Fish oil can lower the risk of heart disease in women according to a study released last week by researchers at Brigham and Women’s Hospital and the Harvard School of Public Health.

Coronary heart disease is the leading cause of death in the U.S.—500,000 Americans die from heart disease each year and nearly 7 million suffer from the disease, the study’s statistics show.

“We found that fish oil contains omega 3 fatty acids which can help stabilize the heart beat and reduce the amount of tryglycerides,” said Dr. Frank Hu, head researcher at Brigham and Women’s. These oils can be found in dark, fatty fish such as salmon and mackerel.

The study found that the risk of heart disease was decreased by 31 percent in women who consumed fish two to four times a week.

Even women who only consumed fish once a week experienced a 29 percent decline in their chances of developing heart disease.

The researchers used data collected over the course of sixteen years from tracking 84,688 female nurses involved in the Brigham and Women’s study.

Hu said he decided to conduct the study following many prior studies which provided controversial evidence both for and against the consumption of fish oil.

Hu said recommends that both men and women consume fish two to four times a week to lower the risk of heart disease. Alternative sources also rich in omega 3 fatty acids include nuts and leafy green vegetables, Hu said.

But, while Hu said he would not advise healthy people to take supplements, the study did recommend supplements for people with heart diseases and diabetes.

“Fish oil is only a small part of the picture in reducing heart disease,” Hu said.

Heart disease is caused by many factors such as smoking, high blood pressure, high blood cholesterol, obesity and lack of physical exercise.

Hu said the consumption of fish oil must be accompanied by a comprehensive program includes maintaining healthy body weight, not smoking and eating a healthy diet of fruits, vegetables and fiber.