Fish oil turns fat-storage cells into fat-burning cells in mice, study finds

Photo: Neil Tackaberry/Flickr

Fish oil has long been known to confer a wide range of health benefits, including boosting the cardiovascular system and potentially even treating the effects of schizophrenia. Now a new study from Japan says it could also help people trying to lose weight.

Researchers from Kyoto University found that mice fed on fatty food and fish oil gained considerably less weight and fat than mice that consumed fatty food alone. The findings suggest that fish oil is able to transform fat-storage cells into fat-burning cells – and if the same process occurs in humans, fish oil could help us reduce weight gain, especially as we age, when our fat-burning cells are in lesser supply.

While we might think of our fat tissue as primarily a fat storage system, this isn’t always so. White fat cells store fat, but brown fat cells metabolise fat to maintain a stable body temperature. Our bodies metabolise fat more easily when we’re young, as we have a greater amount of brown fat cells in youth, but we start to lose them in maturity.

Scientists have also discovered a third type of fat cell – beige fat cells – which function much like brown fat cells in mice and people. Also like brown fat cells, the beige cells diminish in number as we get older, making it harder for our bodies to burn fat. This is where fish oil could come into play.

“We knew from previous research that fish oil has tremendous health benefits, including the prevention of fat accumulation,” said food scientist Teruo Kawada from Kyoto University. “We tested whether fish oil and an increase in beige cells could be related.”

To examine the links, the researchers fed one group of mice fatty food, and another group fatty food with fish oil additives. The results, published in Scientific Reports, reveal how the animals that consumed the food with fish oil gained less 5 to 10 percent less weight and 15 to 25 percent less fat – a significant reduction in the circumstances.

But why does this happen? The researchers say that fish oil activates receptors in the digestive tract, which fires up the sympathetic nervous system and induces storage cells to metabolise fat. In other words, the fish oil causes white cells to transform into beige cells, effectively turning fat-storage tissue into fat-metabolising tissue and leading to increased energy expenditure at the expense of weight gain and fat accumulation. This is good to know.

It’s too soon to say whether these findings also apply to humans, but further studies may show just that, which the researchers believe could contribute to an effective treatment for obesity.

“People have long said that food from Japan and the Mediterranean contribute to longevity, but why these cuisines are beneficial was up for debate,” said Kawada. “Now we have better insight into why that may be.”

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