Omega-3 Fatty Acids Help Control Weight

Marine omega-3 polyunsaturated fatty acids (PUFAs) may help reduce accumulation of body fat by promoting fat burning and reducing the number of cells in adipose tissue, according to a study published in the December 2004 issue of Lipids.

Researchers tested the effects of Omega-3 fatty acids -- eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) -- sourced from fish oil on mice and found weight gain induced by a composite high-fat diet was limited when the animals' EPA and DHA intake was increased from 1 percent to 12 percent of total dietary lipids. Accumulation of adipose tissue -- particularly in the abdominal region -- was reduced in the animals, and changes in plasma markers and adipose gene expression indicated EPA and DHA improved lipid and glucose metabolism. The scientists concluded EPA and DHA have an antiadipogenic effect and reduce accumulation of body fat by limiting both hypertrophy and hyperplasia of fat cells.

"It is well established that a diet rich in seafood prevents weight gain, but the mechanisms responsible for this effect have not been known," said Morten Bryhn, M.D., Ph.D., director of research and development for Lysaker, Norway-based Pronova Biocare, makers of EPAX® Omega-3 EPA/DHA concentrates.

In a release, Pronova commented that the study clearly demonstrated EPA and DHA increase oxidation of fat by activating genes that break down fat in the mitochondria and peroxisomes, promoting weight loss as well as preventing weight gain in animals given free access to food. In addition, the EPA and DHA not only intensified breakdown of fat but reduced the number of fat cells, particularly in the abdominal region, the company said.

"Being overweight is not only a problem of too much food and too little exercise, but also a problem of bombarding genes with signals leading to fat accumulation," Dr. Bryhn said. "A diet rich in red meat and vegetable oils increases accumulation of fat in fat tissue because of a chronic disarray of genes responsible for handling fatty acids and carbohydrates. The number of fat cells increases, and turnover of carbohydrates into fat is facilitated. The net result is being overweight, which leads to obesity that is difficult to curb by calorie reduction and exercise only. Genes are constantly programmed to a situation of starvation and they need to be reprogrammed. Omega-3 fatty acids from seafood seem to do exactly that."

However, Dr. Bryhn cautioned since the process of reprogramming genes is slow, supplementation with marine omega-3 PUFAs will not produce immediately drastic effects on weight. "Weight control should be a combination of reduced intake of red meat, saturated fat and foods containing vegetable oils and carbohydrates; regular exercise; and increased intake of omega-3 fatty acids high in DHA," he said.

Source:

Ruzickova J, Rossmeisl M, Prazak T, Flachs P, Sponarova J, Veck M, Tvrzicka E, Bryhn M, Kopecky J: Omega-3 PUFA of marine origin limit diet-induced obesity in mice by reducing cellularity of adipose tissue. Lipids 2004, 39:1177-1185.

Key concepts: omega-3 fatty acids, fish oil, EPA, DHA, weight loss