The institute recommended that adult men eat 17 grams (0.6 ounces) of the omega-6 fatty acid linoleic acid daily and adult women 12 grams (0.42 ounces), while they should eat 1.6 grams (0.06 ounces) and 1.1 grams (0.04 ounces) of the omega-3 fatty acid alpha-linolenic acid, respectively. The amounts vary for children and juveniles, and for those over age 50.

The American Heart Association recommends at least two servings each week of omega-3-rich fatty fish. A serving should be 3 ounces cooked, about the size of a deck of cards. In one study, senior citizens who ate one serving weekly had a 44 percent lower risk of heart attack, according to the organization.

Special fish diets using additives, such as CLA, and grains, such as soybeans, can be formulated to produce designer fish that are high in beneficial fatty acids, Brown said. The research team is studying different fish species to chronicle their development on specialized diets and determine how much of the nutrients they retain.

Purdue scientists discovered that some fish stay lean while others become much fatter because they retain the lipids, or polyunsaturated fat, from the fatty acids. Two fish models they study have very different activity and metabolism levels, and differ in the amount of fat they retain. Eating a high fatty acid diet in a farm environment turns hybrid striped bass into little butterballs, while yellow perch stay very lean, Brown said.

The ability to raise more nutritional fish of a variety of species should encourage growth of the aquaculture (fish farm) industry, he said. But fish are the last major food item still obtained primarily from the wild.

"The wild fish supply just isn't sufficient to provide us with the amount necessary for human consumption," Brown said. "That was decided in 1989 when we hit maximum sustainable yield from the world's oceans, yet the world popu
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Contact: Susan A. Steeves
ssteeves@aes.purdue.edu
765-496-7481
Purdue University
30-Dec-2002