20 January 2013

What journalists should know before writing about fructophobia

"Pick your poison" Sugars by vavroom, on Flickr

In his new book, Fat Chance, Dr. Robert Lustig argues that "sugar is more toxin than it ever was nutrient." He writes that sugar is as addictive as cocaine, that it should be regulated like tobacco, and that children should be carded before having a soda. He compares the fructose component of sugar to ethanol. "Pick your poison," he writes, arguing that fructose will "fry your liver and cause all the same diseases as does alcohol." He also challenges energy balance (calories-in-calories-out) as the dominant paradigm of understanding obesity and and argues that sugar is harmful in ways beyond the calories it provides.

With statements as controversial as these, it's no wonder that the media, who tend to crave sensationalism to obtain readers or viewers, eat them up like candy. And Dr. Lustig knows what he's doing and just what to say to elicit attention. He's no stranger to the spotlight, as Elizabeth Weil writes in her article featuring the pediatric endocrinologist. The showman-doctor also knows just how to tell a classic falling-prey-to-cruelty story. He'd have his readers believe just what they want to hear: that their weight gain is not their fault, that the great evil monster of the food industry is putting addictive "poison" in their food in the form of sugar, and that the government is standing "idly by" letting it all happen. After reading Dr. Lustig's book, it's easy to understand why readers are entertained and maybe even enraged enough to give up on sugary sodas, cheese cake, and apple pie. But are the arguments Dr. Lustig makes in the book right or wrong?

Sparked by my ire of journalists buying into the sensationalism without so much as offering a contrasting view, I previously wrote about how Dr. Lustig's eyebrow-raising claims didn't appear to hold water. For example, one need only check the evidence from systematic reviews of human intervention trials (not rodents) to find that: 1) fructose has no significant effects on body weight, blood pressure, or uric acid when compared to other carbohydrates contributing the same amount of calories in the diet; 2) fructose in high doses providing excess calories increases body weight as expected from its contribution of excess calories and not because of any unique property of fructose; 3) and fructose at the levels normally found in fruit, which equals to around 10 grams per meal, is shown to improve glycemic control long-term. Does that sound like an ingredient that is "toxic"? I didn't think so and neither do most nutrition scientists who've reviewed the evidence. For these reasons, scientists lashed out against Dr. Lustig's inflammatory rhetoric and overstatements in a symposium sponsored by the Corn Refiner's Association at Experimental Biology last April. I wrote about the debate, which I dubbed the "Sugar Showdown", and then followed up with an interview with Dr. John Sievenpiper, a lead author of several systematic reviews and meta-analyses evaluating fructose's effects on health of the body, to bring more clarity to the subject.

Despite the push-back from his scientist-peers, however, it's evident that Dr. Lustig is pressing on with his mission to demonize sugar and his published book has gained him plenty of new attention in articles and interviews. I've found it difficult to keep up with it all and have lagged behind, having been busy with other projects (like moving to a new house). Fortunately, exercise physiologist and sports dietitian David Driscoll took up the charge to set the record straight on fructose around the World Wide Web. I'm indebted to Driscoll for nicely summarizing my own thoughts, pushing my blog article, and bringing my attention to other articles. And I would encourage any journalist or blogger who is writing about sugar, fructose, or Dr. Lustig's book first read Driscoll's comment and follow each of the links. He told me over Twitter that he posted the following comment, or ones like it, on at least 50 different sites over five days:
While Dr Lustig's theories and evidence may seem convincing to the general public and reporters, the real test is how well he performs with his fellow scientists!
He was certainly called out for overstating the evidence and poorly extrapolating rat research at a conference he spoke at earlier in the year - check out the Q and A video in the attached article by David Despain (as well as the other lectures)!
What research shows that it is fructose that causes addiction? At the Q and A at the Sugar Symposium, Dr Lustig was called out on this and one researcher showed that rats liked glucose based carbohydrates over sucrose, and another questioned the applicability of rat research to be extrapolated to humans!
Also a recent rat studied suggests that it might be the sweet taste and NOT the fructose (as they used an artificial sweetener) although the article title gets it wrong also!
The major issue with Dr Lustig's theory is looking at US Sugar intake over history - levels were still high in the early 20th century - so saying it is sugar is either an oversimplification or there is a threshold value that we have recently crossed. Methinks that it is a perfect storm of more sugar and less burning it up with physical activity!
I hope you get a chance to review these before the interview - especially the video lectures linked to within the article by David Despain
In my own reading of Dr. Lustig's book over the last few days, I've found that apart from the claims about sugar, the rest of the book is relatively tame. In fact, it reminds me of why I tend to hate popular diet books and find them boring. There is one chapter where Dr. Lustig calls out out insulin as "the bad guy," as Gary Taubes does, and I've discussed why this is shortsighted in my post "Good insulin, bad insulin: Its role in obesity". He also dismisses physical activity as having a participating role in weight management (although he does say it's good for you for other reasons); as I've written before, exercise is critical because of the role of skeletal muscle in consuming energy and determining metabolic rate. Mainly, however, the book regurgitates a lot of the same arguments are about what's wrong with the food system, some controversial and some not. Overall, many nutritionists would probably agree that Dr. Lustig is non-controversial. His recommendations for weight management are sound. He summarizes them by shortening Michael Pollan's "Eat food. Not too much. Mostly plants." to just simply "Eat food." He argues that if you cut out all processed foods and sugar, people are bound to lose weight. He calls for completely cutting out anything with a Nutrition Facts label, which denotes that it is a "processed food". It's a no-brainer that people who go to this extreme would likely lose weight from lack of contributing calories from those foods. But it's not the only approach one can take to lose weight.

One might ask, why all the fuss about scientific accuracy? What's the problem with the cause of getting people to limit intake of sugar if it leads to a common good of reducing obesity? My answer to people who ask me this is the same that other scientists have voiced, which is that singling out of any ingredient and to make it the scapegoat for the obesity epidemic is just distracting. It's not helpful to call sugar "toxic" and ultimately does nothing to change people's habits, except maybe causing them to forgo buying any food with high-fructose corn syrup for a while. In the end, people will still continue to eat too much, exercise too little, and gain weight.


Unknown said...

I have to say, I completely disagree. I've talked to Lustig and checked out a lot of scientific research on the topic. My own article on obesogens in Environmental Health Perspectives mostly focused on chemical obesogens (mostly EDCs) but in my interviews that didnt make it into the piece, I did research High-fructose corn syrup which is also an obesogen that can alter the epigenome of unborn children, according to some research. Here's a link to the PD of my article http://www.wendeeholtcamp.com/Obesogens-EHP.pdf

CarbSane said...

Nicely done David!

I have one question: Where is the academic press book on the topic? And all I have to say in answer to that is that he could not write one. Which to me is QED.

Are there no fact checkers at UC Davis that might have stopped his juggernaut of misinformation ... like, say at the UCDavis produced YouTube video level? For shame!

feinman said...

My original critique at http://wp.me/p16vK0-6W described fructophobia as a threat and an opportunity. If people use the book to find out about metabolism it will have been an opportunity. For example, the metabolism of fructose has hardly anything in common with the metabolism of ethanol but if the question is used as a way of finding out about how they are really metabolized that will be a big step forward. If we ask the really interesting questions: Glucose and fructose are interchangeable and they come together at the level of the three carbon compounds, the triose-phosphates. in those cases where fructose has a unique effect, how does the cell know where the carbons come from, or does it?. If we can use the fructose case to expand our knowledge of metabolism, that will be a great thing.

On the political end, if fructophobia can lead us into real use of carbohydrate restriction that will also be a benefit. I am concerned that when you give up on science, you never know where it will go so progress will probably be slow. The low-fat-cholesterol thing is dying a slow and agonizing death because of having given up on science early on.

feinman said...
This comment has been removed by the author.
feinman said...

I removed my previous comment because it was off-list to David and slightly off-topic and duplicated some of the above.

The question was about ethanol and fructose metabolism which is one of the great inaccuracies in Lustig's story. I mentioned that I had published an article showing the similarities and differences between the oxidation of ethanol as a food and oxidation in glycolysis in which both glucose and fructose participate. The paper suggested that ethanol metabolism was a good transition between organic and biochemistry.


Bottom line, if you know a little biochemistry: ethanol is oxidized to acetaldehyde which is then oxidized to acetic acid and that, in turn, is converted to acetyl-CoA and goes into the TCA cycle. The oxidizing agent is NAD+ as in many redox reactions in metabolism. I have a blogpost that may make this clearer http://wp.me/P16vK0-eY

The key oxidation in glycolysis is the conversion of glyceraldehyde-3-P to 3-P-glyceric acid, analogous to (but more complicated than) the second step in ethanol oxidation. The difference is that in glycolysis it is done in two steps. Why? The idea is that you learn in sophomore organic that aldehydes are easily oxidized. So NAD+ + ethanol is energetically very favorable. Where does the energy go? There is no mechanism for capturing the energy and it is wasted as heat. For glycolysis, however, instead of letting the oxidation run straight through, the enzyme (Ga-3-P dehydrogenase) uses the energy of oxidation to make a high energy compound 1,3-bisphosphoglycerate. This compound can then be coupled (catalyzed by 3-P-glycerate kinase) to the synthesis of ATP. So the combination of the two steps allows some of the energy to be captured.

Both fructose and glucose feed this reaction in glycolysis which is a different pathway from the ethanol reaction. Another important difference is that, at some point, the NAD pathway cannot keep up with high ethanol and it becomes a drug or toxin, if you like. There is a separate oxidative process, the P450 system, which might reasonably be called detoxification. No such system exists for fructose as far as I know. Calling fructose a toxin doesn't have an obvious correlate in metabolism.

daviddespain.secret said...

Thank you for this wonderful insight, Professor Feinman. If I get a chance, I'll write something up about it.

FYI - For those of you who don't know him, Richard Feinman is professor of Cell Biology at SUNY.

Diana said...

David, "illicit attention" - illicit means illegal. I think the word you want is "elicit." Sorry, I am a former copy editor.

daviddespain.secret said...


Oops! I knew that. I'll change it. Thanks for letting me know.


myocyte said...

Thank you. Very timely discussion.
Lustig's dismissal of exercise as important in weight control is counterintuitive and in conflict with population studies and everyday experience, but the calories burned during exercise are indeed fairly minimal. Can David or someone summarise the metabolic reasons why exercise is indeed important to prevent and treat weight gain?
Lustig also does not believe that Calories consumed should balance Calories burned. This is contrary to both the laws of thermodynamics and nearly all known metabolic and nutritional knowledge, yet he offers little evidence to support his extraordinary but appealing view.
I hope Australian journalists find your blogs before Lustig's book is released here.
(I have no conflicts of interest to declare)