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(NBC) - Millions of Americans choke down large fish oil supplements every day, coughing up more than $1-billiona year, based on the belief that the pills can help prevent heart disease.

Now a large review of research shows no overall heart benefit to taking Omega-3 fatty acid, or fish oil supplements.

There was a small reduced risk for heart-related deaths, but researchers say it wasn't significant.

Other forms of heart disease prevention have been well documented.

"Eating healthfully, exercising is really so much more important than supplement," says Elisabetta Politi, a registered dietitian with the Duke Diet and Fitness center.

According to the Council for Responsible Nutrition nearly a quarter of all U.S. adults take fish oil pills.

In a statement, the organization suggested the research results were skewed because the "combined studies were not comparable in their design."

This is the latest in a string of studies finding little to no benefit to supplements.

Recent studies have refuted claims that Ginkgo Biloba can prevent dementia and that Vitamin D may lower cholesterol.

Dietitians say it's the synergy of phyto-chemicals and multiple nutrients in food that makes healthy food healthy.

"It's not the same to get vitamins and supplements from a pill," Politi explains. "It's so much better to get it from food."

Omega-3 fatty acids are found naturally in oily fish like salmon and tuna, flax seed and walnuts.

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