Q&A: High Fructose Corn Syrup: Special Culprit in American Obesity?

Newswise — High fructose corn syrup (HFCS) has been singled out as having special properties that make Americans fatter than sugar and other energy sources with identical calorie contents. But an analysis by the University of Maryland Center for Food, Nutrition, and Agriculture Policy (CFNAP), appearing online in the August issue of Critical Reviews in Food Science and Nutrition, says there isn't enough evidence to conclude that HFSC contributes to weight gain any more than any other energy source, including sugar and fructose. In the following interview, Maureen Storey, Ph.D., CFNAP director and a member of the study team led by Richard Forshee, Ph.D., discusses the analysis and the team's recommendations for further research on the HFCS question. Media may use all or part of this interview.

Q: Why is it thought that HFCS makes us fatter than other foods? Over the last 30 years or so, obesity has risen dramatically. Also, during this time, high fructose corn syrup production and use has increased and replaced sucrose (i.e., table sugar) in many foods and beverages. The hypothesis is that because obesity has risen along with the use of HFCS, this sweetener has contributed to the rise in unhealthy weight among adults and children. This hypothesis was based on the weakest form of evidence called ecological data. What that means is that during a particular time period, two things happened simultaneously. Obviously, many other changes occurred over the last 30 years that may contribute to obesity. There is also the misperception that HFCS is fructose, which it is not.

Q: Are all HFCS products the same? No. There are three types of HFCS products (HFCS-55, HFCS-42, and HFCS-90), but only HFCS-55 and HFCS-42 are commonly used as sweeteners. HFCS-90 is mainly used in the production of HFCS-55, but is seldom directly added to foods and beverages.

The composition of HFCS-55 (55% fructose and 42% glucose), in fact, is very similar to that of sucrose (50% fructose and 50% glucose). HFCS-42 (42% fructose and 53% glucose) actually contains less fructose than sucrose does.

HFCS-55 is used mainly in beverages, such as carbonated and non-carbonated soft drinks; HFCS-42 is used to sweeten a wide variety of foods.

Q: What research did you look at? We conducted a thorough literature search to identify several types of studies, including literature reviews, commentaries, ecological and epidemiologic studies, randomized controlled trials, and animal studies. We also developed argument diagrams that helped visualize the hypotheses that were being proposed for the role of HFCS in contributing uniquely to weight gain. Finally, to assess the potential impact of regular carbonated soft drinks on body mass index, we conducted original research using data from the longitudinal studies and the food availability reports available in the peer-reviewed literature.

Q: What were your conclusions?The expert panel concluded that HFCS does not appear to contribute to overweight and obesity any differently than do other energy sources, such as the sucrose it has replaced.

Q: What did your team recommend for future research? The expert panel identified many gaps in the research. First, there were no studies that examined whether HFCS (not fructose) is metabolized differently than sucrose.

Another priority is to update the USDA food composition and nutrient databases. Without this critical information, nutrition and toxicological research will be flawed by out-of-date data. Fructose levels in food products and actual fructose consumption is unknown. In addition, there are no chemical methods that can distinguish naturally-occurring dietary fructose from fructose added by manufacturers either as sucrose or HFCS.

To date, there are no data on any special vulnerabilities of sub-populations that may be predisposed to obesity. More research is needed to better measure energy expenditure and its importance to weight control and prevention of weight gain.

Finally, increased access to federally funded longitudinal datasets is needed so that researchers can replicate each other's findings.

Q: If it's not HFCS that's making Americans fatter at a rate that has people calling obesity an epidemic, what is causing such a rapid increase in overweight? There are many, many factors that are related to the weight gain observed in the U.S. population. No one factor, including consumption of HFCS, sucrose, or foods that use either sweetener is uniquely responsible. Weight gain is the result of an imbalance between the energy we consume (calories in) and the energy we burn through physical activity (calories out).

Q: Who funded your study and what was your obligation to them? Tate and Lyle provided an unrestricted grant to hold the workshop and that was the only obligation. No one from Tate and Lyle participated in the workshop nor did anyone from the corporation have any input into the literature search, development of the argument diagrams, design of the original research conducted by CFNAP, or the decision to publish.