Posted by Todd Zywicki:
HIGH-FRUCTOSE CORN SYRUP:
I have gotten comments from a number of readers on my passing comment
on high-fructose corn syrup ("HFCS") in my [1]prior posting on soft
drinks and obesity. I am not an expert on this particular aspect of
the debate--I just noted the point to express my acknowledgement that
the THEORY soft drink consumption might lead to increased obesity
seems plausible, and the focus of my post was on whether there is
empirical support for the argument (which I argued that there was
not). I stand by the latter point, but have gotten several interesting
comments that I thought were worth elaborating on the sceintific
point.
In the [2]update to that post I noted the clarification offered by
FROG of the physiology of HFCS metabolism and his questions about the
science.
Joe Hicks has alerted me to some other sources that discuss the
science that underlies the hypothesis that HFCS can lead to obesity.
The first is the [3]article that I had read that prompted my
recognition of the theory in the first place. It is by Bray, Nielsen,
and Popkin from the American Society for Clinical Nutrition. I was
going to post the abstract, but it is extremely technical (the article
itself contains some useful graphs that lay out the theory and
evidence in an accessible way).
A less technical discussion is also provided on Dr. Joseph Mercola's
web site, "[4]Six Reasons Why Corn Is Making You Fat."
As I said, I have no dog in this hunt, as the data appears to me that
soft drink consumption has been constant for the past 15 years and my
understanding is that the formula for soft drinks has been basically
constant over that time. On the other hand, HFCS has been added to a
large number of other foods during that period, as noted by Bray,
Nielsen, and Popkin, so if the effect is large enough it could play
some role in rising obesity. They observe in the article, "HFCS has
become a favorite substitute for sucrose in carbonated beverages,
baked goods, canned fruits, jams and jellies, and dairy products."
In my mind hard to believe that increased HFCS explains the whole rise
in obesity, however. First, increased obesity is a worldwide
phenomenon, so the HFCS model would have to be generalizable. Second,
there has been a dramatic increase in the obesity of dogs and cats in
the United States (estimates are that some 25-40% of American dogs are
overweight or obese), and I'm pretty sure they aren't drinking too
much Coke!
On the other hand, let me stress that it might still be appropriate to
ban vending machines at school, although it will do little to combat
obesity. I think a strong argument can be made that the problem with
vending machines is that they permit children to consume junk food
without parental supervision and on that basis alone it might be
appropriate to ban them. It is probably time to do something about the
terrible state of the school lunch program, which seems to be a
nutritional disaster (but I'll leave it to someone else to sort that
out).
Also, it should be noted (as many readers observed as well) that the
initial impetus for the substitution to HFCS was the United States'
ridiculous sugar agriculture policies, which jacked up the price of
sugar so much as to force a substitution to corn sweetners in soft
drinks in the first place (although I understand that HFCS is also
more chemically stable as well, which explains part of the
substitution, especially for processed bake goods).
Thanks to both Matthew Malewski and Joe Hicks for all this great info.
References
1. http://volokh.com/archives/archive_2004_08_21.shtml#1093448047
2. http://volokh.com/archives/archive_2004_08_21.shtml#1093448047
3. http://www.ajcn.org/cgi/content/full/79/4/537
4. http://www.mercola.com/2004/apr/10/corn_fat.htm
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