis of the Vitamin A issue. I don’t believe Cannell either.
     
    What are your recommendations for a (1 month old or so) baby that is not breast fed? Is there some DHA containing product that is specifically for babies? And should one just put some drops fish oil into the baby formula? Thanks.

  18. Chris Kresser says

    Tim,

    The two most important nutrients a bottle-fed baby isn’t getting are DHA and probiotics.  I can’t stress the importance of either enough.  DHA is usually given in its algae form to babies because of the potential for seafood allergy.  Probiotics should be put in the bottle.  A good multi-species product focusing on low D-lactate species is good at a dose of 50-100 billion CFU.  Prebiotics, especially GOS and beta-glucans, are also important for infants because they promote the growth of species that can’t be supplemented with probiotics.

  19. chuck p says

    Seems whenever there’s too strong of a push in one direction, they’ll be a bounce that will bring it back closer to the middle!
    I’ve seen it with glucasime sulfate (not quite the osteoarthritis cure): http://nutritiondiva.quickanddirtytips.com/do-glucosamine-supplements-work.aspx
    fructose (not quite the villain): http://www.alanaragonblog.com/2010/02/19/a-retrospective-of-the-fructose-alarmism-debate
    vitamin d (not quite the wonder drug): http://phlauntdiabetesupdates.blogspot.com/2010/09/added-new-evidence-that-vitamin-d.html ,
    fat and carbs (see movies: super size me vs. fat-head)
    and now omega-3s:  http://www.ahrq.gov/clinic/epcsums/o3lipidsum.htm
    I guess its best to do your homework and not to think it terms of absolutes, nor in single nutrients!

  20. James G says

    Chris,

    I appreciate the reasoned and sober analysis of the issues addressed in your blog.

    The podcast and articles suggest that omega-3 supplements will be better absorbed by the body when taken along with a high-fat meal. What is an example of a simple, traditional breakfast (that’s when I take my supplement) for a non-vegetarian that is high in the right kinds of fat? Are things like eggs, bacon, or yogurt good, or are they too heavy on omega-6 and trans or saturated fats? Does oatmeal have enough fat?

    Thanks,
    James

  21. Glenn Atkisson says

    Have to agree with Hans Keer’s very first post. Here’s how I see that we have come up with this distortion of logic that has us consuming large quantities of EPA and DHA from fish/krill oil now.

    1. Someone measured the amount of omega-6 and omega-3 being consumed now days, say in the US, and then compared that to the intake in primative cultures, or by other animals. I don’t really know. But it was obvious that a 30 or 40 to 1 ratio of omega-6 to omega-3 was a recent and unhealthy distortion.

    2. Someone decided that its easier to sell a supplement than to get people to stop eating junk food, so we got the omega-3 pitch, big time. Buy fish oil, don’t worry about how tainted the veggie oil is that you’re eating (adulterated omega-6).

    3. Part of the easy way to sell the omega-3 supplements and to interpret the data for what good things omega-3 does is to label omega-6 as “bad”, either because there was too much in the diet, or because the main sources in the diet were adulterated and had become rancid or turned into trans fats by the time they were ingested. Nonetheless, the “too much” and “bad” were not carefully defined, so now the general public interprets this to mean “don’t eat omega-6 at all, definitely don’t take any in a supplement form” but they have no idea how much they are getting because hardly anyone will, in the same sentence say that “commercially ruined vegetable oils are bad, but the human body NEEDS, NEEDS, NEEDS, healthy omega-6 oils the same as ever, and actually more of them than it needs of omega-3′s!” . Nope, we’re on a fever pitch, omega-3 sales binge that won’t stop.

    4. To insure that people were getting their omega-3 from a fish supplement rather than a vegetable supplement, research was turned up that seemed to prove that vegetable sources of true, essential Alpha Linolenic Acid were only spottily converted to the important derivatives, EPA and DHA. So now they’re not happy just pushing omega-3, but the fish oil companies have to see if they can shut out the healthy veggie oil companies from their business.

    Its really about as bad as the deceptive advertising the drug companies are using, once you know the facts.

    If you want a really good discussion on the physiology of essential fatty acids in the human body, go to http://www.brianpeskin.com

    Don’t just read one of Brian’s articles. Read every one and listen to the interviews and watch the lectures. By the time you’re finished, you’ll know a lot more about essential fatty acids than you’ll ever get from reading everything else in the popular press.

    Most everything else you read has come down from the vendors and is half truth.

    For instance, some of the realities are that what has always been described as “essential” is still truly essential. The two essential fatty acids are LA (omega-6) and ALA (omega-3). The derivatives they sell in fish/krill oil are just derivatives that you body can make and has been making for millions of years. The truth is that, no, you body is NOT inefficient at deriving EPA and DHA from ALA (“only a small percent can be converted” is the quote). You body converts what it needs, when it needs it, and INSIDE EACH OF YOUR ten trillion cells. It doesn’t need a lot of DHA and EPA being transported in the blood by overworked cholesterol, only to be dumped somewhere inside cells. There is already a system in place that has always worked just fine at deriving EPA and DHA in the cells when they are needed. Using fish oil to deliver EPH and DHA to cells is a rip off. Think about it. A decade or two of humanity has used fish oil. What did our poor bodies do before the last 20 years?

    Another truth is that not only does your body need omega-6 in a healthy form, but the primary cause of both cancer and heart disease is that the adulterated omega-6 fatty acids that we ingest from commercial vegetable oils and trans fats are taking the place of once healthy omega-6 in our cells, yet are not providing the functionality of healthy omega-6. And its going to take as long as it takes a type of cell to regenerate to get a healthy cell with healthy omega-6 in it, once you get off of junk food and start ingesting healthy omega-6. Several months. Brian Peskin spent a long time analyzing the amounts of all the fatty acids in the different types of human tissue. Only in his documents will you learn how much of each type of essential fatty acid is in each type of human tissue. Just as a tease to read his documents though, the wildest ratio is in human skin, where the amount of LA, or parent omega-6, actually outnumbers the amount of ALA, or parent omega-3, by 1000 to 1. So you can see its a little distorted to tell people very simply “Stop eating omega-6″ and it would be way more responsible to present the whole story, lengthy as it is.

    Stay healthy, stay skeptical and keep researching.

  22. gogogo5 says

    It is precisely posts like the one above from Glenn Atkisson that puts me, your average dude discovering about health and nutrition, into complete disarray.  I have bought into this fish oil supplementation but wonder now if this is wise?

    Please could the so called experts pls chime in and comment on Glenn’s post as I’m becoming skeptical about being skeptical!!!

  23. vlado2020 says

    Say if omega’s are “essential”, how is their deficiency manifested ?
    This article by Ray Peat and a dozen of related links convinced me and taught me of the dangers of omega’s to health.
    http://raypeat.com/articles/articles/fishoil.shtml
    Why do people expect to get health from stinky fish oils and why are people ostensibly promoting unprocessed food promoting ultra processed fish oils? I guess with good marketing some desperate souls will do anything .

  24. Andrew says

    Hi Chris,

    I recently just discovered your website and am enthralled to say the least. I can’t wait to listen to more of your podcasts and read the articles on your blog. I’ve been having health problems for the last few years (am only 26) and actually have a story very similar to yours. I traveled overseas to China and have had chronic issues ever since. Long story short, I have been on the Specific Carbohydrate Diet and have improved quite a bit, but am still a ways off from declaring myself healthy. If I can’t get my health problems within the next few months, you may be hearing from me :).

    Anyway, are you familiar with Carlson Super Omega 3 Fish Oil? It unfortunately does have slightly more EPA than DHA, but I’ve hear and read that it’s considered a really high quality brand. I’d like to get your opinion, though, if possible.

    Thanks for your help.

  25. Will E says

    Have you had a chance yet to reflect on the new research that is claiming that taking fish oil supplements can increase the risk of aggressive prostate cancer by 70%? One article summarizing this study is here:

    http://www.dailymail.co.uk/health/article-2359466/Taking-omega-3-fish-oil-supplements-increase-risk-aggressive-prostate-cancer-70.html

    I am very skeptical of this study at the outset because it appears to be funded by the pharmaceutical industry, and there is clear conflict of interest there. Drug companies want you to be spending thousands of dollars on statins and other super drugs. Moreover, I am put off by the article making claims like fish oil pills are depleting ocean stocks of sharks. This may or may not be true, but why would a true scientist studying the narrow hypothesis of omega3 causing cancer delve into broader topics? Such claims smell of drug companies putting together a hit campaign against fish oils, not true science.

    I did NOT read the original research, but the summary in this article makes me think they measured correlation and had no protocol to measure causation. Look at their claim “However, scientists found that those with the highest levels of omega-3 in their blood were 71 per cent more likely to develop fast-growing, hard-to-treat prostate tumours.” How do we know these aggressive cancers did not themselves cause the accumulation of omega3 into the blood? The claim above does not prove that omega3 itself caused the cancers.

    Would be very interested in your perspective on this research.

  26. Jim Conroy says

    Regarding fish oil. I listened to your podcast Episode 2 and reviewed the written materials on your website. I was disappointed to see that Green Pastures does not list the amount of DHA and EPA amounts. ( I also found a blog (nourished and nurtured at blogspot) that says they will never try fermented fish oil again. I wonder if you have any reaction to their comments.) Finally, the Jarrow claims 7:1 but the label shows more like 3.8:1. Have things changed since you recommended these items?

  27. AJ says

    Thank you for the wonderful insight you have provided for fish oils. I took our advice to check out
    Fish oil JARROW MAX DHA 600mg avail at vitacost but when i checked the site the MAX DHA 600mg is made of calamari oil?
    I checked other related products of Jarrow and found they have Jarrow Formulas EPA DHA Balance® — 120 Softgels

    Fish Oil Concentrate 1100 mg *
    Omega-3 Fatty Acids 600 mg *
    EPA (Eicosapentaenoic acid) 400 mg *
    DHA (Docosahexaenoic acid) 200 mg *
    *Daily value not established.
    Other Ingredients: Fish oil concentrate (Anchovy and Sardine), natural strawberry flavor, and mixed natural tocopherols (from soy). Softgel consists of gelatin, glycerin and water.

    I remembered you mentioned to watch out if gels have flavoring to them? SO is this product not advisable? On the up side theres DHA AND EPA but DHA is 200mg only.

    What are your thoughts on this?

    Thank you!

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