Why Eating Fish Might Lower Your Odds of Depression

People who eat a lot of fish may have a lower risk of depression, according to new research.

A review of 26 studies that was published in the Journal of Epidemiology & Community Health showed that men who regularly ate fish had a 20 percent lower risk and fish-eating women had a 16 percent lower risk of depression, compared with those who ate less fish and no fish at all.

“Higher fish consumption may be beneficial in the primary prevention of depression,” researchers concluded in the analysis, which included data from more than 150,000 people in Europe, North America, Asia, Oceania, and South America.

However, Fang Li, one of the co-authors of the review, notes to Yahoo Health that “further studies are required to define how much fish people should eat to reap the benefits.“

Depression is the leading cause of disability for people age 15 to 44 in the U.S., the Anxiety and Depression Association of America reports, and more than 14.8 million American adults are impacted by the disorder.

Previous research has shown a link between eating fish and depression, but the impact varied by gender. A study published in the Journal of Affective Disorders found that women who didn’t eat a lot of fish were more likely to be depressed (but the same wasn’t true for men).

The connection is clearer among those who take fish oil supplements. A large Norwegian study of 22,000 people found that those who took fish oil were about 30 percent less likely to have symptoms of depression than those who didn’t. The longer study participants took fish oil, the less likely they were to experience symptoms of depression.

But what could explain this connection? Even the study’s researchers aren’t sure.

Among their theories, spelled out in the study: The omega-3 fatty acids in fish may alter the structure of the brain’s cell membranes, or the fish’s fatty acids can impact dopamine and serotonin levels, which can lead to lowered rates of depression.

But psychologist Paul Coleman, PsyD, tells Yahoo Health the link may be even simpler. “It could be that people who eat more fish are health conscious and less likely to eat junk food,” he says. “Because they are health-conscious, it means they also take care of themselves in other ways — more exercise, clean living, etc., all of which can reduce the likelihood of depression.”

Coleman also points out that the reverse can be true: People who aren’t depressed may be more likely to eat fish.

Certified dietitian-nutritionist Gina Keatley tells the link could be due to fish’s “zoonutrients,” substances found in animals that are beneficial to human health.

“There are zoonutrients in fish that impact our bodies in ways we don’t yet understand,” she says. “Researchers think it has to do with the omega-3 fatty acids and their impact on our neural structure and function.”

While scientists found that more fish was better for fighting depression, Keatley recommends that you eat at least eight to 12 ounces of fish a week (and avoiding high-mercury versions like shark, swordfish, king mackerel, and tilefish).

That amount may also help lower your cholesterol, as well as your risk of developing heart disease and cancer, she says.

“I’m encouraged by the findings,” Keatley says. “Depression is a difficult issue that impacts millions around the world and … many side effects of treatments are undesirable. A dietary solution would be ideal.”

Scientists noted in the study that additional research is needed to determine why the link between fish consumption and depression exists, as well as which types of fish achieve the best results.