One of the omega-6 fatty acids, arachidonic acid, can be used by the body to make substances that are inflammatory, increase blood clotting, or constrict blood vessels.16, 17 A controlled study showed that a low arachidonic acid diet provided some relief to people with rheumatoid arthritis, an inflammatory disease.18 However, studies of the effect of arachidonic acid on heart disease risk factors have found either no effect or a beneficial effect of higher arachidonic acid intake.19 More research is needed to determine the effects of arachidonic acid on different diseases.
Since arachidonic acid can be made from other omega-6 fatty acids, some authorities have theorized that reducing the consumption of all omega-6 fatty acids might help prevent or relieve inflammatory diseases and other conditions, such as heart disease, that are associated with certain arachidonic acid byproducts.20, 21 However, production of arachidonic acid from other omega-6 fatty acids appears to be quite limited.22 Also, gamma-linolenic acid is an omega-6 fatty acid that the body can use to make anti-inflammatory substances.23, 24 Finally, preliminary studies have found that blood measures of inflammation are actually lower in people with higher omega-6 intake,25, 26 and preliminary and controlled studies suggest that high omega-6 intake prevents cardiovascular disease.27 Overall, there appears to be benefit, not risk, in consuming omega-6 fatty acids other than arachidonic acid.