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Ask Chris: Is Fructose Really That Bad?


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Paul from Facebook asks:

What are your thoughts on fructose? Is it really as bad as Paleo is making it out to be?

Dr. Robert Lustig has worked hard in recent years to demonize fructose, and his efforts have paid off. His YouTube video “Sugar: The Bitter Truth” has over 2.5 million views as of this writing. Lustig et al. claim that fructose is a uniquely fattening poison (when compared to glucose) that is as toxic to the liver as alcohol.

But is this true? Does the current evidence support this position? I’ve changed my views on this over time as I’ve become better acquainted with the literature, so I’d like to share my current understanding with you.

When it comes to fructose, calories matter

There’s no doubt that refined sugar – including fructose – can be problematic. But studies suggest that this is only true when calories are in excess.

This may be the most dangerous aspect of refined sugar: it leads to unintentional overeating. In a recent post on fructose, obesity researcher Stephan Guyenet points out that most people in these studies aren’t deliberately overfeeding. They are inadvertently overfeeding because they aren’t spontaneously compensating for the calories added to the diet via a large fructose- or glucose-sweetened beverage.

This doesn’t happen with fruit or other whole foods that contain glucose or fructose.

When people add fruit to their diet, they reduce their calorie intake elsewhere to compensate. Not so with liquid-sweetened beverages like soft drinks.

When people add a soda or two a day to their diet, they tend not to reduce consumption of other foods, and thus their calorie intake increases.

This is where fructose does appear to be more harmful than glucose. Although people don’t compensate for calories added via glucose or fructose, the fructose-sweetened beverages have more serious metabolic effects.

Is fructose uniquely fattening?

Dr. Lustig argues that, when compared to glucose, fructose is uniquely fattening. He claims that fructose is the most efficient substrate for de novo lipogenesis (DNL), which is the process by which the liver converts carbohydrates to fat.

However, Dr. Lustig relies on animal evidence that doesn’t apply to humans. There’s a big difference between mouse carbohydrate metabolism and human carbohydrate metabolism. When mice are on a high-carbohydrate diet that doesn’t provide excess calories, it’s common to see DNL rates of 50 percent and up. In other words, they are efficient at converting carbohydrates into fat, even when they’re not overeating. (1)

But in humans on an isocaloric diet (without excess calories), de novo lipogenesis falls into the range of 10 to 20 percent. The conversion of carbohydrate is less efficient in humans than it is in mice.

The research in this area is robust and uncontroversial. Nearly 50 controlled feeding studies have been performed on various aspects of cardiometabolic control. Most investigators working in this field believe that DNL in humans is negligible in response to fructose, and doesn’t comprise a significant source of dietary calories.

There’s another problem with extrapolating the animal evidence to humans in this case. The mice in the studies Lustig cites are eating huge amounts of fructose: up to 60 percent of total calories. You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.

According to researcher Dr. Sievenpiper in an interview with science writer David Despain at Evolving Health, the 50th percentile intake for people in the U.S. is 49 grams per day, which works out to 10 percent of total calories. Even the 95th percentile intake of 87 grams per day doesn’t exceed 20 percent of calories. That’s a lot of fructose, but it’s nowhere near the 60 percent of calories fed to mice.

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Is fructose an evil toxin?

Dr. Lustig refers to fructose is a “poison” that is nearly as toxic to the liver as alcohol. But again, human evidence doesn’t support this claim.

In a recent paper, Dr. Luc Tappy and colleagues labeled acetate, fructose and different metabolites with stable isotope tracers so they could see how fructose is metabolized in the human body. (2) They found that 50 percent ends up as glucose, 25 percent goes to lactate and greater than 15 percent goes to glycogen. The remainder is oxidized directly (to CO2 through the TCA cycle) and a small portion – as low as 2-3% – is converted to fat via de novo lipogenesis.

Glucose and glycogen are easily processed by the body, and 2-3% conversion to fat is not significant. And while some have claimed that lactate may be problematic, a paper published more than a decade ago contradicts this. (Hat tip to Evelyn from CarbSane.) According to the authors:

The bulk of the evidence suggests that lactate is an important intermediary in numerous metabolic processes, a particularly mobile fuel for aerobic metabolism, and perhaps a mediator of redox state among various compartments both within and between cells… Lactate can no longer be considered the usual suspect for metabolic ‘crimes’, but is instead a central player in cellular, regional and whole body metabolism.

Translation: lactate from fructose isn’t a problem.

What does this mean for you and fructose?

Fructose-sweetened beverages like soft drinks and juice cause metabolic problems when calories are in excess, and studies have shown that people are not likely to compensate for the additional calories they get from such beverages.

This is why soft drinks and other beverages sweetened with fructose aren’t a good idea. That said, an occasional glass of fruit juice within the context of an isocaloric diet is unlikely to cause problems – unless you have a pre-existing blood sugar issue.

I don’t think there’s any basis for avoiding whole fruit simply because it contains fructose. As I’ve shown in this article, there’s nothing uniquely fattening or toxic about fructose when it isn’t consumed in excess. And since whole fruit contains fiber and other nutrients, it’s difficult to eat a lot of fruit without simultaneously reducing intake of other foods.

Fruit has been part of the human diet for longer than we’ve been, er, human. We’re well-adapted to eating it, and capable of processing the fructose it contains. (Unless you are FODMAP intolerant – but that’s a different issue entirely.)

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  1. Interesting stuff, but I wonder to the degree we’re not taking into account behavioral/psychological aspects of this argument. Biology may, in the end, trump all, but behavioral patterns can influence biology. Their interaction suggests they may be on an equal playing field. I agree that in an isocaloric state we might be fine, but in calorie excess things might go awry. Can’t we easily achieve a hypercaloric state through the consumption of fructose heavy fruite? Especially given research suggesting that fructose results in less physiological reward than expected and may lead to overconsumption (Volkow et al.). In the lab I work I don’t see many of the kids or adults compensate for the excess fruit consumed by down-regulating consumption. Especially if the fiber content is low and perceived sweetness is high. I’m not trying to debunk the main point that fructose has not been proved to be uniquely fattening and that fruit should not be avoided, but wouldn’t it still be prudent to limit certain fruit types and quantity when trying to lose weight? Thoughts?

  2. I totally agree! Lustig demonized fructose and made alot of people in the paleosphere scared of fruit and more accepting of high glucose foods like sweet potatoes. Plus there is a less dramatic insulin response with high fructose foods like an orange compared to high glucose foods like bananas. What are your thoughts on the increased likelihood of fructose turning into AGEs?

  3. Chris,

    I’m wondering what you think of Mat Lalonde’s opinion of fructose. Maybe he’s modified his position recently, but from what I recall he recommends limiting fruit consumption and total fructose consumption to no more than 50 g per day.

    See here for example (In the comment section of one of Robb Wolf’s podcast posts):

    “As others have stated, fructose is limited in its usefulness to the body. Most of it is processed by the liver, kidneys, and fat cells. Glucose, on the other hand, can be used for fuel by any cell in your body. So you have the choice between fructose, a dose-dependent hepatoxin, and glucose. The choice is easy.

    The amount of fructose that can be tolerated depends on genetic variants as well as volume/type of training. Tolerated is the key word here meaning how much you can have without doing too much damage. If liver glycogen is completely full, than some fructose won’t hurt. In a sedentary population consuming a high-carbohydrate diet, some fructose does hurt. Observational studies have consistently shown that populations who consume more than 50 grams of fructose on a daily basis have problems with blood sugar control. The data is limited in its usefulness given its observational nature. Nevertheless, I like the 50g/day limit because it mirrors the limit for alcohol, which is also mostly processed by the liver. Now the limits don’t have to be identical since fructose and ethanol have different molecular weights but I still think it is better to try to keep fructose below 50g/day. Again, from a pragmatic standpoint, fructose is not a useful fuel and is potentially dangerous above a certain level. Why bother? And yes, you should minimize fructose from fruit. Some individuals seem to think that the vitamin C in fruit will some of the detrimental effects of excess fructose. Vitamin C does appear to have an effect on levels of uric acid (which was synthesized in response to fructose phosphorylation) but uric acid is merely one problematic aspect excess fructose consumption. Others seem to think that the fiber in fruit will prevent absorption of fructose.”

    • While the scientific evidence of record may seem somewhat equivocal concerning the impact fructose consumption may have on achieving a desired low body fat level, the science which examines the insidious effect fructose imposes upon blood uric acid levels, is less equivocal.

      Fructose metabolism can deplete ATP, and this implies a temporary inability to synthesize protein and eventually the breaking down of the phosphates that make up ATP result in the generation of a few substances, including lactic acid and uric acid. In an article in the October 2007 issue of the “American Journal of Clinical Nutrition,” scientists report that this process may raise uric acid concentrations by 1 to 4 mg/dL after consuming a large fructose-based meal. Normal uric acid levels are between 3 and 7 mg/dL. Abnormally high results with uric acid can lead to a diagnosis of diabetes, gout, hypoparathyroidism, kidney failure, leukemia and host of other serious medical issues.- “Journal of the American Society of Nephrology;” The Effect of Fructose on Renal Biology and Disease; Richard J. Johnson, et al.; December 2010

      Mr Kresser intrepidly states that
      “Fruit has been part of the human diet for longer than we’ve been, er, human. We’re well-adapted to eating it, and capable of processing the fructose in it”

      It may be problematic to cast fruit as a commodity, whereas a vast qualitative difference may have prevailed between the fruit species our ancestors consumed throughout long-term evolution, versus the petrochemical produced hybrid varieties of fruit that are provided by our commercial markets today. Further, relative qualitative differences between fructose and other nutrient compositions of contemporary fruit may be significant.

      As middle-aged recreational triathletes, I and four of my peers, tested fruit as a primary source of carbohydrate fuel several times over two years. The results of these trials revealed that fueling on fruit was abysmally unsustainable and unsuccessful. Consuming whole natural fresh fruits (dragon fruit, durian, banana, etc) comprising 30% to 40% of daily total calories, lead to elevated uric acid levels and pain and discomfort that was in some cases physically debilitating. Ultimately it was not until we supplanted the major portion of our whole fruit-based carbohydrate source with processed white rice in quantities of 300 to 400 cal per day and maintained only a maximum of 50 g carbohydrate from whole fruit, that our athletic and active lifestyles became comfortable and sustainable.

      It may be helpful to note, that there is a pervasive feeling among us that attempting to employ fruit as our sole carbohydrate source, posed a barrier to achieving a lower healthy body fat level. Where a couple of us had some visceral type waistline fat to lose, it seemed the whole fruit was not conducive to calorie deficit fat reduction. This may be because fruit is relatively slow to metabolize and does not adequately prevent metabolic slowdown while calorie deficit dieting. We were only able to maintain acceptable metabolic rates and achieve our body fat reduction goals by adding small portions of white rice to our deficit diets.

      Clearly, Paleontology reveals that our ancestors did not evolve consuming cereal grains (processed white rice included), yet the pragmatic obstacles with attempting to fuel on fruit, which the physically active and/or athletic person may be confronted with today, can seem to leave no other viable option.

      Incidentally, Mr Kresser’s posting from some time ago, which revealed problems with a low or no carbohydrate diet – the problems being hormone (cortisol) imbalance, is particularly valid and helpful. Especially for us athletically active persons, our practical experience tests proved that lowering our carbohydrate component below a certain threshold, can lead to accumulation of excessive body fat, insomnia, and other health disorders

      Sincere thanks for for the helpful contributions on this important and seemingly enigmatic topic.

      • Hi Nigel, I appreciate your polite and constructive input. The report by Johnson, et al identifies the following as potentially problematic: added sugars, sucrose, high fructose corn syrup, sugar-sweetened drinks, fructose-rich drinks, and “the administration of 200 g of fructose per day.” Whereas regarding fruits, it says:

        “Forman et al. was unable to find an association of fructose intake with hypertension in studies based on nurses and health professionals. However, in these groups, a large amount of fructose was from natural fruits, which are known to be high in antioxidants and flavenols that can block the pro-hypertensive effects of fructose in animals; in addition, ascorbate also lowers uric acid by stimulating renal excretion.”

        So doesn’t the take-away appear to be to avoid adding table sugar to your foods, processed foods made with added sugars, and sugar-sweetened drinks–not necessarily to avoid fruits?

        • Yes, theoretically whole fresh natural fruits should constitute a dietary virtue, yet in practical terms it seems athletes, especially athletes aiming to reduce body fat need adopt alternative sources of carbohydrate to fruit. At first I did not want to believe the thesis of the Paleo Diet for Athletes (essentially that endurance athletes need concentrated glucose that is rapidly metabolized and need diverge from a standard Paleo diet), but our practical trials have corroborated the validity of the principles presented. Likely healthy non physically active or modestly physically active persons could sustain adequately with fruit as the only carb. source.

      • Thanks for this great contribution Nigel, I for one appreciate you presenting your real world experiments and results.

        I don’t find it in the least bit surprising that you weren’t able to fuel yourself effectively with high levels of fruit, I found the same thing when doing the Yorkshire Dales 3 peaks a few months ago (I wrote up my experiences for a friends blog here: http://foodandfitness.co.uk/homemade-food-hills/#more-3255).

        Thanks again,

    • fructose is interconvertible with glucose (that’s why the GI of fructose is 20, not 0) and although initial pathways are separate, metabolism converges at the level of the triose-phosphates (three carbon compounds from the lysis step in glycolysis). The major problem with fructophobia is that it impedes trying to find out how fructose and glucose are really different. The attack on fructose is similar to the attack on fat which has produced, as they say, much heat, but not so much light.

      • Well said, Dr. Feinman. One oversimplification (demonization of saturated fat) has largely been replaced in the LC and Paleo spheres by another (demonization of anything containing significant fructose or glucose, especially fructose). Thanks for being a voice in the wilderness on this.

    • fructose is chemically more reactive than glucose. (If you know chemistry: it is inherently less reactive because ketose but exists much more in the open form). However, fructose is cleared from the circulation while glucose levels are maintained at a constant level. AGEs are due primarily to glycation by glucose, not fructose.

  4. The “forbidden apple” from the Garden of Eden, and concept of poison fruit seems to be debunked by you Chris! It never seemed logical to me that these delicious offerings from nature would be harmful- only in EXCESS, like most anything else in life, including water! Thank you for your measured approach to nutritional health!

  5. Hey Chris,

    I’ve been a long time reader of yours (first time commenter); I’ve often wondered what your position is on Ray Peat’s ideas regarding the possible protective effects fructose? I’d be really interested to hear you thoughts. Thanks!


  6. “The mice in the studies Lustig cites are eating huge amounts of fructose: up to 60 percent of total calories. You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.”

    Unless you’re a Ray Peat follower. Then, yeah, you might just have a problem… 🙂

    Thanks for adding some additional research to this issue, Chris!

    • Even Ray Peat followers would have a hard time getting fructose to be even 40 percent of their carbohydrate intake, let alone calories. Sure, Peat likes orange juice, sugar, and fruit, but all of those are 50-50 glucose and fructose. Ray also LOVES milk, and the lactose in milk contains no fructose. Agave Nectar (the only available food I know of that has a fructose percentage significantly higher than 50%) is not recommended by Peat.

  7. Chris, have you ever thought of really stepping outside the box and showing the potential benefits fructose has to offer?

      • Yeah, I just like to see people touch all sides of the scenario. I totally respect Chris for going against the paleo grain here. I have much more respect for people that don’t cling to a certain mentality and don’t preach the same message over and over again without really taking the time to see the other side. There is another side.

        Even if you don’t agree with Ray Peat’s dietary ideas, you should surely appreciate his understanding of endocrinology and amazing depth of knowledge/philosophies; such as this quote right here:

        “Once we accept that knowledge is tentative, and that we are probably going to improve our knowledge in important ways when we learn more about the world, we are less likely to reject new information that conflicts with our present ideas. The attitude of expectancy will allow us to apply insights gained at one level of generality to other levels. No particular kind of knowledge will have such authority that it will automatically exclude certain possibilities in another field of knowledge.”

        • I agree Tyler,

          I have noticed recently that many in the Paleo community don’t seem keen to comment on Ray Peat as he does go against some established Paleo ideas (Fruit Sucrose as the main calorie source). When looking at the evidence he produces to back up this idea, coupled with the existing long-term established misconceptions promoted by the food industry/governments/pharma firms I think it would be very difficult to disprove what he promotes.

          I think it is likely that the well respected Paleo experts are keeping quiet at the moment until they can make sense of his work.

          It is very clear to me that Raymond Peat cannot be ignored or dismissed, his arguments and the plethora of evidence he uses to back them up are strong. I also like the way he puts things into context.

  8. Are there any problems eating fruit with or after a meal as oppose to as a snack/on its own. I can’t find anything definitive on this issue.

    • IMO, it is best to eat fruits by themselves or least first. My first meal of the day is typically all fruits. My second and last meal of the day consists of fruits first and then some veggies.

  9. Chris,

    It’s never one thing, and that’s the problem with reductive science. Metabolism is flexible and adaptive, and in many ways, it seems completely lawless…it changes based on so many things—even in the course of a day. Unfortunately, unless we figure out some other effective language we are stuck with it, and hopefully enough common sense to figure things out.

    Your conclusions are correct, as I see it–nothing controversial about your recommendations–but the more important point, which I agree with, is not to demonize or rely on the ‘magic bullet’ because it really doesn’t exist. As I see it, fructose and sugar and flour and all the rest, are necessary preconditions (at least from my view from the bridge so to speak) but are probably not sufficient…

    It would be interesting to see though how many isocaloric diet include include a lot of HFCS, etc. and are really that healthy. But maybe…I guess you’d need to do the Twinkie diet for a year or even two not just a month?

  10. Keep in mind that modern fruit has often been bred for sweetness. And a fruit like apples isn’t even sweet (usually) when grown from seeds. Doesn’t that present a potential for increasing appetite and upsetting energy balance? But I don’t imagine that a bit of fruit now and then is a problem if it doesn’t lead to wanting more and more or produce other unwanted effects.

  11. As a relative newcomer to the paleo world (mostly following Sisson and Wolf), my understanding of fruit hasn’t been that it’s totally forbidden. Rather, that eating it is both highly-nutritious AND spikes your blood sugar. So, it’s good for you, but eating too much will make it difficult to tap into your stored body fat, thus making it difficult to lose weight (if that’s your goal).

    IOW: if you are slim, go ahead and enjoy a balanced intake of fruit; if you need to lose weight, limit your intake and give preference to lower-GI fruits like berries.

  12. Chris, I only partially agree with you regarding fruit and fructose. The problem – as with any foods or drinks – is the overconsumption of fruit, thus leading to excess fructose AND glucose (yes, fruit does contain both!). In the effort to eat “5-8” servings of fruits and veggies a day per the ADA, people tend to lean more towards fruit, thus overconsuming fructose, glucose, and yes, calories. Also, one must remember that the consumption of fructose & glucose in any form contributes to bacterial overgrowth of candida and yeast and other non-beneficial bacteria in the intestines. About 85-90% of people in the US have some form or SIBO (small intestine bacterial overgrowth), or candida, or yeast, and don’t realize it. In my practice, when I am working with someone who has digestive issues (GERD, IBS, Crohn’s, etc), or weight loss, the first thing I do is take them off everything and only have them eat veggies and protein. The results have been amazing and astonishing! After a 21 day period, we gradually add back fruits that are elss than 10-15 grams of fructose, and of course, appropriate grains such as quinoa and amaranth. By this time, most people are so comfortable with just the proteins, complex carbs, and healthy fats that they don’t really want to go back eating “the old way”, including overconsumption of fruits! And it goes without saying, NO ONE needs to be drinking sodas or fructose-laden anything!
    Thanks for your response!

    • I also treat patients with gut issues for fructose intolerance, but I think the 85-90% of people with SIBO or yeast is an overstatement. The prevalence of SIBO amongst people with IBS is only 40-45%, so I think it’s unlikely to be 85-90% in the general population. I run stool tests, breath tests and organic acids urine tests on all of my patients with gut issues, and a significant percentage of them do not have SIBO or yeast. (In these cases, it’s a gut-brain axis problem.)

      The consumption of fructose and glucose does not necessarily contribute to gut bacteria overgrowth. Monosaccharides are absorbed high up in the small intestine, and are not likely to become food for bacteria further down in the small intestine. Fructose is transported across the intestinal lumen with glucose when they occur in equal amounts. When fructose is in excess of glucose in a food, it will not be well absorbed and in that case I’d agree that it will feed pathogenic gut bacteria.

      I don’t think that overeating fruit causes metabolic problems or gut issues for the most part, but once someone is overweight or had digestive problems, I do agree that too much fruit can be problematic.

      • Pulling this info from the CDC:
        •Percent of adults age 20 years and over who are obese: 33.9% (2007-2008)
        •Percent of adults age 20 years and over who are overweight (and not obese): 34.4% (2007-2008)

        That accounts for 68% of the population. What percent of the population that have gut issues are not in that 68%? It seems to me that given the overweight prevalence, fructose is a problem for more that least 68% of the population, unless your definition of overweight is different than the CDC’s.

        I am personally still in the overweight category, but thankfully, no longer in the obsese category. Unfortunately, my favorite fruit is the tomato (especially used in cooking), which has a fair amount of fructose. But of course, nothing like apple sauce!

        • Wait a moment. Its not 68% of the population, it’s 68% of adults age 20 and over.

          • No, you don’t add them together. You take the percentages eitherof thewhole or use the separate populationsas a base to calculate total percentage.For example is I had five alcoholic drinksof 20,25, 35, 40 and 45% alcohol, I wouldn’t have had 160% alcohol, but, assuming equal volume, 32% wouldbe alcohol.

            • Joel! Ah! That’s taking an average of 5 mixed drinks. Terrible math.
              If you have ONE soda drink that has 25% glucose and 25% fructose, that’s 50% sugar. You do add them together, because the percentages are based off the same total. The populations are based off the same total, not two different populations that you must account for.

  13. “You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.”

    I disagree with the “ain’t gonna happen” portion of this statement – I once worked with a man who came in in the morning with a plastic SuperBig Gulp mug full of, IIRC, root beer. He got another one at lunch time (when he also ate a Snickers) and one more at the afternoon break. That’s three 44oz sodas by 4pm.

    He then blamed his giant waistline on “the new baby” and the fact that he didn’t go dancing twice a week anymore.

    • There are always outliers, but as the statistics I quoted in the article suggest, even people in the 95th percentile of fructose intake are not consuming that amount of fructose.

    • Many, many…I going to say most…drinkers of pop, drink easily 4 Big Gulps a day. They don’t drink water and rarely milk. MOST adults are also pop drinkers and/or koolaids & tea drinkers too. Hfcs galore.
      Maybe becuz you work with the small percentage if ppl who are health minded you don’t remember the epidemic of food ignorance that is the westernized world.
      Ppl are terrified of reducing fructose intake, even if they don’t recognize it as such.

    • I seriously laughed at the ain’t gonna happen sentence also. In my world that sentence could exist. However I’ve often been noted for being quite unrealistic lol
      If we could just outlaw possession of sugars as are tobacco and alcohol, the world would be hella different for the other 85% of Americans who daily torture their cells. Parents would have to do their drugs, the sugars and junk foods, without their kids imbibing and ingesting too.
      Now THAT ain’t gonna happen.

  14. If not sugar, what are the major food consumption contributors to the diseases of civilization among those who are not overweight? Does it almost all come down to bad grains?

    • Sugar (including fructose) absolutely contributes to western disease when eaten in excess, even in those that are not overweight.

    • There’s also the 300% increase in PUFA consumption over the past century. Combine excess PUFA, excess sugar, and excess empty calories from refined grain “foods” and we have what we have now..

      • only the adulterated industrially processed and nutritionally worthless PUFAs. PUFAs in their natural form are not a problem, but a remedy.

          • I remember a talk given by one of my Kinesiology teachers about a GNLD product called tre-en-en that is a blend of PUFA and sterols from wheat and rice grains. They came across it when researching how to combat chronic fatigue in the late 50’s (I think).

            This might be one example of PUFA’s being useful. I suspect another would be those PUFA’s we get naturally from eating lean, grass fed, grass finished meat. But then, we do get those in fairly small quantities, and they are balanced (when doing a good paleo anyway) between the n3’s and n6’s.

            Hope this goes some way to answering your question.


          • Oils lack the vitamins and minerals. Nuts contains the vitamins and minerals. Plus they are made by nature, not by men.

            LA(Omega 6) + B3, B6, magnesium, etc… = DGLA (anti-inflammatory) excellent for the skin.
            LA(Omega 6) taken without any vitamins and minerals = AA(very inflammatory in excess).

  15. Just showed the 60-Mins “Is Sugar Toxic” video to my class today. Good article above btw. Lustig in this piece does say that HFCS is the same as sugar, neither being good, though in the past I know he usually singled out fructose.

    • He’s not singling out HFCS, he’s singling out fructose. HFCS and sugar
      both have fructose in approximately equal amounts. I think part of the
      confusion comes from people confusing fructose with HFCS.
      Both these statements can be true at the same time:
      1) fructose is more harmful than glucose
      2) HFCS is not more harmful than sugar
      because fructose is not HFCS and sugar is not glucose but rather
      both are made of a combination of the two.

  16. This seems very sensible and balanced.

    However, there’s one phrase you used that gave me pause: “Glucose…[is] easily processed by the body.” Normally, yes, I’m sure that’s true, but in cases of chronic excess, insulin resistance becomes a factor, right? Under these circumstances, surely the body has an increasingly hard time of processing glucose?

    And the inevitably-high insulin levels will prevent fat from being used for food, surely? Thus causing a vicious cycle of hunger-and-sugar-craving, right?

    • Yes. This article wasn’t geared toward people with diabetes and other metabolic problems.

        • Agreed. It is true that people with diabetes used to be treated with lots of sugar. Sounds counter-intuitive but it worked.

          • No it doesn’t if you simply recognize you are a primate that has been eating starches and cheap oils, refined food and nothing with any type of electrical nature left in it.

      • Just curious about this one, but how exactly is “well tolerated glucose” defined? (Forgive my ignorace but I am onl a post-grad medical student, my experience is in molecular biology). Surely this is also dosage dependent, as glucosuria can occur in healthy subjects after high glycaemic loads? Is the difference between this and in patients with type 2 DM, simply tolerance of higher glucose dosage?

  17. Lustig is quick to point out that fructose isn’t bad unless in the context of excess calories, which is often the norm for those eating a standard western diet.

    It definitely does not apply to a whole food like fruit, which tends to be satiating and have a low energy density. Lustig specifically talked about that in the video.

    In the context of excess calories, fructose is “toxic” to the liver.

    • Lustig has been equivocal about this, actually. In other forums he has not emphasized the distinction between how fructose affects metabolism on isocaloric vs. hypercaloric diets. A lot of people are scared to eat fruit now because of his attack on fructose. Some may have misinterpreted his message, but I think in certain cases he has helped that along.

      • I understood Lustig and Mercola to be against all kinds of fructose including fruit and that made me skeptical of their claims.

        Thanks for clearing this up Chris.

        • Mercola is not against all fruits. He advises those with health issues or weight problems to cut out all fructose until they reach a healthy state. With healthy individuals, to avoid juice and eat the whole fruit, but limit total fructose to 25 grams per day.

          • You’re right, Sandy, and there is a very valid scientific reason for that. If you look at fat loss from a hormonal perspective, fruit is not helping the situation. Sure, there are plenty of good things about fruit, but helping with fat loss isn’t one of them.

            • There are dramatic differences between various fruits and fructose-containing foods. I seem to digest fruits worse than 99% of people, to the point where some people don’t even believe me when I tell them about the acne and foot/toe cramps I get from many fruits, but even I can eat an entire 17 oz (476g; 3.4 cups) carton of frozen wild Maine blueberries without significant problems and I’ve yet to encounter any reports of problems from wild berries by anyone on the Internet when I’ve asked or searched, and I haven’t seen a single study connect wild berries to obesity. It could be in part because a whole carton of wild Maine blueberries only provide 16.9 grams of fructose (according to data from Nutritiondata.com and http://www.livestrong.com)–well within Dr. Mercola’s limit, even at that large intake–and it also provides glucose that helps absorb the fructose, plus other things we may never fully understand. If wild berries give you problems, please let me know. I’d be interested to hear about how they affect others. The biggest (whole) fruit eaters on the Internet tend to be skinny rather than fat, and thus emaciation, rather than obesity, seems to be the biggest risk for heavy fruit eaters–especially for males. The sorts of fructose-bearing foods that seem connected to obesity are the industrially processed ones, like soda pops and manufactured fruit juices and fruit-flavored drinks, which was my experience, fwiw.

                • Nice try. I get those symptoms from organic fruits free of pesticides. I rarely eat nonorganic fruits.

                • organic fruit is full of pesticides, organic does not mean pesticides free. organic growers just dont use as many as non organic but it is as harmful as the rest. organic is a big business 😉

                • @nasta

                  So are you trying to say all fruit is equally bad because both conventional and organic have harmful pesticides, even if some don’t give me any noticeable negative effects whereas others do? Should we just completely ignore personal experience?

                • I’m sure all of Nasta’s food is grown pesticide free, has never eaten GMO corn or heavily sprayed wheat, all water from pure mountain springs, no antibiotics. Amiright?

                • @paelophil
                  absolutely not! i consider fruit good i just dont think that switiching to organic will solve pesticides/fungicides issues as its not pest./fung. free. i also think we shoud by no means ignore personal experienc but the opposite – focus on it. our bodies are the same yet so very different.
                  well first of all sarcasm is the lowest form of humor. And yes i do grow my own veg and fruit and when it comes to meat i think organic is better than non as it is applied in different way when it comes to animal. and yes julie one day i will have my own water and will be completely self sufficent and there is nothing wrong with it and if you wish you could be too 🙂
                  p.s. there is nothing wrong with modern medecine, antibiotics saved my life once but again i am trying to avoid pharmaceutical products as much as possible…

                • @peleophil
                  just a thought to your problem with fruit…have you tired combining diet? according to food combination principles fruit shoud be eaten on an empty stomach preferably in the morning…may help…one never knows 😉

                • @nasta
                  Yes, I have tried food combining and no-combining rules, including eating fruit on an empty stomach in the morning, with no noticeable difference. The negative effects I experience are not so much with fruit in general as with certain fruits. Given that even I can tolerate moderate quantities of certain fruits reasonably well, I suspect that lots of folks who think they can’t tolerate any fruit could actually tolerate certain lesser-known ones reasonably well. I don’t know for sure, though–just a guess. A small number of fruits dominate the US market and were chosen more for shipping hardiness, shelf life, cheapness to produce and sell, bigness and attractive appearance than healthiness.

                • Nasta: I was struck by the strong reactions to your comment in this old thread, but my close friend mentioned that there might be quite a few pesticides in organic produce as well. Any particular resources you have which would be good for reading up more about this?

              • It’s not like people are eating whole fruits. No, they are taking the sugary parts and drinking just that, the JUICE. Dr. Lustig doesn’t have problems with fruits or grains. What he’s saying is that because people are so afraid of fat, companies have taken fat and fiber out of fast food/chips and loading it with sugar. Lots of sugar. This causes obsesity and problems like gout. Not because people are eating too much meat, they are eating too much supermarket bread/cookies/chips that are loaded with sugar.

                He’s saying, eat fruit in it’s natural form, not in juice form. Look at traditional asian diet. It’s whole grains, whole veggies, meat and very small amounts of fruit. Fruit is still very expensive in Asia. Also, fruits in asia tend to be lower in sugar.

                Visit any school today and see if kids are eating whole fruits, GOD NO. They are drinking some frankieberry-sugar loaded juice or sugar loaded chocolate milk. Also note that when people say bread is bad, what they really mean is, bread is bad because food companies load all breads with too much sugar.

          • Is this the same Dr. Mercola that is against vaccination, says don’t eat fish, pushes his expensive supplements, and thinks animals are psychic?

            • I sure hope so! If you are eating fish from the Pacific Ocean, you better rethink your diet with all the stuff from Fukushima. BTW, animals are pretty smart. I wouldn’t be surprised if they are psychic 🙂

          • How is it possible to stay within 25g of fructose a day?
            What about the gorilla whose DNA is only about 4% different to ours.
            He lives mainly on fruit.

        • Lustig has never been against fruit. He points out that the fructose in fruit is accompanied with lots of fiber. His issues are with sugar added beverages and juices, Remember also he is a pediatric endocrinologist not just a scientist, and so he is seeing and treating children with obesity problems and is writing and lecturing from clinical experience. He has always been clear that it’s the dose (and lack of fiber) that makes the poison. and his shtick about fructose being toxic is just a way to underscore the way in which it is metabolized just like ethanol. It’s worth watching his original lecture and reading his book. I can imagine in the echo chamber of media interviews etc. distortions creep in. But the key points he makes hold true.

      • What do you make of Ray Peat? I have spent a lot of time recently reading everything he has written on his site + danny roddys site and the research seems really sound + there is so much of it spanning a such a long time I find it difficult to argue against his approach to eating.

        You are likely aware of the discussion between Paul Jaminet and Danny Roddy and it makes for some interesting reading.

        I am an athlete and have tried out Ray Peat style eating and seem to thrive on it. I am comsuming 2-3 litres of orange juice a day and at least 4 pints of milk along with seafood, cheese, liver, eggs etc.

        I would love to hear your views.

      • I have read his book _Fat Chance_ and have seen some videos of him on You Tube. I never got the message from him that eating fructose in the form of fruit is toxic. He has encouraged eating the whole fruit and not blending or processing it. The insoluble and soluble fiber together are what slows down the rate of flux of fructose to the liver. See pp. 133-134 in his book and this video at 8 minutes or so. http://www.youtube.com/watch?v=Rj8uQUkhEAg

      • I just finished watching all of Dr. Lustig’s videos in their recorded sequence and noted it wasn’t until his later presentations that he identified “excess intake” as a critical aspect of his thesis. Also, he presents some concepts in a lay-vernacular that are misleading. Passionate as he is, I’d be somewhat skeptical of his agenda-driven thesis.

        • He is guilty of alarmism for sure and perhaps some zealotry (he wants government involved, which I refuse to entertain). His message needs to stay focused where it is most likely to be true; with processed foods and drinks that have large quantities of sugar and HFCS added. But who isn’t advocating avoiding such food these days?

      • Regarding the paper you cited, Tappy & Le (2010), to say that it doesn’t agree with Lustig is not accurate. This quote is from the abstract:
        “The evidence is less compelling in humans, but high fructose intake has indeed been shown to cause dyslipidemia and to impair hepatic insulin sensitivity. Hepatic de novo lipogenesis and lipotoxicity, oxidative stress, and hyperuricemia have all been proposed as mechanisms responsible for these adverse metabolic effects of fructose. ”
        It then goes on to state that there is no evidence that HFCS is any more deleterious than sucrose – which is precisely the claim made by Lustig from clinical observation. Added to which, he also states that higher amounts of dietary fructose are the issue (stating that fruit is safer than fructose sweetened foods), and as we know “the dose makes the poison”, that fructose acts as a chronic toxin rather than acute, and the endocrine issues he notes (as regards insulin, grehlin and leptin secretion and feedback) are in fact correct.
        I jist think it’s good to be somewhat pedantic on these points, rather than polarising the issue.

      • Lustig said in the video “When God created the poison(fructose) he packaged it with the antidote (fiber)”. I got that fructose from whole fruit is waaaaay better than fructose as a food additive.

        That said, I appreciate the fact that you pointed out that Lustig was talking about mice, not humans.

    • What does it matter when the brain is going to tell you to drink another soda…