Studying Glucose, Fructose

June 17/Drug Week -- "Absorbed glucose and fructose differ in that glucose largely escapes first-pass removal by the liver, whereas fructose does not, resulting in different metabolic effects of these two monosaccharides. In short-term controlled feeding studies, dietary fructose significantly increases postprandial triglyceride (TG) levels and has little effect on serum glucose concentrations, whereas dietary glucose has the opposite effects," investigators in the U.S. report.

"When dietary glucose and fructose have been directly compared at similar to 20-25% of energy over a 4-6-week period, dietary fructose caused significant increases in fasting TG and LDL cholesterol concentrations, whereas dietary glucose did not, but dietary glucose did increase serum glucose and insulin concentrations in the postprandial state whereas dietary fructose did not. When fructose at 30-60g (similar to 4-12% of energy) was added to the diet in the free-living state, there were no significant effects on lipid or glucose biomarkers.

Sucrose and high-fructose corn syrup (HFCS) contain approximately equal amounts of fructose and glucose, and no metabolic differences between them have been noted. Controlled feeding studies at more physiologic dietary intakes of fructose and glucose need to be conducted," wrote E.J. Schaefer and colleagues, Tufts University, Department of Agriculture.

The researchers concluded, "In our view, to decrease the current high prevalence of obesity,dyslipidemia, insulin resistance and diabetes, the focus should be on restricting the intake of excess energy, sucrose, HFCS, and animal and trans fats and increasing exercise and the intake of vegetables, vegetable oils, fish, fruit, whole grains and fiber."

Schaefer and colleagues published their study in the Journal of Nutrition ("Dietary Fructose and Glucose Differentially Affect Lipid and Glucose Homeostasis." Journal of Nutrition, 2009;139(6):S1257-S1262).

For additional information, contact E.J. Schaefer, Tufts University, School Medical, Cardiovascular Research Laboratory, Friedman School Nutrition Science & Policy, Jean Mayer Dept. of Agriculture Human Nutrition Research Center Aging, Lipid Me, Boston, MA 02111.

From the June 22, 2009, Prepared Foods E-dition