Kyoto University researchers have found that fish oil transforms fat-storage cells into fat-burning cells which help alleviate middle age spread.
The team explains in Scientific Reports that fish oil activates receptors in the digestive tract, fires the sympathetic nervous system, and induces fat storage cells to metabolize fat.
Fat tissues don't all store fat. White fat cells store fat in order to maintain energy supply, while brown fat cells metabolize fat to maintain a stable body temperature. Brown fat cells are abundant in babies but decrease in number as they mature into adults.
A third type of fat cell -- called beige cells -- has recently been found in humans and mice, and has been shown to function much like brown cells. Beige cells decrease in number as people approach mid-age; without the fat-metabolizing beige cells, fat keeps accumulating for decades without ever being used.
Kawada and his team investigated whether these beige fat cells could be increased by taking in certain types of foods.
"We knew from previous research that fish oil has tremendous benefits on health, including the prevention of fat accumulation," says senior author Teruo Kawada. "We tested whether fish oil and increase in beige cells could be related."
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% less weight and 15-25% less fat compared to those that did not consume fish 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 fat.
"People have said that food from Japan and the Mediterranian regions contributes to longevity, but why it was good was up for debate," said Kawada. "Now we have better insight into why that is."
Kyoto University shows how fish oil improves fat metabolism
Kim M, Goto T, Yu R, Uchida K, Tominaga M, Kano Y, Takahashi N and Kawada T.
"Fish oil intake induces UCP1 upregulation in brown and white adipose tissue via the sympathetic nervous system "
Scientific Reports 12/17