Trans fatty acids up type 2 diabetes risk: study

NEW YORK, Jun 06 (Reuters Health) - For women, lowering the risk of developing type 2 diabetes may be as simple as eating more salmon and mackerel and passing on dessert, the results of a recent study suggest.

Researchers report that the type of fat found in cookies, cakes and other processed foods can raise a woman's risk of diabetes, while polyunsaturated fat in certain types of fish and vegetable oils appears to lower the risk. Substituting foods rich in trans fat with those that contain polyunsaturated fat could reduce the risk of type 2 diabetes by about 40%, Dr. Frank B. Hu of Harvard University in Boston, Massachusetts, and colleagues report in the June issue of the American Journal of Clinical Nutrition.

"These data suggest that total fat and saturated and monounsaturated fatty acid intakes are not importantly associated with risk of type 2 diabetes in women but that dietary trans fatty acids increase and dietary polyunsaturated fatty acids reduce the risk," Hu's team writes.

According to the report, Americans consume about 3% of total calories from trans fat, which is produced when liquid fat such as oil is processed in order to make it solid at room temperature. Margarine, for example, is a major source of trans fatty acids.

Hu and colleagues reviewed medical and dietary data from more than 84,000 women aged 34 to 59 years who did not have diabetes, heart disease or cancer when the study began in 1980. At three points over the next 14 years, the researchers updated dietary information.

Results show that intake of total fat, saturated fat and monounsaturated fat found in nuts, seeds and avocados did not influence diabetes risk. But a 2% increase in calories from trans fatty acids raised the risk by 39% and a 5% increase in calories from polyunsaturated fat lowered the risk by 37%.

The authors note that trans fatty acids and cholesterol probably do not cause diabetes. Rather, these types of fat might make women who are already susceptible to the disease, such as those with insulin resistance, more likely to be diagnosed.

Patients with type 2 diabetes do not respond to insulin, the hormone that clears the blood of sugar after a meal and deposits it into cells throughout the body to use as energy. Insulin resistance, a condition in which the body begins to ignore the hormone's commands, is often a precursor to type 2 diabetes.

In other findings, women with high intakes of trans fat were more likely to smoke, less likely to exercise regularly, and had lower intakes of alcohol and folate--a B vitamin that may lower heart disease risk.

In an accompanying editorial, Canadian researchers stress that the results will need to be confirmed.

"If the authors' conclusion that a decrease in trans fatty acid consumption will substantially reduce the risk of type 2 diabetes is correct, the implications for the food supply are serious," according to Dr. M. Tom Clandinin and Michaelann S. Wilke of the University of Alberta in Edmonton.

Nonetheless, the study adds to an ongoing debate over the role of dietary fat in the development of type 2 diabetes. While excess body fat is known to contribute to the onset of diabetes, exactly how dietary fat influences insulin resistance and diabetes risk is not clear.

SOURCE: American Journal of Clinical Nutrition 2001;73:1001-1002, 1019-1026.

http://www.reutershealth.com/frame2/eline.html