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Why the new study on high-fructose corn syrup and weight gain is flawed

By Nicci Micco, March 26, 2010 - 12:04pm

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Nicci asks: Do you avoid high-fructose corn syrup?


I've read a few passing mentions that HFCS contains mercury, possibly a byproduct of the production, but it doesn't seem to be part of the conversation in general. I wonder why because it seems way more pressing an issue than the calorie issue.


03/26/2010 - 1:48pm

This particular study may have been poorly designed, but I don't think this means that HFCS is OK for consumption in the human diet. Robert Lustig, MD of UCSF's Center for Obesity and expert in neuroencrinology, explains the biochemistry of sugar vs. fructose in a lecture that can be viewed here That fact is they are not metabolized by the human body the same way, with fructose having long-term effects on the body that resemble chronic alcoholism. Therefore I believe its wrong to suggest that HFCS and sucrose are equivalent in their negative health effects.


03/26/2010 - 1:51pm

No wonder why we are all confused about nutrition. What are you telling us? This makes no sense. HFCS is bad yet not that bad, yet it's bad only when it's good???? Bottom line, avoid it, it is part of highly processed junk food. Watch "Food Inc." Thanks for confusing more people with this pointless article.


03/28/2010 - 12:06pm

According to Nicci Micco in a blog on Eating Well, Karen Teff of the Monell Chemical Senses Center found fault with our study of high-fructose corn syrup (HFCS) in rats. Here are her four points and our responses to them. I hope you find this helpful. Bart Hoebel, Princeton University

Comment #1: The solutions of HFCS and sucrose used in all the studies—there were a few—in the Princeton report provided different levels of calories. (The HFCS, in fact, was lower in calories.)

Response: It is correct that the solutions of HFCS and sucrose were not offered as calorically equivalent. We note this in the Methods section of the paper. However, it is important to note that the HFCS consuming rats in Experiment 1, the short-term (2-month) study, showed greater gains in body weight while taking in fewer calories of sugar compared to the groups consuming sucrose. This led us to hypothesize that there might be something different about the way HFCS affects the body. Thus, we conducted Experiment 2, the long-term (6 month) study, and measurements showed that increased triglyceride levels and increased body fat were seen in the rats with access to HCFS, but not sucrose.

Comment #2: In one of the studies, the authors reported that male rats had a higher body weight after being exposed to 12 hours of access to the HFCS plus their typical rat chow compared to 1) standard chow alone, 2) 12 hours of access to sucrose with chow, and 3) 24 hours of access to sucrose with chow. However, they did not report or do the statistics on the change in weight. Thus, this is meaningless and poorly controlled.

Response: One of the groups listed above is cited incorrectly; group 3 had 24 hours of HFCS and chow access (no sucrose access). As stated in the Methods section, the males in the three groups of Experiment 1 were “weight-matched”. That means the average (mean) weight of the rats in each group started out the same. Therefore the end-point body weights reported are in fact accurate representations of the mean body weight change. Ergo, the statistics were done on the appropriate measure. The result is meaningful and well controlled, given the use of not one but three comparison groups.

Comment #3: In a second experiment, they compared chow to chow-plus-HFCS for 24 hours and chow-plus-HFCS for 12 hours and found that access to the HFCS increased body weight. So what? Again, meaningless. This is like taking two groups of people, giving them the same diet but allowing one group to drink sweetened soda whenever they liked. Of course, they will gain weight because they are ingesting more calories. These findings have nothing to do with the controversy between sucrose and high-fructose corn syrup.

Response: The result is, in fact, meaningful. As cited in the Discussion section, we have previously shown that the rats are able to compensate for the excess calories obtained when drinking 10% sucrose by taking fewer calories of chow and thereby maintaining a normal body weight. Therefore, we thought it was interesting and important to report that long-term access to HFCS causes rats to become overweight, whereas access to 10% sucrose does not. While comparisons were made to sucrose in some of the studies, this was not the sole focus of the paper. Rather, we were interested in seeing the effects of HFCS on body weight and obesogenic characteristics, and there were other variables of interest that were studied (as described in the response to the next comment).

Comment #4: Finally, in a third study, they show body weight as a percent of baseline (this is appropriate) and show that rats who had free access to both chow and HFCS gained a tiny bit more weight than chow alone, 12 hours of HFCS or 12 hours of sucrose. They did not compare it to the control of 24 hours of access to sucrose.

Response: The statistical test (Repeated Measures Analysis of Variance) did show an overall significant difference between female rats with HFCS to drink 24-hr per day and the groups with chow alone or 12-hr access to sucrose, as described in the Results section. We did not compare 24-hr HFCS vs. 24-hr sucrose in this study because 1) in our previous studies (with both male and female rats) we have noted that rats with 24-hr access to 10% sucrose do not gain significantly more weight than chow-fed controls, and 2) in addition to comparing HFCS to sucrose, we were interested in the effects of limited (12-h) access to HFCS to see if it would cause bingeing that might enhance HFCS intake or body weight. Further, we chose to focus on assessing 12-h access as a variable because we did not know the effect of 12-hr vs. 24-hr HFCS access in female rats. This was of interest to us in light of the findings in Experiment 1 in males where we made that comparison, and because our laboratory has a long-standing interest in the effects of binge eating of palatable food. We explain and give the rationale for the choice of these variables in the Methods section.
So, yes the females drinking 24-hr HFCS showed a statistically significant increase in body weight. It is important and meaningful because these females had significantly heavier fat pads in the abdominal and uterine areas. They also had higher blood triglyceride levels than the other groups, which may have contributed to the body weight and body fat characteristics of obesity.

Our study in laboratory rats complements the growing body of literature suggesting that HFCS affects body weight and some obesogenic parameters. We cite in our paper additional evidence reported by other groups that supports our findings, and also acknowledge studies that suggest that HFCS does not affect body weight in ways different than that of sucrose. We acknowledge in the paper that at higher concentrations (e.g. 32%) sucrose has been shown to increase body weight. We are claiming, however, that at the concentrations we compared in this study, HFCS causes characteristics of obesity. The data show that both male and female rats are (1) overweight, (2) have heavier fat pads, particularly in the abdominal area and (3) have elevated circulating triglyceride levels.
For more information and references on this topic, as studied in both animals and humans, see a review published this year by George Bray, Curr Opin Lipidol. 2010 Feb;21(1):51-7."Soft drink consumption and obesity: it is all about fructose".


04/01/2010 - 10:25am

Thank you, Dr. Hoebel, for taking the time to respond to our blog. I have updated it with an Editor's Note informing readers that they can view your responses in the comments section.


04/01/2010 - 3:54pm

yes I do, I am a diabetic and I have to be careful.


04/01/2010 - 4:40pm

Yes, if I need to sweeten anything I use natural sweeteners like honey and sometimes sugar. It doesn't make any sense to the consumer to use corn syrup, only to the manufacturers - in the form of profit.


04/01/2010 - 4:40pm

Yes I do and for many reasons:

1. I do not agree with the way it is manufactured.
2. It makes things overly sweet
3. To my knowledge it is not naturally occuring in corn but must be created in the manufacturing process.
4. It is present in most foods that we should avoid or limit anyway - namely overly processed foods.
5. I don't agree with the politics behind how we overproduce corn that is not suitable for human consumption but then have to "do something" with it - so we make HFCS.
6. It can be made so cheaply that it is easy for food companies to add it to just about anything and often without most folks being aware that these foods are being "sweetened" for no reason - thus resulting in consumption of more daily calories than we need and leading to obesity and a whole slew of chronic medical illness that are disabiling us, killing us and making us broke (rising healthcare costs all around).
7. I try to set a good example for my friends, family, coworkers and patients by eating food that was put here on our planet for a reason - and that my great-grandmother would recognize as food! (and avoid man-made food from man-made substances - edible, yes - good for us, NO).

I could go on but that highlights my concerns and reasons for avoiding it.
I look forward to some "real" scientific studies in the future.

Jerri Jensen, MD


04/01/2010 - 4:48pm

YES! Like the Plague.


04/01/2010 - 5:43pm

I avoid it like the plague and since I have eliminated it from my diet, my incidents of allergies and overall colds have decreased significantly.


04/01/2010 - 5:50pm

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