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Gary Taubes on “toxic” sugar

April 14th, 2011

A friend just forwarded the new Gary Taubes NYT Magazine article on Robert Lustig’s claims that sugar is “toxic.” It’s an interesting article, worth a read, and Taubes is reasonably circumspect in acknowledging the uncertainties in the current evidence. He starts with this acknowledgment:

The viral success of [Lustig's] lecture, though, has little to do with Lustig’s impressive credentials and far more with the persuasive case he makes that sugar is a “toxin” or a “poison,” terms he uses together 13 times through the course of the lecture, in addition to the five references to sugar as merely “evil.”[...]

His critics argue that what makes him compelling is his practice of taking suggestive evidence and insisting that it’s incontrovertible. Lustig certainly doesn’t dabble in shades of gray.

Indeed, that’s precisely what’s at issue with Lustig’s lecture: not whether sugar is a problem, but whether it’s the problem. And to make that case, Taubes stacks the deck with statements like this:

The conventional wisdom has long been that the worst that can be said about sugars of any kind is that they cause tooth decay and represent “empty calories” that we eat in excess because they taste so good.

Who the heck claims this? (In journalistic jargon, phrases like “The conventional wisdom has long been…” are known as “weasel words,” because they allow you to make statements that help your argument without finding anyone stupid enough to actually say them.) It’s a convenient distortion, because it lends some misplaced novelty to the “Men Land on the Moon!” discussion that follows, about the links between sugar and metabolic syndrome. Come on, we’ve been talking about “glycemic index,” in which glucose is assigned the nominal maximum value, since the early 1980s. This is an important topic, and perhaps one that not everyone fully appreciates, but it’s tangential to Lustig’s central claim that sugar (and fructose in particular) is a “toxin.”

The central question here is really about dose. Is sugar “unsafe at any dose,” as Ralph Nader might put it? Or is it only unsafe when consumed to excess? And if the latter, what constitutes “excess”? To his credit, Taubes makes this point, though he weakens it by putting it in the mouth of someone he identifies as a lobbyist for the corn refining industry:

[S]ugar and high-fructose corn syrup might be toxic, as Lustig argues, but so might any substance if it’s consumed in ways or in quantities that are unnatural for humans. The question is always at what dose does a substance go from being harmless to harmful? How much do we have to consume before this happens?

Much of the rest of Taubes’s article explores how much sugar we’re now eating, how much it has increased, and how diseases like diabetes and cancer have increased in parallel. It makes a strong case for eating less added sugar — pretty much exactly the same case that Taubes made in his 2007 book Good Calories, Bad Calories, as far as I can tell. Heck, I was convinced in 2007, and I’ve been very conscious of my sugar intake — along with other highly refined carbohydrates — ever since then. What I don’t see here is any reason to be more scared of sugar than I was before on the basis of Lustig’s “sugar is a toxin” argument.

Taubes describes the mechanism of fructose’s action as follows:

In animals, or at least in laboratory rats and mice, it’s clear that if the fructose hits the liver in sufficient quantity and with sufficient speed, the liver will convert much of it to fat. This apparently induces a condition known as insulin resistance…

Again, scary stuff. But how is this different from, say, glucose, or even refined carbs from white bread, which are thought to stimulate insulin resistance if they enter the body “in sufficient quantity and with sufficient speed”? If we’re concluding that fructose is “toxic,” shouldn’t we also conclude that glucose and white bread and all other refined carbs are too? Oh wait, that’s what Gary Taubes proposed in 2007. So what has Lustig added? Fructose causes the same problems as other foods, but through a different biochemical pathway.

What would get my attention is evidence that cumulative exposure to fructose — independent of the rate of intake — accumulates over time to produce problems. In other words, does eating 50 pounds of sugar spread out over 30 years ultimately produce essentially the same bad effects as eating 50 pounds of sugar in a single year? Or is it only a problem when the dose comes “in sufficient quantity and with sufficient speed”?

To be clear, I have no doubt whatsoever that Lustig is right that we eat too much sugar and it’s causing health problems. I just wonder if there’s actually anyone in the country who didn’t already think that.

  1. rick
    April 14th, 2011 at 18:54 | #1

    I love the way you write–, skeptical, smart, and sharp. Respects the reader. And I
    admire the “wrong, wrong, wrong.” All good, and keeps me as a reader. Your site is
    part of my daily routine now.
    Some folks might think me a shill, but they’d be wrong, so you can delete
    this after you read it to avoid that impression if you prefer, its just to let you know we are out here.
    Thanks.

  2. Tom Maguire
    April 14th, 2011 at 19:38 | #2

    “If we’re concluding that fructose is “toxic,” shouldn’t we also conclude that glucose and white bread and all other refined carbs are too? Oh wait, that’s what Gary Taubes proposed in 2007. ”

    I have lent my copy to a friend but I have a strong recollection that Taubes identified the likelihood of a two-step process. In step 1, “something” (sugar specifically or excess carbs generally) provokes insulin resistance; in step 2, all easily digestible carbs become problematic for the insulin-resistant.

    Taubes was trying to work around the fact that some groups (like the Japanese) have high carb consumption without obesity. One explanation would be that since they avoid the sugar of step 1, they avoid the problems of step 2.

    Put another way, I thought Taubes was quite clear that he was unclear as to what caused insulin resistance in the first place; once people have developed insulin resistance, avoiding carbs becomes the obvious next step.

    Of course, I can’t trust my memory – too many years of pasta and sweets…

    That said, as a public policy matter world leaders cannot endorse a diet free of grains, rice and potatoes,or how wold the world eat? But cutting waaaay back on sugar would only upset Coca Cola. (Ooops, did I say “only”?)

  3. Lurker
    April 14th, 2011 at 20:53 | #3

    “I have no doubt whatsoever that Lustig is right that we eat too much sugar and it’s causing health problems. I just wonder if there’s actually anyone in the country who didn’t already think that.”

    I do NOT think that.

    Now, if we rephrase that first sentence to “I have no doubt whatsoever that we eat too much and it’s causing health problems.” – THERE! That I can agree with.

    HFCS is a great post-endurance-exercise product. Refills liver glycogen and muscle glycogen and metabolizes faster than glucose alone.

    De novo lipogenesis of carbohydrate isn’t as easy as Taubes and Lustig appear to think it is. Primarily ALL of the fat that you would gain from “eating too much sugar” is actually just all of your dietary fat being directly stored as fat while your body burns primarily carbs in the presence of a plethora of carbs, and not carbs being converted to fat.

    It’s a simple issue of efficiency and prior circumstances. If you’re liver and muscles aren’t carb-loaded, guess what, excess calories from carbs go there first. Only in the presence of fully-carbed liver and muscles will your body even START the expensive caloric process of de novo lipogenesis. Meanwhile, if you’ve hit your requirement of EFAs and have extra fats in the diet and too many calories intook Vs. what you’re burning, it’s really easy for your body to store incoming fat as fat.

    Likewise a low-carb diet can still pack on the pounds if you eat too many calories, even though your body’s low on carbs and burning lipids and ketones, if you have a caloric surplus it’ll store the excess calories as fat. :-)

    Look at any fatty’s diet! They are NEVER eating super-low-fat and high-sugar! It’s darn near impossible to do so, unless you figure they’re eating super-low-fat and getting all their carbs from sodas, because they’re ain’t too many low-fat sugary snack foods.

    So we eat TOO MUCH (sugar amount per se is not important) and get fat as a result.

    The insulin-resistance problems are a result of (1) too much visceral fat, and visceral fat is an extremely hormonally active organ, and (2) no exercise. Reductions in VF or increases in exercise promote greater insulin sensitivity regardless of carb amounts in the diet …

  4. alex
    April 15th, 2011 at 03:51 | #4

    @rick Thanks for the kind words! I certainly won’t delete your comment – heck, I’m going to frame it! :)

  5. alex
    April 15th, 2011 at 04:16 | #5

    @Tom Thanks for the comments.

    “Put another way, I thought Taubes was quite clear that he was unclear as to what caused insulin resistance in the first place…”

    Yes, and to his credit, even in the latest article he makes it clear that he’s talking about hypotheses and “suggestive evidence” rather than firm conclusions. You’re right that, if fructose ends up being identified the sole cause of insulin resistance, that does represent an advance on Taubes’ 2007 thinking. It just doesn’t seem like a change that produces much practical difference: if he previously thought it was “sugar specifically or excess carbs generally,” then he was already shunning fructose. I guess the difference is he’d now be able to chow down on as much glucose as he wants! (But it would take an awful lot of solid evidence to convince me that all the evil resides in fructose and we can mainline “non-toxic” glucose with no metabolic repercussions.)

    “Taubes was trying to work around the fact that some groups (like the Japanese) have high carb consumption without obesity. One explanation would be that since they avoid the sugar of step 1, they avoid the problems of step 2.”

    Well, if we’re going to wade into the epidemiological morass, it’s worth noting that the average fruit consumption in Japan is about 100 pounds per person per year. All this fructose doesn’t hurt them in the context of fruit because fruit has fibre, Lustig argues. But isn’t that just another way of saying that fructose only hurts you if it enters your system “in sufficient quantity and with sufficient speed”?

    Just today (if you’ll pardon the aside), I was reading another interesting NYT mag article, on the nature of evidence in the cellphone/cancer debate. Referring to the difficulty of comparing animal and human experiments (very relevant here!), the author invokes the 16th-century physician Paracelsus, who said, “It is the dose that makes the poison.”

    To me, that’s kind of what we’re arguing here. To justify Lustig’s hyperbole, I’d like to see evidence that fructose is toxic at significantly lower doses than many of us (but not @Lurker!) have already been assuming. Otherwise, he’s like the guy arguing that cardio exercise gives you heart disease — which might be true in certain contexts, but is misleading as a blanket statement.

  6. alex
    April 15th, 2011 at 04:29 | #6

    @Lurker
    Well, I take it back then! I guess not everybody agrees that sugar is problematic. :) And I certainly don’t claim to know for sure who’s right.

    “I have no doubt whatsoever that we eat too much and it’s causing health problems.”

    I can agree with that too. The question is, why are we eating too much? I tend to agree, to an extent, with people who talk about an “obesogenic environment” influenced by a range of social, technological and environmental factors. Is increased fructose intake a factor because, as Lustig argues, it doesn’t stimulate satiety in the same way that glucose does? Maybe. It wouldn’t surprise me. But I don’t see it as THE contributor — just one of many.

  7. Jennifer
    April 16th, 2011 at 10:46 | #7

    “To be clear, I have no doubt whatsoever that Lustig is right that we eat too much sugar and it’s causing health problems. I just wonder if there’s actually anyone in the country who didn’t already think that.”

    I just posted a little “sample menu” on my FB that a parent might typically feed a child on a average day. It contains 151 grams of sugar (added and naturally occurring). Is this too much? I would say that MOST people don’t realize how much sugar they are giving their kids. The Canada Food Guide recommends juice as the equivalent to eating fruit. It is loaded with sugar. The guide also recommends giving your kids chocolate milk as the equivalent of white milk – it’s served in schools.

    So, while “everyone knows” sugar is bad for you if you eat too much, the majority don’t know what “too much” is. And they don’t realize that all the sweet drinks can cause fatty liver disease and diabetes. I have a friend who developed fatty liver disease, and he doesn’t drink any alcohol – just lots of juice.

    Here is the menu I made up – it’s not supposed to be “healthy” necessarily, but just reflect what a busy parent might give their kid on an average day, and it contains 35 teaspoons of sugar:

    Breakfast: corn bran, milk, apple juice
    Snack: banana
    Lunch: wonder bread, tuna, minigo, milk, kashi bar
    Snack: orange
    Supper: spaghetti, prego sauce
    Dessert: 2 cookies
    Snack: mixed berries and honey

  8. Harry
    April 16th, 2011 at 23:39 | #8

    A problem I had with GT’s article is his juxtaposing of the ‘sugar/fructose is bad’ with the ‘too much insulin secretion is bad’ (in this articles he focuses on the putative link between insulin secretion and cancer no less!).

    As we all know, fructose is the one saccharide that DOES NOT provoke an insulin response.

    If anything, GT’s promotion of Lustig’s fructose concerns refutes his own “glucose consumption > insulin secretion > insulin resistance > obesity” hypothesis.

    This article seems to suggest just the opposite (i.e. that “fructose is the problem” and “too much insulin is the problem” are mutually supportive).

    Cheers
    Harry

  9. alex
    April 17th, 2011 at 00:41 | #9

    Harry — I agree entirely about the conflation of the speculative “fructose is bad” with the rather obvious “insulin resistance is bad” train of thought in the article, as if the evidence for the latter supports the former.

    That’s also an interesting point about the contradiction between Lustig’s hypothesis and Taubes’s original argument. Of course, it’s perfectly reasonable for Taubes to revise his thinking in light of new evidence. He may now think that (as Tom Maguire suggested above) fructose causes the initial problems with insulin resistance by damaging the liver, after which too much insulin (associated with carbs more generally) becomes the issue.

  10. Harry
    April 17th, 2011 at 09:39 | #10

    I don’t think he’s revised anything in terms of the carbs>insulin secretion>insulin resistance>obesity hypothesis. This is not surprising, as it has formed the basis for half of his first book and most of his recently released second book on this topic.

    I’m sure there is some hybrid hypothesis that can be fashioned so as to implicate both fructose-provoked IR and carb-provoked hyperinsulinemia>obesity…but it certainly doesn’t naturally fall out of the evidence that Taubes has focused on thus far.

    Just another little (but important) point; Taubes would have many fewer detractors if all he argued was that insulin resistance was bad…he actually argues that insulin secretion is bad insofar as it inevitably provokes IR (presumably above a certain threshold; which he, of course, never stipulates).

    Cheers
    Harry

  11. Phil Koop
    April 18th, 2011 at 17:03 | #11

    I finally got around to reading this Taubes article on the weekend (the print edition is a Sunday morning ritual.) I rolled my eyes at the same passages that you have selected, and more besides. This sentence in particular wound me up “a common assumption at the time was that if one hypothesis was right, then the other was most likely wrong.” Since this is essentially Taubes’ modus operandi, I thought it was a bit rich.

    However, you have backed me into the uncomfortable position of supporting Taubes. I really didn’t think that the overall impression conveyed by the piece was egregiously bad by journalistic standards. Perhaps that merely reflects my low expectations. But I note that there has been sufficient research into glycemic index to positively suggest that it is NOT the key. See this list, for instance: http://wholehealthsource.blogspot.com/2009/03/its-time-to-let-go-of-glycemic-index.html.

  12. alex
    April 19th, 2011 at 00:50 | #12

    @Phil Koop
    “However, you have backed me into the uncomfortable position of supporting Taubes.”

    My, how things change! :)

    I didn’t think Taubes’s piece was egregiously bad either. Magazine pieces, by definition, are expected to argue a point of view rather than dispassionately weigh evidence — that’s exactly what Taubes did, and what he told us on the first page (of the web version) that he was going to do. That’s fair enough — I just wasn’t convinced by the argument he advanced.

    My point in mentioning the glycemic index was independent of whether it’s “right” or “wrong.” The point is that it’s a concept that has been widely discussed for several decades, so suggesting that “The conventional wisdom has long been that the worst that can be said about sugars of any kind is that they cause tooth decay and represent ‘empty calories’” is misleading. (Though Lurker’s comment above shows that there certainly are people who do hold that view!)

  13. April 19th, 2011 at 18:59 | #13

    @Lurker

    Seems almost all “diet” foods are high sugar, low fat. Remember Snackwells?

  14. Sid Brechin
    February 17th, 2012 at 19:15 | #14

    A simple way to prove him wrong. If your blood sugar level hits zero, your DEAD. See if he can find a single example otherwise.

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