If you eat fish every day just to prevent heart attacks, you're eating it for the wrong reason. Studies in Greenland, Japan, the Netherlands, Sweden and the United States show that eating fish helps to prevent heart attacks, while those in Norway, Hawaii and the United States show no protection. Eating fish more often than that offers no additional protection.
Fish can help to prevent heart attacks in middle aged men and older men and women.
There are two components to a heart attack. Over many years, fatty plaques are laid down in arteries and slow blood to a trickle. Then a clot forms, blocking the flow of blood to the heart completely. The heart muscle, unable to get any oxygen, dies and a person suffers a heart attack. Deep water fish contain omega-3 polyunsaturated fatty acids which help to prevent heart attacks by preventing clotting and you get the maximum anticlotting effect from eating fish twice a week.