E xcess blood sugar may boost free-radical production

By Suzanne Rostler

NEW YORK, Aug 25 (Reuters Health) - Excess sugar in the blood appears to increase the production of free radicals--byproducts of normal metabolism that have been linked to aging and heart disease, US researchers report.

The finding may help to explain the increased risk of heart disease and circulatory problems in diabetics (who have high blood sugar), and in the obese. High sugar levels trigger increased free-radical production by white blood cells, leading to arterial damage and blocked arteries, the authors note.

The investigators found that a drink containing 75 grams of pure glucose (sugar) increased the formation of free radicals in healthy volunteers. The study results are published in the August issue of the Journal of Clinical Endocrinology and Metabolism.

"We believe that in obese people, this cumulatively leads to damage and may cause hardening of the arteries," Dr. Paresh Dandona, the study's lead author, told Reuters Health.

"Until now it was a mystery as to how in obese people there is a marked increase in heart disease and stroke," he added.

The researchers, from the State University of New York at Buffalo, gave 14 healthy people a drink containing the same amount of sugar (glucose) in two cans of cola. Six other people drank a water-saccharine solution. The investigators took blood samples before the drink and 1, 2 and 3 hours later.

Free radicals in the blood rose significantly 1 hour after individuals drank the sugar drink and more than doubled after 2 hours, the results indicate. Those who drank the water-saccharine solution showed no change.

The sugar drink was also associated with an increase in a part of an enzyme that promotes free-radical generation, and a slight (4%) decrease in levels of vitamin E, an antioxidant.

"The implication is that free-radical damage (leading to) atherosclerotic lesions is definitely mediated by nutrition," Dandona explained. "There is a link between the amount of free radicals and what and how much you eat."

The study findings may also help to explain why people with type 2 diabetes are at increased risk of heart disease, he said.

In type 2 diabetes, the cells fail to respond to insulin, the hormone that clears the blood of excess sugar. Excess sugar in the blood can lead to fatigue and headache in the short term, and heart disease, kidney failure and blindness over the long term.

SOURCE: Journal of Clinical Endocrinology and Metabolism 2000;85:2970-2973.