Article summary

• The benefits of fish oil supplementation have been grossly overstated
• Most of the studies showing fish oil benefits are short-term, lasting less than one year
• The only fish oil study lasting more than four years showed an increase in heart disease and sudden death
• Fish oil is highly unstable and vulnerable to oxidative damage
• There’s no evidence that healthy people benefit from fish oil supplementation
• Taking several grams of fish oil per day may be hazardous to your health

A new study was recently published showing that 3g/d of fish oil in patients with metabolic syndrome increased LDL levels and insulin resistance.

Unfortunately, I don’t read Portuguese so I can’t review the full-text. But this study isn’t alone in highlighting the potential risks of high-dose fish oil supplementation. Chris Masterjohn’s latest article on essential fatty acids, Precious yet Perilous, makes a compelling argument that fish oil supplementation – especially over the long-term – is not only not beneficial, but may be harmful.

This may come as a surprise to you, with all of the current media hoopla about the benefits of fish oil supplementation. Yet the vast majority of the studies done that have shown a benefit have been short-term, lasting less than one year. The only trial lasting more than four years, the DART 2 trial, showed that fish oil capsules actually increase the risk of heart disease and sudden death.

A 2004 Cochrane meta-analysis of trials lasting longer than six months suggests that the cardiovascular benefits of fish oil have been dramatically over-stated. They analyzed 79 trials overall, and pooled data from 48 trials that met their criteria. The only effect that could be distinguished from chance was a reduced risk of heart failure. Fish oil provided no reduction in total or cardiovascular mortality.

Too much fish oil can wreak havoc in your body

Omega-3 fatty acids are highly vulnerable to oxidative damage. When fat particles oxidize, they break down into smaller compounds, like malondialdehyde (MDA), that are dangerous because they damage proteins, DNA, and other important cellular structures.

A study by Mata et al demonstrated that oxidative damage increases as intake of omega-3 fat increases. The results of this study were summarized in the Perfect Health Diet, by Paul and Shou-Ching Jaminet:

Notice the clear increase in TBARS (a measure of oxidative damage of the LDL particle) with omega-3 fat. It’s important to note that this was only a 5-week trial. If it had gone on for longer than that, it’s likely the oxidative damage caused by omega-3 fats would have been even worse. This isn’t surprising if you understand the chemical composition of fats. Polyunsaturated fats (PUFA) are highly vulnerable to oxidative damage because they’re the only fatty acids that have two or more double bonds, and it’s the carbon that lies between the double bonds that is vulnerable to oxidation (as shown in the figure below):

Another thing worth noting, if you haven’t already, is that intake of saturated and monounsaturated fats does not increase oxidative damage by a significant amount. This is illustrated in both the table and the diagram above: saturated fats have no double bonds, which means they are well protected against oxidation. MUFA is slightly more vulnerable, since it does have one double bond, but not nearly as much as PUFA which has several double-bonds.

A randomized, double blind, placebo-controlled trial likewise showed that 6 grams per day of fish oil increased lipid peroxides and MDA in healthy men, regardless of whether they were supplemented with 900 IU of vitamin E. And consumption of fresh, non-oxidized DHA and EPA has been shown to increase markers of oxidative stress in rats.

Fish oil not as beneficial as commonly believed

To be fair, at least one review suggests that fish oil supplementation is beneficial in the short and even intermediate term. A recent meta-analysis of 11 trials lasting more than one year found that fish oil reduced the relative risk of cardiovascular death by 13 percent and the relative risk of death from any cause by 8 percent.

But the effect seen in this review was mostly due to the GISSI and DART-1 trials. They found that fish oil may prevent arrhythmia in patients with chronic heart failure and patients who have recently survived a heart attack.

However, there is no evidence that people other than those with arrhythmia and chronic heart failure benefit from taking fish oil or that doses higher than one gram of omega-3 fatty acids per day provide any benefit over smaller doses. And then there’s the rather disturbing result of the DART-2 trial, the only fish oil study lasting more than four years, showing an increase in heart disease and sudden death.

It’s logical to assume the effects of oxidative damage would take a while to manifest, and would increase as time goes on. That’s likely the reason we see some benefit in short- and intermediate-term studies (as n-3 displace n-6 in the tissues), but a declining and even opposite effect in the longer-term DART-2 trial (as increased total PUFA intake causes more oxidative damage).

The danger of reductionist thinking in nutritional research

The current fish oil craze highlights the danger of isolated nutrient studies, which unfortunately is the focus of nutritional research today. Kuipers et al. eloquently described the risks of this approach in a recent paper:

The fish oil fatty acids EPA and DHA (and their derivatives), vitamin D (1,25-dihydroxyvitamin D) and vitamin A (retinoic acid) are examples of nutrients that act in concert, while each of these has multiple actions(7,8).

Consequently, the criteria for establishing optimum nutrient intakes via randomised controlled trials (RCT) with single nutrients at a given dose and with a single end point have serious limitations. They are usually based upon poorly researched dose–response relationships, and typically ignore many possible nutrient interactions and metabolic interrelationships.

For instance, the adequate intake of linoleic acid (LA) to prevent LA deficiency depends on the concurrent intakes of α-linolenic acid (ALA), γ-LA and arachidonic acid (AA). Consequently, the nutritional balance on which our genome evolved is virtually impossible to determine using the reigning paradigm of ‘evidence-based medicine’ with RCT.

Interest in fish oil supplementation started with observations that the Inuit had almost no heart disease. It was assumed their high intake of marine oils produced this benefit. While this may be true, at least in part, what was overlooked is that the Inuit don’t consume marine oils in isolation. They eat them as part of a whole-food diet that also includes other nutrients which may help prevent the oxidative damage that otherwise occurs with such a high intake of fragile, n-3 PUFA.

It’s also important to note that there are many other traditional peoples, such as the Masai, the Tokelau, and the Kitavans, that are virtually free of heart disease but do not consume high amounts of marine oils. What these diets all share in common is not a large intake of omega-3 fats, but instead a complete absence of modern, refined foods.

Eat fish, not fish oil – cod liver oil excepted

That is why the best approach is to dramatically reduce intake of omega-6 fat, found in industrial seed oils and processed and refined foods, and then eat a nutrient-dense, whole-foods based diet that includes fatty fish, shellfish and organ meats. This mimics our ancestral diet and is the safest and most sane approach to meeting our omega-3 needs – which as Chris Masterjohn points out, are much lower than commonly assumed.

Some may ask why I continue to recommend fermented cod liver oil (FCLO), in light of everything I’ve shared in this article. There are a few reasons. First, I view FCLO as primarily a source of fat-soluble vitamins (A, D, K2 and E) – not EPA and DHA. Second, in the context of a nutrient-dense diet that excludes industrial seed oils and refined sugar, and is adequate in vitamin B6, biotin, calcium, magnesium and arachidonic acid, the risk of oxidative damage that may occur with 1g/d of cod liver oils is outweighed by the benefits of the fat-soluble vitamins.

So I still recommend eating fatty fish a couple times per week, and taking cod liver oil daily, presuming your diet is as I described above. What I don’t endorse is taking several grams per day of fish oil, especially for an extended period of time. Unfortunately this advice is becoming more and more common in the nutrition world.

More is not always better, despite our tendency to believe it is.

Summary

Sorry, folks. Another long one. It was unavoidable, though, because I really did want this to be a “definitive guide” that covers all (or at least most) of the relevant issues involved with choosing a fish oil. Here’s a summary for the time-challenged:

• There are seven important factors to consider when choosing a fish oil: purity, freshness, potency, nutrients, bioavailability, sustainability, and cost.
• Not all fish oils are created equal. It’s essential to do your homework and make an informed choice. Many fish oils are oxidized or made with poor quality ingredients, and may actually cause health problems instead of solving them.
• The potency of various products depends not only upon the levels of EPA and DHA, but also upon the molecular structure of the fats in the oil, which in turn affects absorption.
• Natural fish oils are better absorbed than purified fish oils. Preliminary evidence suggests that krill oil (KO) may be better absorbed than fish oil, and anecdotal reports indicate that KO may be more effective for some than fish oil for reducing inflammation in some people.
• Many fish oils are made from fish that are endangered. Choose products made from fish that are certified by organizations such as the Marine Stewardship Council.

Introduction

So far in this series we’ve looked at why fish is superior to plant-based sources of omega-3. We’ve examined the importance of reducing consumption of omega-6 fats. We’ve considered how much omega-3 is needed to support health and treat disease. We’ve revealed that concerns about the safety of fish consumption have been overblown, and that eating fish regularly is not only safe, but incredibly beneficial. And in the previous article we compared the benefits of eating fish to taking fish oil.

In this final article of the series we’re going to take a closer look at fish oil. Fish oil has become wildly popular these days. Most people who are at least relatively health conscious understand that they need omega-3 in their diet, and are probably not getting enough from food (unless they eat a lot of fish).

Health care practitioners have caught on, too. I constantly hear both conventional and alternative practitioners telling their patients to take fish oil. In fact, I was listening to a podcast last week by one popular health and fitness guru in the paleo/primal world, and he advises his clients to take up to 20 grams of fish oil a day. That made me cringe.

Why? Because what most people – including health care practitioners – don’t seem to understand is that not all fish oils are created alike. There’s a tremendous difference in the ingredients, purity, freshness and therapeutic benefit of the fish oils available today. The supplement industry is rife with false claims and unsavory companies that are far more interested in profiting on the fish oil craze than they are in your health and well-being.

Recommending that people take up to 20g/d of fish oil without conveying the importance of choosing a high quality fish oil, and teaching them how to do that, is irresponsible and possibly dangerous. Taking 20g/d of a poor quality, oxidized fish oil could dramatically increase oxidative damage and inflammation – which is of course exactly the opposite of the desired effect.

In this article, I’ll focus more on dispelling common misconceptions about fish oil and helping you to choose the best product for your needs.

Factors to consider when buying fish oil

There are seven primary variables to be aware of when shopping for a fish oil:

1. Purity. The oil must meet international standards for heavy metals, PCBs, dioxins and other contaminants. Many do not – even when they claim they do.
2. Freshness. Omega-3 oils are susceptible to oxidation, which makes them rancid. Rancid oils are pro-inflammatory and contribute to the diseases you’re trying to relieve or prevent by taking fish oil in the first place!
3. Potency. In order to have the desired anti-inflammatory effect, fish oil must contain an adequate amount of the long-chain omega-3 derivatives EPA and DHA. DHA is especially important.
4. Nutrients. All fish oils contain some amount of EPA and DHA. However, fish liver oil (from cod, skate or shark) also contains naturally occurring fat-soluble vitamins that are difficult to obtain from foods.
5. Bio-availability. The ability to absorb the beneficial components of fish oil is based on the molecular shape of the fatty acids. The more natural the structure the better.
6. Sustainability: The fish should be harvested in a sustainable manner and species that are under threat should be avoided.
7. Cost: the product must be relatively affordable to be practical for most people.

Purity

Many species of fish are known to concentrate toxic chemicals like heavy metals, PCBs, and dioxins which can cause serious disease, especially in children and developing fetuses. In a previous article I explained how these chemicals are typically not a concern when eating whole fish, because fish also contain selenium. Selenium binds to mercury and makes it unavailable to tissues, thus protecting against any damage it may cause.

And while fish constitute only 9% of our dietary intake of dioxins and PCBs, high doses of fish oils taken every day (as is often recommended) may raise this percentage significantly and expose us to undesirable levels of these toxins.

To address this, fish oil manufacturers use a process called molecular distillation to remove the toxins from the oil. When done correctly, molecular distillation is capable of reducing the toxins in fish oil to levels considered to be safe by the EPA and other agencies.

Although almost any fish oil manufacturer will tell you their product is free of these toxins, independent lab analyses tell a different story. Just last month (March, 2010), a lawsuit was filed in California court against the manufacturers of ten popular fish oils because they contained undisclosed and (possibly) unsafe levels of contaminants.

Unfortunately, this kind of deception is all too common in the supplement industry. That’s why it’s essential that you ask for something called a Certificate of Analysis (COA) from the manufacturer before you buy their product. A COA is an analysis performed by an independent lab to measure the ingredients of a product and confirm whether it lives up to the claims made by the manufacturer.

If the manufacturer won’t provide a COA, I start to get suspicious. This is standard practice in the industry and there’s no reason they shouldn’t be happy to show you theirs. Make sure that the independent lab they use is in fact independent and is preferably accredited, sponsored by a government agency, or has a solid reputation in the field.

This may seem like unnecessary paranoia, but when it comes to the possibility of ingesting powerful neurotoxins, it pays to do your homework.

In general, fish that are lower on the food chain like sardines and anchovies naturally have a lower concentration of contaminants. For this reason, it may be wise to look for a product made from these fish.

So what levels of these toxins are safe? As you might imagine, there is some disagreement on this question since there is no single governing body that determines acceptable levels. However, the standards that are most often followed by fish oil manufacturers are summarized in the table below.

* ppt = parts per trillion
* ppb = parts per billion

In a previous article we discussed selenium’s protective effect against mercury toxicity. If you are taking large doses of fish oil, and not eating any whole fish, it may be wise to ensure another regular source of selenium. Brazil nuts are by far the highest dietary source, with 1917mcg of selenium per 100g. (But they are also very high in n-6, so watch out!)

Freshness

I have written extensively about the dangers of oxidized, rancid oils. They promote oxidative damage and increase inflammation, both of which are risk factors for nearly every modern disease. The more unsaturated an fat is, the more vulnerable it is to oxidation. Long-chain, omega-3 fats found in fish oil are the most unsaturated of the fats, and thus the most susceptible to being damaged.

This is why it’s absolutely crucial to ensure that the fish oil you select is fresh and not rancid. Once it has gone rancid, it will have the exact opposite effect on your body than you want it to.

The first thing to do is to check something called the “peroxide value” on the COA. This is a measure of rancidity reactions in the oil that have occurred during storage. and should be less than 5 meq/kg.

If this checks out, and you decide to order that product, break open a capsule once you receive it. There should be no “fishy” odors. They should smell like the ocean, but not like a rotten fish. They should also not have a strong lemon or lime scent, which could be an indicator that the manufacturer is trying to mask the rancidity.

A common misconception is that you can determine the quality of a fish oil by freezing it. The theory goes that if you freeze the oil and it is cloudy, it’s rancid. That is not the case. All fish contain saturated and monounsaturated fatty acids, albeit in small amounts. These fatty acids make the capsules appear cloudy when frozen in products that contain whole fish oil (i.e. Vital Choice’s Wild Salmon Oil).

Potency

This is another area surrounded by significant controversy. Some argue the levels of individual constituents in fish oil aren’t paramount. Scientists discovered the healthful effects of omega-3s by studying people with fish-heavy diets, before supplemental fish oil even existed. Clinical trials using supplemental fish oils over the past few decades have contained widely variable levels of both long-chain omega-3 derivatives (EPA and DHA), and not super-high concentrations of either or both.

However, due to poor conversion of ALA to EPA and DHA, unless you are eating fish it is very likely you are deficient in long-chain omega-3s.

Following this line of reasoning, the DHA content in particular of fish and fish oils does seem important if we wish to obtain the best possible therapeutic effect. Many recent studies demonstrating the anti-inflammatory potential of fish oil used a daily dosage of DHA in the range of 1-3 grams. What’s more, foods like salmon roe that have been prized by traditional cultures for their nourishing and healing effects contain large amounts of DHA. A single 6 oz. serving of salmon roe contains 1 g of DHA. (In fact, this would be the best way by far of supplementing with DHA if money were no object. (Unfortunately, wild salmon roe goes for about $28/serving.)

The suggested DHA dose will of course depend upon the condition being treated. If you have a chronic inflammatory condition (heart disease, arthritis, Crohn’s or ulcerative colitis, etc.) I would suggest taking between 1 and 2 grams per day. If you are taking it simply for health maintenance, 500 mg is probably sufficient.

Unfortunately, many fish oils do not have significant amounts of DHA. This means you’d have to take an impractically high number of capsules each day to obtain the therapeutic dose. This is not desirable, since all unsaturated oils (including fish oils) are subject to oxidative damage. We don’t want to take large quantities of them for this reason.

Remember to check the label and ensure that your product has approximately 200-300 mg of DHA per capsule. This will allow you to achieve the therapeutic dose by taking no more than 3 capsules twice a day.

Nutrients

All fish oils contain some amount of EPA and DHA, the long-chain omega-3 derivatives that provide the majority of the anti-inflammatory benefits seen in studies. However, fish liver oils (from cod, skate or shark) contain significant amounts of vitamins A and D in addition to EPA and DHA. Vitamins A and D are fat-soluble nutrients that are crucial to human health. Vitamin D, in particular, is difficult to obtain from commonly eaten foods – especially now that eating seafood carries a much higher risk of contamination with toxins.

Fermented cod liver oil is even more beneficial, because it contains vitamin K2. Vitamin K2 has been called “the missing nutrient” because it was only recently discovered, and many people are deficient in it.

It has been commonly believed that the benefits of vitamin K are limited to its role in blood clotting. Another popular misconception is that vitamins K1 and K2 are simply different forms of the same vitamin – with the same physiological functions.

New evidence, however, has confirmed that vitamin K2’s role in the body extends far beyond blood clotting to include protecting us from heart disease, ensuring healthy skin, forming strong bones, promoting brain function, supporting growth and development and helping to prevent cancer – to name a few.

Cod liver oil was traditionally processed by fermentation, which is likely to make it more absorbable and bio-available. Processing by fermentation also avoids the use of heat, which can damage the fragile fatty acids and cause fish oils to go rancid. Unfortunately, I am aware of only one company that sells fermented cod liver oil at this time (see below).

Bio-availability

The ability to absorb the beneficial components of fish oil is based on the molecular shape of the fatty acids. In short, the more natural the structure and the less it is chemically altered, the better.

This is true for any nutrient, of course, and it explains why I am always in favor of obtaining nutrients from food or food-based sources when possible. Each additional step in processing from the natural state of a food to extract or isolate nutrients introduces the potential of damaging the nutrient, or changing it’s chemical form so that it’s more difficult to absorb or affects the body in a different way.

When it comes to fish oils, there are three forms currently available on the market:

1. Natural triglyercide oil. This is what you get when you “squeeze” the whole fish and extract the natural oil from it. It is the closest to eating fish oil in its natural form, and is highly bioavailable. The drawback of this form is that, because it’s not concentrated, it usually has low levels of EPA and DHA. And because it isn’t purified, it can have high levels of contaminants such as heavy metals, PCBs, and dioxins.
2. Ethyl ester oil. Occurs when natural triglyceride oil is concentrated and molecularly distilled to remove impurities. The ester form is still in a semi-natural state because it is the result of a process that naturally occurs in the body. The advantage to this form is that it can double or triple the levels of EPA and DHA.
3. Synthetic triglyceride oil. This form occurs when natural triglycerides are converted to ethyl esters for concentration (as above), but then re-converted into synthetic triglycerides. The original position of the triglyceride’s carbon bonds change and the molecule’s overall structure is altered, which impacts the bioavailability of the oil.

Studies on absorption of the various types of fish oil suggest that, unsurprisingly, the natural triglyceride form is absorbed better than the ethyl ester form, which in turn is absorbed better than the synthetic triglyceride form.

One study by Lawson & Hughes in 1988 showed that 1 gram of EPA and 0.67 grams of DHA as natural triglycerides were absorbed 3.4 and 2.7 fold as well as the ethyl ester triglycerides.

In the previous article we saw that fish oils were better absorbed when taken with a high-fat meal. In another study by Lawson & Hughes later the same year, they showed that the absorption of EPA & DHA from natural triglycerides improved from 69% with a low-fat meal (8g total fat) to 90% with a high-fat meal (44g total fat). Absorption of both EPA and DHA from ethyl ester oils was increased three-fold from 20% with a low-fat meal to 60% with a high fat meal.

What about krill oil?

In addition to the three types of fish oil listed above, there is another type of oil that provides EPA & DHA: krill oil. Krill oil (KO) is extracted from Anarctic krill, Euphausia superba, a zooplankton crustacean rich in phospholipids carrying EPA and DHA. Krill oil also contains various potent antioxidants, including vitamins A & E, astaxanthin, and a novel flavonoid whose properties are not yet fully understood.

Krill oil has a unique biomolecular profile that distinguishes it from other fish oils. While EPA and DHA in fish oils comes in the form of triglycerides, the EPA and DHA is already incorporated into phospholipids, which facilitates the passage of the fatty acids through the intestinal wall. This increases the bioavailability of the EPA and DHA and improves absorption and assimilation.

Werner et al demonstrated essential fatty acids in the form of phospholipids were superior to essential fatty acids as triglycerides in significantly increasing the phospholipid concentrations of EPA and DHA in mice.

In a human study, Bunea et al compared the effect of krill oil and fish oil on blood lipids, specifically total cholesterol, triglycerides, LDL, and HDL. Krill oil was given at dosages of 1g/d, 1.5g/d, 2g/d or 3g/d, and fish oil was given at a single dose of 3g/d. The authors found the following:

• KO at a daily dose of 1g, 1.5g, 2g or 3g achieved significant reductions of LDL of 32%, 36%, 37% and 39% respectively. Patients treated with 3g fish oil daily did not achieve a significant reduction in LDL.
• HDL was significantly increased in all patients receiving KO. HDL increased 44% at 1g/d, 43% at 1.5g/d, 55% at 2g/d and 59% at 3g/d. Fish oil taken at 3g/d increased HDL by only 4%.
• KO did not decrease triglycerides significantly at 1g and 1.5g. However, KO reduced triglycerides by 28% at 2g/d and 27% at 3g/d. Fish oil at 3g/d did not achieve a significant reduction of triglycerides.
• Blood glucose levels were reduced by 6.3% in patients receiving 1g/d and 1.5g/d of KO, and 5.6% in patients receiving 2g/d and 3g/d of KO. A daily dose of 3g of fish oil reduced blood glucose by 3.3%.

Thus, in this study krill oil led to a significantly greater improvement in blood lipids compared to fish oil.

Note that the dosage of KO that obtained the best results, either 2g/d or 3g/d, is quite high. However, study participants received a maintenance dose of 0.5g/d for another 12 weeks after the therapeutic period of the study ended. These patients maintained the reductions in total cholesterol they attained in the study, and LDL, triglycerides and blood glucose were further reduced from baseline. There was a moderate decrease (of 3%) in HDL, but HDL was still significantly increased from baseline.

There is also unpublished research suggesting that 300 mg/d of KO reduces biochemical and subjective measures of inflammation and improves joint function and mobility in patients with rheumatoid arthritis (RA).

However, as this research is not published or peer-reviewed, and was sponsored by Neptune Technologies (the manufacturer of Neptune Krill Oil (NKO), I am cautious about interpreting its results.

So what does all of this information about bio-availability tell us?

1. Taking fish oil capsules with a high-fat meal is essential to improve absorption of EPA and DH.
2. Even when taken with a high-fat meal, ethyl ester oils are absorbed only 66% as well as natural triglyceride oils.
3. Krill oil appears to significantly improve blood lipids when compared to fish oils, possibly because of its unique phospholipid structure.

Sustainability

The sustainability of fish oil production is difficult to gauge. Some oils are produced as a byproduct of fish harvesting, and manufacturers claim that they are simply making use of something that would normally be discarded. While this is certainly better than harvesting fish solely for their oil, it still supports harmful fishing practices.

The safest bet is to only use fish oil that is made from fish that are certified by MSF or a similar organization, such as the Environmental Defense Fund. Vital Choice Wild Salmon Oil is one example, as is Jarrow Max DHA (which is made from anchovies and sardines, both of which are generally regarded as safe to eat from an environmental standpoint).

Cost

I cover cost in the recommendations section below.

Recommendations

Which product you might choose from this list depends in large part upon what your goals are.

I have provided product recommendations in two different categories: baseline, and supplemental. Those wishing to to maintain health and ensure adequate nutrient intake should choose a product from the “baseline” category. Those who are dealing with a chronic inflammatory condition should also choose a product from the baseline category, but should consider adding a product from the “supplemental” category.

However, keep in mind that the absorption of the natural triglyceride oils (like the Wild Salmon Oil and Fermented Cod Liver Oil below) will be 1.5 times greater than the ethyl ester oils in the supplemental section. As a rule of thumb, all purified and molecularly distilled oils are ethyl esters.

This means you have to take 1.5 times as much of the ethyl ester oils to get the same dose of DHA that you’d get from the natural triglyceride oils. For example, Vital Choice Wild Salmon Oil has 220 mg DHA per serving. To get the same amount of DHA from Jarrow Max DHA, which is an ethyl ester oil, you’d have to take a serving that provides 333 mg of DHA.

Baseline

Green Pastures Fermented Cod Liver Oil and Butter Oil Blend (GP FCLO)

Ingredients: about 270 mg omega-3 (about 139 mg EPA, 83 mg DHA), about 1,100 IU vitamin D, about 2,300 IU vitamin A. Values listed are approximate (see disadvantages).

Price: $47.00 for 120 capsules, 2 capsules per serving. $0.78/serving.

Advantages: a whole-food product in its natural form, rather than a supplement. Is relatively low in EPA & DHA compared to other products, but contains high levels of vitamin D, as well as vitamins A & K. The fat soluble vitamins A, D & K2 are important co-factors and likely improve the absorption and assimilation of EPA & DHA. Addition of grass-fed butter oil increases levels of K2. Cold-processed with fermentation, which means this is the least oxidized product available.

Disadvantages: levels of PCBs are posted on Green Pastures’ website here, but I’ve been unable to obtain information on heavy metals or dioxins. The EPA and DHA levels are what would be expected in a whole food product, but may not be high enough for a significant anti-inflammatory effect. Values for vitamins A, D, EPA and DHA are approximate and vary batch to batch due to fermentation processing method. Peroxide values are not provided, but because it is processed without heat they are likely to be very low.

Notes: because fermented cod liver oil contains vitamins A, D and K2 in addition to EPA and DHA, and because most people are deficient in some or all of these nutrients, this is currently the only product I recommend to everyone – patients, family and friends – regardless of their health status.

Vital Choice Wild Salmon Oil (VC WSO)

Ingredients: 600 mg of omega-3 (240 mg EPA, 220 mg DHA), 340 IU vitamin D, 2,060 IU vitamin A (per 3 1,000 mg softgels).

Price: $40 bottle, 180 capsules. 3 capsules/serving, $0.68/serving.

Advantages: processed without heat using micro-filtration, which retains naturally occurring vitamins A and D. Fatty acids are in their natural triglyceride form, which makes them more absorbable. Also contains astaxanthin, which protects the oil from oxidative damage and rancidity. Contains more EPA and DHA than GP FCLO. Nutrient levels are more consistent from batch to batch and certification is performed by independent, not-for-profit organization (NSF International).

Disadvantages: when compared to GP FCLO, does not have vitamin K2 and the dose of vitamin D is significantly lower. Otherwise no disadvantages.

Supplemental

Jarrow Max DHA

Ingredients: 600 mg of omega-3 (250 mg DHA, 36 mg EPA) per capsule; one capsule is one serving.

Price: $14.85 (at Vitacost) for 180 capsules. $0.08/serving.

Advantages: even after considering the differences in absorptions between Jarrow Max (an ethyl ester) and the two natural triglyceride oils listed above, Jarrow Max is significantly cheaper. It’s possible to get 1g/d of DHA for $0.32. Made with anchovies and sardines, both of which are naturally low in contaminants. Jarrow faxed me their certificate of analysis, which checked out fine. This is a good choice for those wishing a high-dose of DHA in addition to eating fish or taking one of the natural triglyceride oils above.

Disadvantages: has a 7:1 ratio of DHA to EPA. Although I believe DHA to be more beneficial than EPA, the research is mixed on this and some people report that they do better with EPA.

V-Pure Vegetarian DHA

Ingredients: 350 mg DHA, 50 mg EPA per serving, 2 capsules per serving.

Price: $21.95 for 60 capsules. $0.73 per serving.

Advantages: I received several emails from vegetarians asking me what I recommended they do to meet DHA needs. This is a DHA/EPA blend derived from marine algae, which is where oily fish get EPA & DHA in the first place. The algae in this product is organically grown and 100% free of toxins and contaminants. The capsules are quite small and can be easily swallowed.

Disadvantages: I haven’t seen much research on the marine-algae DHA/EPA blends. Although it’s plausible to assume their effects would be similar to fish oils, I’d like to see some studies backing that up. Likewise, I don’t know much about V-Pure as a company. Another potential issue is that the capsules have carrageenan in them, which has been shown to exacerbate intestinal inflammation in several studies. People with gut problems like IBS and IBD may want to avoid this product. Finally, at $0.73/serving this product is expensive. To get a therapeutic dose of 1g/d taking this alone, you’d have to take 9 capsules per day which be 4.5 bottles/month, or almost $100!

Tentatively Recommended

Neptune Krill Oil

Ingredients: 300 mg of omega-3 (90 mg DHA, 150 mg EPA) per serving, two capsules per serving.

Price: $16.86 for 60 capsules. $0.56/serving, 2 capsules per serving.

Advantages: KO has a unique phospholipid structure that appears to improve the absorption of EPA & DHA. At least one study suggests that KO is superior to fish oil in improving blood lipids. KO also contains vitamins E & A, as well as astaxanthin, an antioxidant claimed to be 10 times more potent than other carotenoids. KO capsules are much smaller than fish oil capsules, are easier to swallow, and many report they don’t cause the burping common with other fish oil capsules. Several anecdotal reports suggest that krill oil can be more effective than fish oil in reducing inflammation for some people.

Disadvantages: there are few studies demonstrating the effectiveness of KO, whereas fish oil has decades of research behind it. Most of the studies that do exist on KO were sponsored by Neptune, the largest manufacturer of KO. The dosages used in the study on KO and blood lipids were very high, and taking KO at those dosages would be expensive. (However, the therapeutic dose of 2-3g/d would only be necessary for 12 weeks, as the maintenance dose of 0.5g seemed to maintain the benefits attained during the therapeutic period.) The sustainability of krill harvesting is controversial.

The reason KO gets a tentative recommendation is that there’s still comparatively little research supporting its use, and because I am still uncertain about the environmental impact of harvesting the krill for the oil. If you have information to share on either of these questions, I’m all ears!

So far in this series we’ve looked at why fish is superior to plant-based sources of omega-3. We’ve examined the importance of reducing consumption of omega-6 fats. We’ve considered how much omega-3 is needed to support health and treat disease. And we’ve revealed that concerns about the safety of fish consumption have been overblown, and that eating fish regularly is not only safe, but incredibly beneficial.

In this article we’re going to compare fish with fish oil as a means of meeting our omega-3 needs, and for overall health and wellness. The comparison will be based on the following criteria: nutrient content, potency, absorption, cost and environmental impact.

Fish oil has become wildly popular in the last few years, as people increasingly understand the importance of omega-3 in the diet. However, part of the reason for fish oil’s popularity is related to concerns about the safety of eating whole fish – concerns that we now know are unfounded.

With this in mind, let’s see whether whole fish or fish oil are the best choice for most people.

Nutrient content

Fish: contain not only EPA and DHA, but also vitamin D, selenium, protein, co-factors and a more complete fatty acid profile than fish oil. Selenium, in particular, is important because it protects against mercury toxicity. Vitamin D protects against nearly every modern disease plaguing us today. A 6 oz. portion of wild salmon contains 1,700 IU of D, which is difficult to obtain in that amount from other dietary sources.

Fish oil: most oils contain only EPA and DHA, although salmon and cod liver oil also contain moderate amounts of vitamin D. Fish oil has a more limited fatty acid profile than whole fish, and doesn’t contain selenium.

Potency (levels of EPA & DHA)

Fish: a 6 oz. portion of wild salmon contains 883 mg of EPA and 1,111 mg of DHA. 2-3 servings a week of salmon, combined with a low intake on omega-6, would be adequate for most people.

Fish oil: this is where fish oil may have an advantage over fish. Because it is molecularly distilled and purified, fish oil can have high concentrations of DHA and EPA. 6 capsules of Jarrow Max DHA would provide 1.5g/day of DHA, a level that would be difficult to obtain from eating fish. You’d have to eat approximately 8.5 ounces of wild salmon every day to obtain that much DHA.

Absorption

Here’s where things get a bit tricky. I talked about potency above, and mentioned the levels of EPA and DHA in both fish and fish oil. However, those levels mean very little unless we consider how well they’re absorbed.

Several studies indicate that fish oil supplementation is not as effective as epidemiological evidence on the benefits of fish consumption suggest it would be. It appears that the presence of other fats in the fish activates processes required to absorb the EPA and DHA properly. This explains why the EPA and DHA are better absorbed from eating whole fish than from taking fish oil.

In one study comparing the effects of fish and fish oil, researchers found that levels of DHA after 6 weeks of salmon consumption were nine times higher than after fish oil administration.

The authors hypothesized that the configuration of fatty acids in whole fish is familiar to our body and thus easier to absorb. Conversely, the fish oil alone doesn’t adequately activate the process of fat absorption required to assimilate the fatty acids.

Another study confirmed this by demonstrating that fish oil is absorbed much better in the presence of a high-fat meal. They found that the content of n-3 fatty acids in the body tissues rose dramatically when the fish oil was taken along with 12g of olive oil.

We can draw two conclusions from these studies:

1. EPA, and especially DHA, is much better absorbed from fish than fish oil. The effect may be as great as nine-fold. This means that we would need nine times less DHA from fish to obtain the same amount of DHA from fish oil. Put another way, we’d need nine times more DHA from fish oil to obtain the same amount of DHA from fish. So, using the 6 oz. portion of salmon as an example, with 1.1g of DHA, we would need to take 9.9g of DHA from fish oil – roughly 36 capsules/day of the Jarrow Max DHA – to obtain the same amount of DHA we’d get from the salmon. That’s a lot of fish oil!
2. On the other hand, taking fish oil capsules with a high-fat meal can greatly improve their absorption, to the point where they may be on par with whole fish. (I say “may be” because the scientific literature is mixed on this.) This is likely due to the effect described above, where the presence of other fats activates the body’s fat absorption mechanisms.

Cost

This is also tricky to compare, since prices and availability of fish vary regionally. A straight comparison of the cost of DHA obtained from fish and fish oil also ignores other important factors, which we’ve already discussed above, such as the presence of other nutrients and the differences in absorption.

Let’s assume for the sake of comparison that fish oil is taken with a high-fat meal to improve absorption and that absorption rates of EPA and DHA are roughly similar between the two. Let’s assume that wild salmon is available for $13/lb. (I know it is much less in some areas, and much more in others).

Let’s assume also that we’re shooting for a daily intake of 500 mg of DHA.

To obtain this amount of DHA from salmon, you’d have to eat just over one pound per week (19 ounces). That would cost you $15.45.

To obtain this amount of DHA from Jarrow Max DHA, you’d have to take 2 capsules per day. Assuming you bought a bottle of 180 capsules from Vitacost for $14.70, you’d pay just $1.14 for the same amount of DHA.

However, you’d have to consider the following caveats:

1. It’s uncertain whether, even with a high fat meal, you’d be absorbing the same amount of DHA from the fish oil as you would from the salmon
2. The salmon has large amounts of protein, selenium, vitamin D and other fatty-acids and co-factors that the Jarrow fish oil doesn’t have
3. Other oily fish that are significantly cheaper than salmon, such as sardines and mackerel, are also very high in EPA and DHA.

Environmental impact

Overfishing and fish farming have already seriously damaged the health of marine ecosystems, and threaten to do even more damage if fish and fish oil consumption increases.

Much has been written about this elsewhere. Charles Clover’s The End of the Line: How Overfishing is Changing the World and What We Eat provides a particularly astute (and scary) analysis of the impacts of current methods of fishing on global ecosystems.

In short, I believe the most responsible choice we can make is to limit the fish we eat to those certified by groups like the Marine Stewardship Council (MSC).

However, even those groups are not infallible. Recently concerns have been raised over MSC’s decision to certify a salmon fishery in British Columbia where the salmon population is declining rapidly. Environmentalists and scientists have protested the decision, but the MSC seems to have moved ahead regardless.

Unfortunately it’s not a cut and dry issue, and those who are interested in eating fish harvested in a sustainable matter will have to do their own research and stay abreast of changing policies and practices.

In general, though, most environmentalists and scientists support the MSC certification. MSC has a list of fish they consider safe to eat on their website, which you can refer to.

MSC also has a certification label (pictured below) they provide to vendors of MSC-certified fish that you can look for when you’re shopping.

The sustainability of fish oil production is even more difficult to gauge. Some oils are produced as a byproduct of fish harvesting, and manufacturers claim that they are simply making use of something that would normally be discarded. While this is certainly better than harvesting fish solely for their oil, it still supports harmful fishing practices.

The safest bet is to only use fish oil that is made from fish that are certified by MSF or a similar organization, such as the Environmental Defense Fund. Vital Choice Wild Salmon Oil is one example, as is Jarrow Max DHA (which is made from anchovies and sardines, both of which are generally regarded as safe to eat from an environmental standpoint).

The verdict

The question of whether fish or fish oil is a better choice is complex and depends upon several different factors. These include whether DHA is needed for maintenance or therapeutic effect, access to sustainability caught wild fish, financial considerations, and the presence of other nutrients in fish.

For those who are generally healthy and want to stay that way, I think reducing omega-6 consumption and eating a moderate amount of oily fish (2-3 6 oz. portions per week) is the best choice. This will get you plenty of EPA & DHA along with high quality protein, selenium and vitamin D. If wild salmon is out of your price range, mackerel and sardines are both high in EPA and DHA and certified by the MSC as safe to eat.

For those who have a chronic, inflammatory condition such as cardiovascular disease or an autoimmune disorder, I would recommend a combination of whole fish (perhaps the same 2-3 6 oz. portions per week) along with a high quality fish oil. This ensures that you are getting the benefits of whole fish along with the added therapeutic effect of higher doses of DHA and EPA. Somewhere around 1.5g per day of DHA would be a good therapeutic dose, which would mean taking 1g/day of DHA in fish oil capsules in addition to the three 6 oz. portions of oily fish.

In the next and final article of this series, I’ll discuss the criteria for choosing a fish oil and make recommendations based on those criteria and clinical experience.

In the first article of this series, we discussed the problems humans have converting omega-3 (n-3) fats from plant sources, such as flax seeds and walnuts, to the longer chain derivatives EPA and DHA. In the second article, we discussed how excess omega-6 (n-6) in the diet can block absorption of omega-3, and showed that the modern, Western diet contains between 10 and 25 times the optimal level of n-6.

In this article we’ll discuss strategies for bringing the n-6 to n-3 ratio back into balance. There are two obvious ways to to do this: increase intake of n-3, and decrease intake of n-6.

Many recommendations have been made for increasing n-3 intake. The important thing to remember is that any recommendation for n-3 intake that does not take the background n-6 intake into account is completely inadequate.

It’s likely that the success and failure of different clinical trials using similar doses of EPA and DHA were influenced by differing background intakes of the n-6 fatty acids. In the case of the Lyon Diet Heart Study, for example, positive outcomes attributed to ALA may be related in part to a lower n-6 intake (which would enhance conversion of ALA to EPA and DHA).

This explains why simply increasing intake of n-3 without simultaneously decreasing intake of n-6 is not enough.

Bringing n-3 and n-6 back into balance: easier said than done!

Let’s examine what would happen if we followed the proposed recommendation of increasing EPA & DHA intake from 0.1 to 0.65g/d. This represents going from eating virtually no fish to eating a 4-oz. serving of oily fish like salmon or mackerel three times a week.

The average intake of fatty acids (not including EPA & DHA) in the U.S. has been estimated as follows:

• N-6 linoleic acid (LA): 8.91%
• N-6 arachidonic acid (AA): 0.08%
• N-3 alpha-linolenic acid (ALA): 1.06%

Keep in mind from the last article that the optimal ratio of omega-6 to omega-3 is estimated to be between 1:1 and 2.3:1. Assuming a median intake of n-6 (ALA + LA) at 8.99% of total calories in a 2,000 calorie diet, that would mean a daily intake of 19.9g of n-6. If we also assume the recommended intake of 0.65g/d of EPA and DHA, plus an average of 2.35g/d of ALA (1.06% of calories), that’s a total of 3g/d of n-3 fatty acid intake.

This yields an n-6:n-3 ratio of 6.6:1, which although improved, is still more than six times higher than the historical ratio (i.e. 1:1), and three times higher than the ratio recently recommended as optimal (i.e. 2.3:1).

On the other hand, if we increased our intake of EPA and DHA to the recommended 0.65g/d (0.3% of total calories) and maintained ALA intake at 2.35g/d, but reduced our intake of LA to roughly 7g/d (3.2% of total calories), the ratio would be 2.3:1 – identical to the optimal ratio.

Further reducing intake of n-6 to less than 2% of calories would in turn further reduce the requirement for n-3. But limiting n-6 to less than 2% of calories is difficult to do even when vegetable oils are eliminated entirely. Poultry, pork, nuts, avocados and eggs are all significant sources of n-6. I’ve listed the n-6 content per 100g of these foods below:

• Walnuts: 38.1g
• Chicken, with skin: 2.9g
• Avocado: 1.7g
• Pork, with fat: 1.3g
• Eggs: 1.3g

It’s not too hard to imagine a day where you eat 200g of chicken (5.8g n-6), half an avocado (1.1g n-6) and a handful of walnuts (10g of n-6). Without a drop of industrial seed oils (like safflower, sunflower, cottonseed, soybean, corn, etc.) you’ve consumed 16.9g of n-6, which is 7.6% of calories and far above the limit needed to maintain an optimal n:6 to n:3 ratio.

Check the chart below for a listing of the n-6 and n-3 content of several common foods.

Click the thumbnail for a larger version

Ditch the processed foods and cut back on eating out

Of course, if you’re eating any industrial seed oils you’ll be way, way over the optimal ratio in no time at all. Check out these n-6 numbers (again, per 100g):

• Sunflower oil: 65.7g
• Cottonseed oil: 51.5g
• Soybean oil: 51g
• Sesame oil: 41.3g
• Canola oil: 20.3g

Holy moly! The good news is that few people these days still cook with corn, cottonseed or soybean oil at home. The bad news is that nearly all processed and packaged foods contain these oils. And you can bet that most restaurant foods are cooked in them as well, because they’re so cheap.

So chances are, if you’re eating foods that come out of a package or box on a regular basis, and you eat out at restaurants a few times a week, you are most likely significantly exceeding the recommended intake of n-6.

Two other methods of determining healthy n-3 intakes

Tissue concentration of EPA & DHA

Hibbeln et al have proposed another method of determining healthy intakes of n-6 and n-3. Studies show that the risk of coronary heart disease (CHD) is 87% lower in Japan than it is in the U.S, despite much higher rates of smoking and high blood pressure.

When researchers examined the concentration of n-3 fatty acids in the tissues of Japanese subjects, they found n-3 tissue compositions of approximately 60%. Further modeling of available data suggests that a 60% tissue concentration of n-3 fatty acid would protect 98.6% of the worldwide risk of cardiovascular mortality potentially attributable to n-3 deficiency.

Of course, as I’ve described above, the amount of n-3 needed to attain 60% tissue concentration is dependent upon the amount of n-6 in the diet. In the Phillipines, where n-6 intake is less than 1% of total calories, only 278mg/d of EPA & DHA (0.125% of calories) is needed to achieve 60% tissue concentration.

In the U.S., where n-6 intake is 9% of calories, a whopping 3.67g/d of EPA & DHA would be needed to achieve 60% tissue concentration. To put that in perspective, you’d have to eat 11 ounces of salmon or take 1 tablespoon (yuk!) of a high-potency fish oil every day to get that much EPA & DHA.

This amount could be reduced 10 times if intake of n-6 were limited to 2% of calories. At n-6 intake of 4% of calories, roughly 2g/d of EPA and DHA would be needed to achieve 60% tissue concentration.

The Omega-3 Index

Finally, Harris and von Schacky have proposed a method of determining healthy intakes called the omega-3 index. The omega-3 index measures red blood cell EPA and DHA as a percentage of total red blood cell fatty acids.

Values of >8% are associated with greater decreases in cardiovascular disease risk. (Note that n-6 intake was not considered in Harris and von Shacky’s analysis.) However, 60% tissue concentration of EPA & DHA in tissue is associated with an omega-3 index of between 12-15% in Japan, so that is the number we should likely be shooting for to achieve the greatest reduction in CVD mortality.

The omega-3 index is a relatively new test and is not commonly ordered by doctors. But if you want to get this test, you can order a finger stick testing kit from Dr. William Davis’ Track Your Plaque website here. It’ll cost you $150 bucks, though.

What does it all mean to you?

These targets for reducing n-6 and increasing n-3 may seem excessive to you, given current dietary intakes in the U.S.. Consider, however, that these targets may not be high enough. Morbidity and mortality rates for nearly all diseases are even lower for Iceland and Greenland, populations with greater intakes of EPA & DHA than in Japan.

All three methods of calculating healthy n-3 and n-6 intakes (targeting an n-6:n-3 ratio of 2.3:1, 60% EPA & DHA tissue concentration, or 12-15% omega-3 index) lead to the same conclusion: for most people, reducing n-6 intake and increasing EPA & DHA intake is necessary to achieved the desired result.

To summarize, for someone who eats approximately 2,000 calories a day, the proper n-6 to n-3 ratio could be achieved by:

1. Making no changes to n-6 intake and increasing intake of EPA & DHA to 3.67g/d (11-oz. of oily fish every day!)
2. Reducing n-6 intake to approximately 3% of calories, and following the current recommendation of consuming 0.65g/d (three 4-oz. portions of oily fish per week) of EPA & DHA.
3. Limiting n-6 intake to less than 2% of calories, and consuming approximately 0.35g/d of EPA & DHA (two 4-oz. portions of oily fish per week).

Although option #1 yields 60% tissue concentration of EPA & DHA, I don’t recommend it as a strategy. All polyunsaturated fat, whether n-6 or n-3, is susceptible to oxidative damage. Oxidative damage is a risk factor for several modern diseases, including heart disease. Increasing n-3 intake while making no reduction in n-6 intake raises the total amount of polyunsaturated fat in the diet, thus increasing the risk of oxidative damage.

This is why the best approach is to limit n-6 intake as much as possible, ideally to less than 2% of calories, and moderately increase n-3 intake. 0.35g/d of DHA and EPA can easily be obtained by eating a 4 oz. portion of salmon twice a week.

In the last article we discussed the problems humans have converting omega-3 (n-3) fats from plant sources, such as flax seeds and walnuts, to the longer chain derivatives EPA and DHA. Since EPA and DHA (especially DHA) are responsible for the benefits omega-3 fats provide, and since EPA and DHA are only available in significant amounts in seafood, it follows that we should be consuming seafood on a regular basis.

But how much is enough? What does the research literature tell us about the levels of EPA and DHA needed to prevent disease and ensure proper physiological function?

I’m going to answer this question in detail in the next article. But before I do that, I need to make a crucial point: the question of how much omega-3 to eat depends in large part on how much omega-6 we eat.

Over the course of human evolution there has been a dramatic change in the ratio of omega-6 and omega-3 fats consumed in the diet. This change, perhaps more than any other dietary factor, has contributed to the epidemic of modern disease.

The historical ratio of omega-6 to omega-3

Throughout 4-5 million years of hominid evolution, diets were abundant in seafood and other sources of omega-3 long chain fatty acids (EPA & DHA), but relatively low in omega-6 seed oils.

Anthropological research suggests that our hunter-gatherer ancestors consumed omega-6 and omega-3 fats in a ratio of roughly 1:1. It also indicates that both ancient and modern hunter-gatherers were free of the modern inflammatory diseases, like heart disease, cancer, and diabetes, that are the primary causes of death and morbidity today.

At the onset of the industrial revolution (about 140 years ago), there was a marked shift in the ratio of n-6 to n-3 fatty acids in the diet. Consumption of n-6 fats increased at the expense of n-3 fats. This change was due to both the advent of the modern vegetable oil industry and the increased use of cereal grains as feed for domestic livestock (which in turn altered the fatty acid profile of meat that humans consumed).

The following chart lists the omega-6 and omega-3 content of various vegetable oils and foods:

Vegetable oil consumption rose dramatically between the beginning and end of the 20th century, and this had an entirely predictable effect on the ratio of omega-6 to omega-3 fats in the American diet. Between 1935 and 1939, the ratio of n-6 to n-3 fatty acids was reported to be 8.4:1. From 1935 to 1985, this ratio increased to 10.3:1 (a 23% increase). Other calculations put the ratio as high as 12.4:1 in 1985. Today, estimates of the ratio range from an average of 10:1 to 20:1, with a ratio as high as 25:1 in some individuals.

In fact, Americans now get almost 20% of their calories from a single food source – soybean oil – with almost 9% of all calories from the omega-6 fat linoleic acid (LA) alone! (PDF)

This reveals that our average intake of n-6 fatty acids is between 10 and 25 times higher than evolutionary norms. The consequences of this dramatic shift cannot be overestimated.

Omega-6 competes with omega-3, and vice versa

As you may recall from the last article, n-6 and n-3 fatty acids compete for the same conversion enzymes. This means that the quantity of n-6 in the diet directly affects the conversion of n-3 ALA, found in plant foods, to long-chain n-3 EPA and DHA, which protect us from disease.

Several studies have shown that the biological availability and activity of n-6 fatty acids are inversely related to the concentration of of n-3 fatty acids in tissue. Studies have also shown that greater composition of EPA & DHA in membranes reduces the availability of AA for eicosanoid production. This is illustrated on the following graph, from a 1992 paper by Dr. William Landis:

The graph shows the predicted concentration of n-6 in the tissue based on dietary intake of n-3. In the U.S. the average person’s tissue concentration of highly unsaturated n-6 fat is 75%. Since we get close to 10% of our calories from n-6, our tissue contains about as much n-6 as it possibly could. This creates a very inflammatory environment and goes a long way towards explaining why 4 in 10 people who die in the U.S. each year die of heart disease. (Note: the ratio of omega-6 to omega-3 matters, but so does the total amount of each.)

In plain english, what this means is that the more omega-3 fat you eat, the less omega-6 will be available to the tissues to produce inflammation. Omega-6 is pro-inflammatory, while omega-3 is neutral. A diet with a lot of omega-6 and not much omega-3 will increase inflammation. A diet of a lot of omega-3 and not much omega-6 will reduce inflammation.

Big Pharma is well aware of the effect of n-6 on inflammation. In fact, the way over-the-counter and prescription NSAIDs (ibuprofen, aspirin, Celebres, etc.) work is by reducing the formation of inflammatory compounds derived from n-6 fatty acids. (The same effect could be achieved by simply limiting dietary intake of n-6, as we will discuss below, but of course the drug companies don’t want you to know that. Less profit for them.)

As we discussed in the previous article, conversion of the short-chain n-3 alpha-linolenic acid (ALA), found in plant foods like flax and walnut, to DHA is extremely poor in most people. Part of the reason for that is that diets high in n-6 LA inhibit conversion of ALA to DHA. For example, one study demonstrated that an increase of LA consumption from 15g/d to 30g/d decreases ALA to DHA conversion by 40%.

Death by vegetable oil

So what are the consequences to human health of an n-6:n-3 ratio that is up to 25 times higher than it should be?

The short answer is that elevated n-6 intakes are associated with an increase in all inflammatory diseases – which is to say virtually all diseases. The list includes (but isn’t limited to):

• cardiovascular disease
• type 2 diabetes
• obesity
• metabolic syndrome
• irritable bowel syndrome & inflammatory bowel disease
• macular degeneration
• rheumatoid arthritis
• asthma
• cancer
• psychiatric disorders
• autoimmune diseases

The relationship between intake n-6 fats and cardiovascular mortality is particularly striking. The following chart, from an article entitled Eicosanoids and Ischemic Heart Disease by Stephan Guyenet, clearly illustrates the correlation between a rising intake of n-6 and increased mortality from heart disease:

As you can see, the USA is right up there at the top with the highest intake of n-6 fat and the greatest risk of death from heart disease.

On the other hand, several clinical studies have shown that decreasing the n-6:n-3 ratio protects against chronic, degenerative diseases. One study showed that replacing corn oil with olive oil and canola oil to reach an n-6:n-3 ratio of 4:1 led to a 70% decrease in total mortality. That is no small difference.

Joseph Hibbeln, a researcher at the National Institute of Health (NIH) who has published several papers on n-3 and n-6 intakes, didn’t mince words when he commented on the rising intake of n-6 in a recent paper:

The increases in world LA consumption over the past century may be considered a very large uncontrolled experiment that may have contributed to increased societal burdens of aggression, depression and cardiovascular mortality.

And those are just the conditions we have the strongest evidence for. It’s likely that the increase in n-6 consumption has played an equally significant role in the rise of nearly every inflammatory disease. Since it is now known that inflammation is involved in nearly all diseases, including obesity and metabolic syndrome, it’s hard to overstate the negative effects of too much omega-6 fat.

In the next article we’ll discuss three different methods for determining healthy intakes of n-3 that take background intake of n-6 into account.

I want to thank everyone for sending in their questions and voting on the next topic. The good news is that there’s a lot of interest in all of the topics I’m researching right now. The bad news is that there was no clear winner.

Finally, stay tuned for the first episode of The Healthy Skeptic audio podcast, coming up next week. I’ll be interviewing Stephan Guyenet, Ph.D, on the subject of obesity and weight regulation. Stephan is a senior fellow at the University of Washington studying the neurobiology of body fat regulation. He’s also the author of Whole Health Source, which is one of my favorite health related blogs.

Before we get into talking about the benefits of fish consumption, or how how much fish or fish oil you should eat, it’s probably a good idea to start with a basic review of the omega-3 fatty acids.

Essential Fatty Acids 101

A fatty acid is a chain of carbon, oxygen and hydrogen atoms with a carboxyl group on one end. Fatty acids are classified on the basis of how many carbon atoms are in the chain, as well as how many double bonds exist within the molecule.

Fish contain a variety of fatty acids, but the ones that are believed to confer the majority of the benefits are the long-chain omega-3 fats eicosapentanaenoic acid (EPA) and docosahexaenoic acid (DHA). These omega-3 fats are found exclusively in seafood and marine algae.

As you can see from the chart below, it is also possible for the body to synthesize EPA and DHA from the short-chain omega-3 alpha-linolenic acid (ALA). ALA is found in plant foods such as flax, hemp and pumpkin seeds and walnuts.

Click thumbnail for a larger version

However, research clearly indicates that the conversion of ALA to EPA and DHA is extremely limited. Less than 5% of ALA gets converted to EPA, and less than 0.5% (one-half of one percent) of ALA is converted to DHA.

A common misconception, especially amongst vegetarians and vegans, is that our need for EPA and DHA can be met by consuming flax oil and other plant sources of ALA. But the conversion numbers above clearly indicate that this isn’t the case.

Studies have shown that ALA supplements (like flax oil) are unable to raise plasma DHA levels in vegans, despite low DHA levels at baseline. (ref) So unless they are supplementing with an algae-derived source of DHA, it is likely that most vegetarians and vegans are deficient.

This is significant because researchers now believe that the majority of the health benefits we get from dietary omega-3 fats come from the longer chain derivatives (especially DHA, as I will explain below).

Is DHA essential?

In fact, some researchers have proposed that DHA is essential. When scientists label a nutrient as “essential”, they they’re not just saying that it’s “very important”. In the context of nutrition essential means that the nutrient cannot be synthesized in the human body, and must be derived from dietary sources.

According to today’s nutrition textbooks, there are only two essential fatty acids, omega-6 linoleic acid (LA) and omega-3 alpha-linolenic acid (ALA). It is believed that as long as these fats are present in the diet, all of the longer-chain omega-3 and omega-6 derivatives can be synthesized in the body.

As I pointed out above, while this is theoretically possible, in reality the conversion doesn’t work well. This is true even for healthy people, but it’s especially true for those with nutrient deficiencies, because the conversion of ALA to DHA depends on zinc, iron and pyridoxine.

The bioavailability of iron in plant sources is poor compared to animal sources, so iron deficiency is common in vegans and vegetarians. This is another reason why they tend to be poor converters of ALA to DHA.

Several other observations support the hypothesis that DHA is essential:

• DHA content in the tissues of all mammals is very similar despite widely varying intakes of omega-3 fatty acids. ¹
• DHA and AA, but not other omega-3 or omega-6 fatty acids, are selectively transferred across the placenta (PDF).
• 60% of the dry matter of the brain is lipid, and DHA and AA are the most abundant fatty acids of brain phospholipids (PDF)
• DHA status in newborns is much lower in those receiving formula with LA and ALA, than in those receiving milk or formula with pre-formed DHA (PDF)

It is possible that the primarily carnivorous diet of our ancestors, which ensured a consistently high dietary intake of DHA and AA, precluded the need to evolve efficient conversion mechanisms.

In other words, since we were eating a lot of meat and fish with pre-formed DHA and AA, our bodies didn’t need to be experts at converting ALA and LA in plants to DHA and AA. It is far easier for the body to assimilate pre-formed DHA and AA than it is to synthesize them from precursors.

What about EPA? Isn’t it essential too?

EPA is another long-chain omega-3 fatty acid that is conventionally believed to be responsible for the benefits of fish consumption.

EPA is often referred to as “anti-inflammatory”. However, according to this report on essential fatty acids by Masterjohn, EPA’s effect seems to be more of an interference with the metabolism of omega-6 arachidonic acid (AA) than the performance of any essential role itself.

Take a look at the chart again that I linked to in the beginning of the post. The fatty acids in blue boxes are less inflammatory, and those in pink boxes are more inflammatory. The chart shows that AA is used to synthesize prostaglandins that cause inflammation (indicated by the pink box on the chart). Because it has the same number of carbon atoms, EPA competes with AA for the enzymes that metabolize it. Since the prostaglandins made by EPA are less inflammatory than those made by AA (indicated by the blue box), EPA is often referred to as “anti-inflammatory”.

But while EPA is certainly less inflammatory than AA, it doesn’t make sense that the body would require an essential fatty acid just to block the inflammatory effects of of another fatty acid.

By contrast, DHA is used to synthesize compounds that play an active role in resolving inflammation. EPA only makes these compounds in the presence of aspirin (PDF). EPA is thus likely to simply be a byproduct of compromised DHA synthesis.

What does this mean to you?

Putting all of this information together yields the following conclusions:

1. DHA is the most important of the omega-3 fatty acids, and is primarily responsible for the benefits we get from consuming them.
2. DHA is likely to be essential, which means that you must consume it in the diet to prevent disease and ensure optimal function.
3. The conversion of plant sources of ALA, such as flax seed oil, to DHA is poor in healthy people and even worse in people deficient in certain nutrients. Vegans and vegetarians are especially prone to be poor converters of ALA to DHA.
4. If you’ve been buying flax oil in the hopes that it will help, you’d be far better off putting that money towards some fish or fish oil capsules.

Dietary changes over the past century have lowered the DHA status to a state of subclinical deficiency in many people. Countless studies show that this deficiency is at least in part to blame for the rising incidence of cardiovascular disease, inflammatory disease, mental and psychiatric disorders and suboptimal neurodevelopment.

DHA is not the only reason to eat fish, which is also rich in selenium and vitamin D. However, DHA is likely to be the primary reason why populations that eat fish on a regular basis have consistently been shown to healthier than those that don’t. We’ll discuss this further in the next article.