Really? Fish Oil Doesn't Help Prevent Heart Attacks?

A large-scale study conducted in Italy found that eating fish is good for your heart but taking fish oil capsules does not prevent heart problems in people who are already taking heart medications, recent headlines said.

The study in question, conducted by the Mario Negri Institute for Pharmacological Research in Milan, involving 860 doctors in general practice who tracked the heart health of 12,153 people who took either a single fish oil capsule or a placebo (actually a capsule of olive oil) every day for five years. Volunteers in this group were already taking Aspirin, high blood pressure medications, or statins to lower cholesterol because they had been deemed to be at high risk for heart attack or stroke due to smoking, diabetes, obesity, or family history of cardiovascular disease. 

The purpose of the study was to measure whether taking a small amount of fish oil would be a useful addition to aggressive medical treatment to prevent cardiovascular catastrophes. Since this study involved patients who had not previously had a heart attack or stroke, deaths from cardiovascular disease would be interpreted as arising from undetected heart or vascular disease in people who otherwise were known to be a high risk.

Indications from the study were that fish oil did not add to the benefits of aggressive medical treatment. During the five years of the study, 12% of participants taking fish oil daily as well as 12% of participants taking the placebo suffered heart attack, stroke, or death due to cardiovascular causes. (Actually, a slightly greater number of study participants taking fish oil suffered a cardiovascular catastrophe during the five years of the study, 11.9% of fish oil users compared to 11.7% of those who took the placebo.)

The overall rate of heart attack, stroke, or death at the end of the first year of the study was lower than the study investigators anticipated. In Italy, fish oil is routinely prescribed to patients who have already had a heart attack, and the cost of the fish oil covered by medical insurance, but fish oil had not been given on a routine basis to high-risk patients who had not yet had heart attack or stroke.

Does This Risk And Prevention Study Mean That Fish Oil Does Not Prevent Heart Disease?

The recent Italian study was not the first time a clinical trial of the use of fish oil had found that it failed to provide protection against cardiovascular illness. A study published in 2010 found that taking fish oil did not protect against a condition known as atrial fibrillation in people who had already had a heart attack. However, what the headlines concerning this study overlook is that users of fish oil experienced lower than expected rates of heart attack, stroke, and sudden death, they simply did not get better results than people who took the placebo capsule, which in this study was a capsule of olive oil.

Another way of looking at these results is that fish oil and olive oil may be equally beneficial. And no fewer than 39 studies have found that olive oil protects against various manifestations of cardiovascular illness.

What do scientists believe olive oil can do for you?

• A study sponsored by the US Environmental Protection Agency implies that adding just a small amount of olive oil to the diet, 3 grams (about a tablespoon) per day to be precise, can protect against the cardiovascular effects of dust and fine particulate matter in the air. Air pollution, many would be surprised to learn can cause irregular heartbeat, high blood pressure, and even high cholesterol.
• Scientists at the Universidad de Zaragoza in Spain confirm that consuming oil olive increases heart-protective HDL cholesterol.
• A group of researchers sponsored by the University of Tsukuba in Japan report that a compound in olive oil and olive leaf extract called hydroxytyrosol helps  blood vessels dilate through a biochemical process similar to the process triggered by taking a nitroglycerin pill or nitroglycerin spray, without their unpleasant side effects (usually a headache later).
• Laboratory studies with animals at the University of Siena in Italy have found that adding olive oil to their diets decreases platelet aggregation, making red blood cells less “sticky” and less likely to form clots, and reduces the production of inflammation-causing homocysteine.
• Scientists at the Universidad Complutense de Madrid found that adding a combination of olive oil and sunflower oil to the diets of post-menopausal women lowered LDL (“bad”) cholesterol and reduced the risk of heart attack and stroke.
• And a remarkable finding in many of these studies was that the greatest benefits were obtained from the less expensive refined olive oil, rather than the more expensive virgin olive oil, although both kinds of olive oil are heart-healthy.

What the widely reported study on fish oil probably found was that olive oil was as protective as fish oil, not that fish oil is not beneficial for heart protection. It is still a good idea to take fish oil for fighting inflammation in other organs, but olive oil may be equally as helpful for the heart.