For the past 30 years the U.S. obesity rate has risen, along with the increase in consumption of high-fructose corn syrup (HFCS). Americans now ingest at least 200 calories of HFCS daily. And all that sugar does more than expand our waistlines: According to a new study, adults who consume high levels of sugar (25 percent of their daily calories) have elevated risk factors for heart disease. The study of heart disease risk factors, high-fructose corn syrup, and sugar will be published in the Journal of Clinical Endocrinology and Metabolism in October. It was conducted by researchers at the University of California–Davis and in Japan.
THE DETAILS: In the small, short-term study, 48 adult participants between the ages of 18 and 40 limited their daily consumption of sugary beverages for five weeks. They were then divided into three groups, with each group consuming 25 percent of their daily calories as beverages containing sugar in the form of fructose, high-fructose corn syrup, or glucose, respectively. (Federal dietary guidelines suggest that Americans consume no more than 25 percent of their daily calories as added sugar.) Within two weeks, those consuming fructose or high-fructose corn syrup had increased blood concentrations of three known risk factors for cardiovascular disease: LDL cholesterol, triglycerides, and a protein known as apolipoprotein-B, which can cause plaque buildup in arteries.
WHAT IT MEANS: We spoke with Kimber Stanhope, PhD, the study’s senior author, and a research scientist in the department of molecular biosciences, School of Veterinary Medicine, at UC–Davis. She told us that she was surprised by the study’s results: She expected that the glucose in high-fructose corn syrup (high-fructose corn syrup is roughly half fructose, half glucose) would mitigate the effects of the fructose. Says Stanhope, “In 2009, we published results from a study which showed that consuming 25 percent of daily calories as fructose increased circulating lipids and lipoproteins in older, overweight, and obese adults, while consumption of glucose did not." So she expected that the effects of the half-glucose HFCS would be less than those of pure fructose. "But the changes in the lipoproteins were as high in subjects consuming HFCS as those consuming the purely fructose-sweetened beverages.” She says that more studies are needed to confirm this unexpected pattern, and to determine if it is a result of an effect of consuming fructose and glucose in combination.
So what exactly are the differences between all these different types of sugar? We asked Stanhope to break it down for us non-scientists. Here’s her primer on understanding sugar:
Fructose is naturally occurring in fruit (at levels of 1 to 8 percent) and honey (about 38 percent). Pure fructose is rarely used as an added sweetener.
Glucose is naturally occurring in fruit (1 to 7 percent) and honey (about 31 percent). Pure glucose is not commonly used as a sweetener, except for corn syrup (such as Karo’s), which is a glucose syrup made from cornstarch. Other commonly eaten foods that contain glucose (in the form of complex carbohydrates) are grains (for example, wheat, oats, barley, rye) and veggies (potatoes, squash, and beans). Complex carbohydrates consist of chains of glucose molecules, which are broken down to single glucose molecules during digestion.
Sucrose is made up of a glucose molecule attached to a fructose molecule; it’s naturally occurring in fruit (0.1 to 6 percent), sugar beets (17 percent), and sugar cane (10 percent).