STEVE INSKEEP, HOST:
Several servings of fish per-week are supposed to help your heart and brain. People who don't eat enough fish try fish oil or omega-3 supplements instead. NPR's Allison Aubrey asked if that really helps.
ALLISON AUBREY, BYLINE: Fish is still a big business here at this rustic, open-air fish market along the Potomac River in Washington, D.C.
PATRICK DONAHOE: Got nice fresh Chesapeake Bay rockfish, fresh red snapper. Fresh as it can be.
AUBREY: That's fish monger Patrick Donahoe (ph). As he ices down the daily catch, that distinctive fish market smell fills the air. No place as smelly as a fish market, huh?
DONAHOE: You got that right. Smells like money to me.
AUBREY: For Patrick Reilly (ph), who's shopping here, all of this fishiness is part of the appeal. He associates the smell of the ocean with good health. In fact, he grew up hearing that fish is brain food. And he says eating it makes him feel good.
PATRICK REILLY: Gives me energy (laughter).
AUBREY: Turns out there's likely some truth to this. Inside these fish fillets is a particular type of fat - omega-3 fatty acids that can potentially do our bodies and our brains some good. Here's NIH researcher Joe Hibbeln.
JOE HIBBELN: What's so interesting is that our brains are made of fat, and those fats come right from our diet. We think these omega-3's are important because they reduce inflammation and help neurons function well.
AUBREY: Hibbeln says studies have shown that people who eat fish regularly over a lifetime have a lower risk of heart disease. And some studies suggest a lower risk of cognitive decline. Now, given this connection, there was a hope that, perhaps, giving people fish oil supplements later in life could stave off memory loss. But turns out it's not that simple. A new study published in the Journal of the American Medical Association finds omega-3 supplements given to people in their mid-seventies were no better than a placebo in protecting brain health.
HIBBELN: What this study found was that these omega-3's did not prevent people from getting cognitive impairment.
AUBREY: Hibbeln says perhaps this was just too little, too late.
HIBBELN: It may be that at age 73, it's already too late to change your diet and change your risk of cognitive decline.
AUBREY: Now, it may also be the case that taking a supplement is not the best way to get your omega-3's. In an ideal world, researcher Elizabeth Johnson of Tufts University says, you should aim to eat fish as part of a healthy diet.
ELIZABETH JOHNSON: If you want to get more omega-3 fatty acids in your diet, the best is to get it through food.
AUBREY: Johnson says there's no one magic bullet for protecting brain or heart health.
JOHNSON: These nutrients don't work in isolation, they work together.
AUBREY: So eating a meal of say, salmon, some leafy greens and whole grains?
JOHNSON: You'll be getting not only those omega-3's, but other nutrients that could be of importance.
AUBREY: And all of them together may have a synergistic effect in promoting good health. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.