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Eating fish slows the progression of heart disease!

We have known for a long time that eating fish is good for you. Eating fatty fish like tuna and salmon has been shown to reduce the risk of sudden death. There has not been research, however, to show what effect eating fish might have on the progression of the narrowing of arteries that feed blood to the heart. It is the reduction in size of these blood vessels (the coronary arteries) with plaque that doctors call atherosclerosis.

Worsening atherosclerosis leads to the blockage of blood flow and oxygen to heart muscle. It is the lack of oxygen that causes heart attacks and researchers are very interested in what might slow, stop or reverse the progression of this process. There has been excellent research to show that diet, exercise and stress reduction can actually reverse atherosclerotic plaques in the coronary arteries. A group of researchers offers some insight into the effect that eating fish has on the worsening of heart disease in a study published in the American Journal of Clinical Nutrition (2004; 80: 626 – 632).

The researchers studied 229 women with known heart disease. They started by looking at the study participant’s arteries using cardiac catheterization and measuring the degree of blockages from atherosclerotic plaque. The subjects then filled out a questionnaire about their diet. The primary question was whether they ate ≥ 2 servings of fish per week or ≥ 1 serving of tuna or dark fish. (Dark fish include salmon, mackerel, bluefish, sardines and swordfish.)

They also looked at whether the participants were diabetic and then adjustments were made to account for age, other risk factors for heart disease as well as intake of other fats, cholesterol fiber and alcohol.

About three years later they repeated the cardiac catheterization to look at the diameter of the arteries, the percentage of blockage and if any new blockages had developed. The results showed significantly less narrowing of the arteries in the group that ate 2 or more servings of fish per week.

The investigators also looked at the change in arteries according to which type of fish was consumed. When compared to other fish those who ate tuna and dark fish once or more per week had significantly less narrowing. These changes were greater in women with diabetes who consumed tuna and dark fish more than once a week than for those eating it less often. The frequency of eating tuna did not have as significant an effect in non-diabetic women. The results were similar when the investigators looked at whether any new blockages occurred in the three year period.

This is a great piece of research that shows significant slowing of atherosclerosis in postmenopausal women (especially diabetic women) who ate any fish 2 or more times per week. If the fish consumed was tuna or dark fish, slowing of heart disease was associated with a single serving per week. These effects were similar in non-diabetic women but less so and not felt to be statistically significant.

Fish is good, fish is good for you, fish can slow heart disease, eat more fish!