Evidence supports a role for dietary fish oils in the prevention of cardiovascular disease. When the fatty acids docosahexaenoic acid (DHA, C22:6 (n-3)) and eicosapentaenoic acid (EPA, C20:5 (n-3)) are included in the diet, they alter several mechanisms that may explain this effect. In particular fish oils are known to reduce elevated levels of the very low density lipoprotein (VLDL) cholesterol. The beneficial effects of fish oils on cardiovascular disease have been well reported in the nutritional literature. For example, in one study1, researchers investigated the ability of n-3 fatty acids from fish oils to protect against the development of coronary heart disease (CHD).In the study, the authors compared DHA consumption with level of coronary artery blockage, in order to find associations between the two parameters. Initial dietary recall techniques did not yield reliable information about fat intake and so the study was conducted by direct measurement of periumbilical adipose tissue, a method that has shown to be a good indicator of dietary intake.
The authors then measured the degree of coronary artery disease as a percentage of stenosis of the lumen of coronary arteries in 40 consecutive autopsies. The subjects were divided into three groups, those with the highest degree of stenosis (n=13), those with the lowest degree of stenosis (n=13) and an intermediate group (n=14). After multiple regression was used to guard against potential confounding effects of body weight and age, it was reported that those in the group with highest degree of stenosis, had the lowest concentration of DHA in their adipose-tissue and the group with the lowest degree of stenosis had the highest concentration of DHA in their adipose tissue. The authors concluded that the study supports the hypothesis that fish oil consumption is associated with a reduced risk of coronary artery disease in humans. The exact mechanisms for these protective effects are not known, but they are unlikely to be explained by lower VLDL plasma levels. Therefore the fish oils could simply be a marker for the intake of a high quality diet, with other dietary variables the possible protective factor.
