By E. J. Mundell

NEW ORLEANS, Apr 22 (Reuters Health) - An omega-3 fatty acid found in fish oil appears to improve insulin function in overweight individuals who are vulnerable to type 2 diabetes, researchers report.

Three months of daily supplementation with docosahexaenoic acid (DHA) produced a "clinically significant" improvement in insulin sensitivity in overweight study participants, according to Dr. Yvonne Denkins, a nutrition researcher at the Pennington Biomedical Research Institute, Louisiana State University in Baton Rouge. She presented the findings here Saturday at the annual Experimental Biology 2002 conference.

More than 9 out of 10 diabetics have the type 2 form of the disease, where the body's gradual failure to respond to insulin can cause blood sugar levels to rise to dangerous levels.

Previous population studies have suggested that fish oil might help protect against diabetes. "There were epidemiological studies on the Greenland Eskimos, a population of people that eat mainly whale blubber," Denkins pointed out. "These are people that are overweight, that should be diabetic and have heart disease, but they do not. The scientists that studied them thought it was probably because of what they eat, and they found that it was the omega-3s."

In their study, Denkins and colleagues had 12 overweight men and women, aged 40 to 70, consume 1.8 grams of DHA at breakfast for 12 weeks. While none of the study participants had full-blown diabetes, they all suffered from insulin resistance--a pre-diabetic condition in which the body fails to efficiently respond to insulin.

Using blood tests taken at the start and end of the study, the researchers assessed changes in each person's insulin resistance.

"We did see a change in insulin sensitivity after 12 weeks of DHA supplementation," Denkins told Reuters Health. A full 70% of the study participants showed an improvement in insulin-related function, she said, "and in 50% it was a clinically significant change."

Denkins stressed that the small size of the study sample means that the results remain preliminary, and diabetics should never replace their medications with any dietary supplement, including fish oil. Individuals considering upping their intake of fish oil should also consult their doctor beforehand, especially if they are being treated for any cardiovascular condition, she added. This is because DHA has a slight blood thinning effect.

Nutrition experts currently recommend a daily intake of 0.6 grams of omega-3 fatty acids, preferably from fish. According to Denkins, that works out to about two servings of cold-water fish--species like halibut, herring, mackerel or salmon--per week.

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