Fish oil transforms fat-storage cells into fat-burning cells, which may reduce weight gain in middle age, finds a recent study.
The Kyoto University researchers explained that fish oil activates receptors in the digestive tract, fires the sympathetic nervous system, and induces storage cells to metabolize fat.
Fat tissues don't all store fat. So-called "white" cells store fat in order to maintain energy supply, while "brown" cells metabolize fat to maintain a stable body temperature.
Beige cells also reduce in number as people approach middle age; without these metabolizing cells, fat continues accumulating for decades without ever being used.
The scientists investigated whether the number of these beige cells could be increased by taking in certain types of foods. The team fed a group of mice fatty food, and other groups fatty food with fish oil additives.
The mice that ate food with fish oil, they found, gained 5-10 percent less weight and 15-25 percent less fat compared to those that did not consume the oil.
They also found that beige cells formed from white fat cells when the sympathetic nervous system was activated, meaning that certain fat-storage cells acquired the ability to metabolize.
Senior author Teruo Kawada said that people have long said that food from Japan and the Mediterranean contributes to longevity, but why these cuisines are beneficial was up for debate. Now, they have better insight into why that may be. The study appears in Scientific Reports.