Consumption of fructose, usually in the form of high-fructose corn syrup (HFCS), has been suggested as one of the underestimated causes of the increased incidence of obesity/metabolic syndrome in the U.S.
Given the magnitude of the issue, Medscape covered this report, “Fructose but Not Glucose Consumption Linked to Atherogenic Lipid Profile,” from a presentation at the recent meeting of the American Diabetes Association by Peter J. Havel, DVM, PhD, and colleagues at the University of California at Davis Department of Nutrition.
In this small trial, 23 normal volunteers were first given an energy balanced diet of 30 percent calories from fat and 55 percent complex carbohydrates for 2 weeks. The group was then randomized to receive drinks containing glucose (13 subjects) or fructose (10 subjects) that comprised 25 percent of their daily energy needs for 8 weeks.
Relative to baseline, 24-hour postprandial triglyceride profiles were increased by 212% ± 59% in the fructose-consuming group (P < .0001). In contrast, levels declined by about one third (-30% ± 23%) in the glucose-consuming group. In addition, fasting plasma levels of low-density lipoprotein cholesterol (LDL-C); apolipoprotein B; and small, dense LDL-C, as well as postprandial levels of remnant lipoprotein (RLP)-triglycerides and RLP-cholesterol, were all significantly increased (P < .01) in the fructose group. By comparison, these levels remained unchanged in the glucose group.
Fructose-consuming participants also demonstrated increased plasma concentrations of the atherogenic risk factors oxidized LDL-C (P < .0001) and intracellular adhesion molecule (P < .05), but those consuming glucose did not.
"It is known that fructose, after being metabolized by the liver, is more likely to go into a lipogenic pathway than glucose," Dr. Havel noted. "So these results were not surprising to us, but the magnitude of some of the changes was striking," he added.
Indeed. I was blown away by the tremendous increase in plasma triglycerides with the fructose diet. However, the rest of the article notes that another (uncited) study showed no such changes when fructose comprised 17 percent of total calories. Keep in mind that this report is from a meeting presentation and has not been subjected to stringent peer-review; I’ll be interested to read the discussion of the ultimate full-length manuscript.
Of course, the Corn Refiners Association would refute this study by saying it did not investigate HFCS but rather pure fructose, not a fair comparison since the most commonly used form of HFCS (known as HFCS 55 in the biz) is about 55 percent fructose and 45 percent glucose. They may actually have a point here since regular table sugar, sucrose, is a disaccharide composed of one molecule each of glucose and fructose.
The question that plagues this research area is whether the growing (pun intended) obesity epidemic since the 1970s is due to HFCS or simply our overall increase in consumption of all sweetened beverages. I remember when Coke used to come in 8 oz bottles; now you can buy a 44 oz Big Gulp, or at least an average 20 oz bottle. The HFCS issue is also entangled with public aversion to genetically modified foods, including corn, and the fact that large corn-processing companies benefit from subsidies unavailable to conventional sugar cane producers.
Regardless of whether HFCS is more problematic than glucose or sucrose, the only sure way to reduce one’s risk of weight gain due to HFCS is to replace sweetened beverages with good old water.
(Source: American Diabetes Association 67th Scientific Sessions: Abstract 0062-OR. Presented June 23, 2007.)