Fish oil isn't just good for your heart. New evidence suggests it may be good for your waistline, too.
A new study from Japan found that fish oil transformed fat-storage cells into fat-burning cells — potentially preventing fat accumulation and weight gain in middle age. So far, this research has only been conducted in mice.
The authors explained that fish oil activates receptors in the digestive tract and nervous system, which encourage fat-storage cells to metabolize fat.
"People have long said that food from Japan and the Mediterranean contributes to longevity, but why these cuisines are beneficial was up for debate," said lead study author Teruo Kawada, PhD, a professor of agriculture at Kyoto University in Japan, in a press release. "Now we have better insight into why that may be."
In the body, not all fat tissues store fat. "White" cells store fat to maintain energy. "Brown" cells metabolize fat to maintain body temperature. These fat-burning brown cells decrease in number as people age.
A third type of fat cell — "beige" cells — has recently been found in humans and mice. These cells also burn fat and reduce in number as people age. For this study, Dr. Kawada and team looked at whether the number of beige cells in the body could be increased by eating certain types of foods.
"We knew from previous research that fish oil has tremendous health benefits, including the prevention of fat accumulation," Dr. Kawada said. "We tested whether fish oil and an increase in beige cells could be related."
These researchers fed mice either fatty food or fatty food with added fish oil.
The mice in the fish oil group gained between 5 and 10 percent less weight and accumulated between 15 and 25 percent less fat than the mice in the other group.
Dr. Kawada and team also found that some white cells transformed into beige cells in the mice that ate fish oil. In other words, some fat-storage cells acquired the ability to metabolize fat in these mice.
This study was published Dec. 17 in the journal Scientific Reports. No funding sources or conflicts of interest were disclosed.