The Corn Refiners Association, an agribusiness lobbying group representing producers of high-fructose corn syrup (HFCS), has been trying for years to convince individual consumers and the government that "sugar is sugar." One of its websites, CornNaturally.com, aims to convince processed food manufacturers that consumers really don't care about HFCS and that consumers are far more worried about sugar consumption than about the HFCS content of processed foods. The CRA even engages in some sleight of hand, stating that "as HFCS consumption declines, obesity and diabetes rates trend upward." Three things are notable about this claim. First, it's not exactly true: during the period from 1970 to 2000, both HFCS consumption and obesity rates rose in the US -- according to the CRA's own data! Second, a population-wide drop from roughly 38 pounds per person per year of HFCS to roughly 28 pounds per person per year still means that Americans are consuming a lot of HFCS -- and an increase in obesity rates from 31 percent of American adults to 35 percent of American adults during that same timeframe (2000 to 2010) falls far short of indicating an inverse relationship between HFCS consumption and obesity, particularly given the data from 1970 to 2000. Finally, the CRA says nothing about the effect of HFCS on any one individual.
Lucky for consumers, Dr. Lewis Cantley does! In a recent interview with BMC Biology, Dr. Cantley -- who holds a PhD from Cornell University, taught at Harvard University, and is now the director of the Cancer Center at New York-Presbyterian Hospital -- explains how and why the human body treats fructose differently from other forms of sugar.
Dr. Cantley has spent years researching the production of lipids by the human body, including the production of the oncolipid -- that's a fat linked to cancer -- phosphatidylinositol-3,4,5-triphosphate (PIP3). In his interview, Dr. Cantley responds to a question about the metabolism (breaking down in the body) of fructose compared with other forms of sugar: "The liver differentially metabolizes fructose and glucose [...] The liver does not have hexokinase, so it cannot phosphorylate fructose at the six position [...] In the liver, fructose [...] gets phosphorylated at the one position directly [...] and [...] becomes a substrate for aldolase, and it produces even higher levels of ATP and citrate that go on to make fatty acids." In fact, Dr. Cantley explains,
Now matter how much you've eaten, you will still make more fat if you eat fructose.
But that's not all: Dr. Cantley further explains, "There are two other things about fructose that make it different from glucose. One is that all the fructose you eat is cleared on its first pass through the liver.
In other words, the liver scarfs up all the fructose and immediately converts it to fat, while the glucose stays in the bloodstream for some period of time.
"That is good for the brain -- the brain loves to eat glucose. It's good for the muscle. But fructose doesn't actually supply any energy to your brain at all; it doesn't supply any energy to your muscle; it only gets stored as fat."
Dr. Cantley also has something to say about artificial sweeteners: "The way we've attempted to avoid this problem is by using artificial sweeteners. The problem with those is that a disconnect ultimately develops between the amount of sweetness the brain tastes and how much glucose ends up coming to the brain. So the brain figures you have to eat more and more sweetness in order to get any calories out of it [...]
And then you eat an entire cake, because nobody can hold out in the end.
"The only way to [...] break the addiction is to go completely cold turkey and go off all sweeteners -- artificial as well as fructose. Eventually the brain resets itself and you don't crave it as much."
Obviously, individuals would be better off consuming less sugar of all kinds, rather than more, above a certain (fairly low) threshold amount needed to maintain brain and muscle function. However, when choosing between cane sugar and HFCS, it's clear that cane sugar has a preferable metabolic profile. And this is true in addition to the fact that much HFCS is contaminated with mercury because of the unnatural process by which this processed ingredient is made.
Reading labels -- HFCS lurks in all sorts of products from "juice drinks" to bread -- is crucial to avoiding this problematic ingredient.