Researchers from the Monell Center in Philadelphia report that obese people who drank a fructose-sweetened beverage with a meal had triglyceride levels almost 200 per cent higher than obese people who drank a glucose-sweetened beverage with a meal.
Triglycerides are manufactured by the body from dietary fat and function as fat transporters. While normal levels of triglycerides are essential for good health, increased levels have been linked to a higher risk of cardiovascular disease.
"Increased triglycerides after a meal are known predictors of cardiovascular disease," explained lead author Karen Teff, PhD. "Our findings show that fructose-sweetened beverages raise triglyceride levels in obese people, who already are at risk for metabolic disorders such as cardiovascular disease and diabetes."
While the research may, on first glance, appear yet more bad news for soft drinks sweetened by high fructose corn syrup (HFCS), the researchers note that they used pure fructose, and this is typically is not used alone as a sweetener.
Campaigners against the HFCS ingredient point to epidemiological studies that have linked the consumption of sweetened beverages and obesity, as well as some science that claims that the body processes the syrup differently than other sugars due to the fructose content, leading to greater fat storage.
However, industry associations like the Corn Refiners Association (CRA) have repeatedly claimed there is no scientific evidence to suggest that HFCS is uniquely responsible for people becoming obese.
Indeed, the CRA has stated in the past that it is not justified to directly liken HFCS to fructose as HFCS consists of 55 per cent fructose and 42 per cent glucose.
The new study, published online by the Journal of Clinical Endocrinology and Metabolism, involved 17 obese men and women. The volunteers consumed two meals on different occasions. On both occasions they consumed a meal and a sweetened beverage. While the meals were the same on both occasions, the beverages were different, with one beverage sweetened by glucose, and the second by fructose.
Teff and her co-workers report that, while the triglyceride levels did increase in all of the subjects, consumption of the fructose-sweetened beverages resulted in a total amount of triglycerides almost 200 per cent higher over a 24-hour period than consumption of the glucose-sweetened beverages.
The researchers also report that the effect was especially pronounced in insulin-resistant subjects, who already had increased triglyceride levels.
"Fructose can cause even greater elevations of triglyceride levels in obese insulin-resistant individuals, worsening their metabolic profiles and further increasing their risk for diabetes and heart disease," said Teff.
The researchers noted that future work would seek to determine the quantities of fructose necessary to cause the triglyceride increase when it is combined with glucose in beverages, potentially making a truly relevant link between experimental and commercially-available HFCS-sweetened beverages. Additional studies will also explore the metabolic and health effects of long-term fructose intake, said the researchers.
Source: Journal of Clinical Endocrinology and MetabolismRapid Electronic Publication, available online 10 February 2009, doi:doi:10.1210/jc.2008-2192“Endocrine and metabolic effects of consuming fructose- and glucose-sweetened beverages with meals in obese men and women: influence of insulin resistance on plasma triglyceride responses”Authors: K.L. Teff, J. Grudziak, R.R. Townsend, T.N. Dunn, R.W. Grant, S.H. Adams, N.L. Keim, B.P. Cummings, K.L. Stanhope, P.J. Havel