Omega-3 Fatty Acids Aid Artery Function

Source: Tufts University
October 11, 2002 (Reviewed: October 19, 2004)

Health-conscious consumers have likely already gotten the message that fish should be part of a heart healthy diet. But exactly how omega-3 fatty acids - the component in fish believed to be responsible for its health benefits - influence the cardiovascular system is still under review.

A recent study takes scientists one small step further in determining how this type of fatty acid may function with regard to heart health. The results are published in the American Journal of Clinical Nutrition.

Measuring arterial blood flow and pressure

Researchers wanted to determine if either of two omega-3 fatty acids, eicosapentanoic acid (EPA) or docosahexanoic acid (DHA), had any effect on systemic arterial compliance (SAC), a measurement of arterial blood flow and blood pressure. Low measures of SAC may be a risk factor for cardiovascular disease.

Thirty-eight men and postmenopausal women aged 40-69 who had abnormal lipid profiles (high cholesterol, high triglycerides, or low HDL cholesterol) were randomly assigned to receive one of three treatments for 7 weeks: EPA supplement, DHA supplement, or a placebo. To keep their intake of omega-3 fatty acids limited to the supplements, the participants were instructed not to eat fish or other dietary sources of omega-3 fatty acids.

In analyzing the data, the researchers controlled for other factors that could influence heart health, such as smoking, alcohol intake, use of hormone replacement therapy, and use of certain medications or dietary supplements.

Both omega-3 fatty acids improve artery function

Participants in both the EPA and DHA groups experienced significant improvements in their SAC measurements after 7 weeks, whereas the participants in the placebo group did not. EPA increased SAC by 36%, and DHA increased SAC by 27%. These increases are thought to reduce cardiovascular disease risk.

Possible pathways

The authors of this study say that multiple factors probably contributed to these findings. SAC measurements can be influenced by endothelial function, tonicity of smooth muscle coat, and the physical properties of the proteoglycans (part of the extracellular matrix of connective tissue). Each factor has an effect on the tone and elasticity of arterial walls, and studies have shown each to be affected by omega-3 supplementation.

Advice to patients

The results of this study are useful to scientists wanting to understand the 'how' and 'why' behind omega-3s, but consumers typically want the 'what,' as in, 'what should I eat?' And, in this case, that means advising them to eat more foods high in omega-3 fatty acids. Some of the best sources of omega-3s are fatty fish like salmon, albacore tuna, mackerel, sardines, and lake trout. Non-fish options include flax seed, canola and soy oils, and walnuts. All are rich in alpha-linolenic acid, which the body converts to EPA and DHA.

What about supplements?

Individuals who aren't fans of fish might be tempted to turn to supplements to boost their intake of omega-3s. But, while the results of this small study are encouraging, it's not yet clear if omega-3 supplements are the way to beat cardiovascular disease. Fish oil capsules can deliver an omega-3 dose much higher than could be consumed in foods. Since omega-3s decrease platelet aggregation and increase clotting time, at high doses supplements could do more harm than good.

Source

• The n-3 fatty acids eicosapentanoic acid and docosahexanoic acid increase systemic arterial compliance in humans. P. Nestel, H. Shige, S. Pomeroy,  et al., Amer J Clin Nutr, 2002, vol. 76, pp. 326--330

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