Does High Fructose Corn Syrup Promote Type 2 Diabetes?

A new study published in the journal Global Public Health has refueled the heated debate about whether or not the consumption of high fructose corn syrup (HFCS) is responsible for the increasing global prevalence of Type 2 diabetes. According to lead researcher Dr. Michael I. Goran, "The study adds to a growing body of scientific literature that indicates HFCS consumption may result in negative health consequences distinct from and more deleterious than natural sugar," Dr. Goran's study was immediately criticized by Audrae Erickson, President of the Corn Refiners Association (CRA), who stated, “This latest article by Dr. Goran is severely flawed, misleading and risks setting off unfounded alarm about a safe and proven food and beverage ingredient. There is broad scientific consensus that table sugar and high fructose corn syrup are nutritionally and metabolically equivalent. It is, therefore, highly dubious of Dr. Goran – without any human studies demonstrating a meaningful nutritional difference between high fructose corn syrup and sugar – to point an accusatory finger at one and not the other. If this study shows anything, it is that there is an association between body mass index (BMI) and diabetes prevalence. Take for example, Japan, where the average BMI is 22.59, and Mexico, where the average BMI is 27.59. Even though Japan consumes more HFCS every year than Mexico, the prevalence rates of diabetes in Japan are about half of Mexico. This example alone shows that Dr. Goran’s hypothesis is totally flawed." And James M. Rippe, M.D., Professor, BioMedical Sciences, University of Central Florida (and consultant to CRA) notes that “Diabetes is a complex disease with many underlying factors. It is highly unlikely that one component of the diet is uniquely related to diabetes. There are well-established links between obesity and diabetes. That is where we should be focusing our attention rather than vilifying one component of the diet.”Certainly the CRA's criticism of research purporting that HFCS has some unique quality that promotes type 2 diabetes mellitus (DM) relative to refined sugar has some merit. And they are certainly correct that researchers like Dr. Goran seem more like advocates than objective scientists. When researchers try to spin their data in ways that their more objective colleagues can easily see goes beyond what their data can justify, they undermine the credibility of science. However, it is also clear that, while HFCS is certainly not the only dietary factor promoting weight gain, insulin resistance, and type 2 diabetes, it is certainly a contributing factor. We know that insulin resistance and its associated metabolic disturbances are caused in large part by excessive energy intake, weight gain, and inactivity. Reducing calorie intake and increasing physical activity improve insulin sensitivity even before any significant weight is lost. Over time, increased activity and a negative calorie intake lead to weight loss. This even more dramatically improves insulin sensitivity and reverses the metabolic syndrome (and often even type 2 DM as evidenced by data of type 2 DM patients who have had bariatric surgery and lost a lot of body fat). While weight loss can reverse insulin resistance, it cannot restore most of the beta-cell function that is invariably greatly diminished by the time type 2 DM is diagnosed. Indeed, eventually beta-cell function becomes so diminished that even losing a lot of weight cannot "cure" type 2 DM.Sugar and HFCS Both Promote Type 2 DiabetesSugar (sucrose) is a 50-50 mix of fructose and glucose. HFCS is typically a 55-45 mix and so has a tad more fructose than glucose. Research has shown that -- all things being equal -- more fructose relative to glucose adversely impacts metabolism in ways that likely contribute to the development of type 2 DM independently of total calorie intake. And we also know that some HFCS is up to 90% fructose, so it is clear that while Dr. Goran's thesis was a huge exaggeration of the facts, it is likely true that HFCS can be a tad worse metabolically than refined sugar. Of course, refined sugar is a calorie-dense nutrient-poor food and HFCS is in no way better nutritionally than table sugar. One of the main reasons America has become much fatter on average since the 1950s is that the total amount of sugars has been increasing -- particularly the proportion of those refined sugar calories coming from beverages. Back in the 1950s, a bottle of Coke was 6 ounces and today a typical small soda at the movie theater is 16 ounces. Back in the 1950s and 1960s, the average American consumed about 8-10% of their total calories from beverages, but today most Americans are consuming at least 2-3 times more calories from beverages. Beverages, particularly those that are mostly flavored sugar water, are known to provide a lot less satiety per calorie that the same amount of sugar consumed as a solid food instead of a drink (eg, jelly beans versus a Coke, Gatorade, energy drinks, fruit drinks, sweet teas, or even fruit juice). Beverage calories, particularly in those that are loaded with sugars, are playing a major role in promoting obesity and type 2 DM in the USA and around the world.Bottom Line: A narrow focus on the impact of either HFCS or sucrose becomes a fairly meaningless "debate" (fueled by the economic battle for market share) between anti-HFCS, the CRA, and the Sugar Association. Obviously, the increasing consumption of both these sweeteners combined is the problem. This is especially so when they are added to a growing number of sweetened drinks being consumed around the world. Both HFCS and sucrose are likely promoting obesity and type 2 DM.By James J Kenney, PhD, FACN