Essential fatty acids in health and chronic disease
Human beings evolved consuming a diet that contained about equal amounts of
n-3 and n-6 essential fatty acids. Over the past 100.150 y there has been an
enormous increase in the consumption of n-6 fatty acids due to the increased
intake of vegetable oils from corn, sunflower seeds, safflower seeds,
cottonseed, and soybeans. Today, in Western diets, the ratio of n-6 to n-3
fatty acids ranges from 20.30:1 instead of the traditional range of 1.2:1.
Studies indicate that a high intake of n-6 fatty acids shifts the
physiologic state to one that is prothrombotic and proaggregatory,
characterized by increases in blood viscosity, vasospasm, and
vasoconstriction and decreases in bleeding time. n-3 Fatty acids, however,
have antiinflammatory, antithrombotic, antiarrhythmic, hypolipidemic, and
vasodilatory properties. These beneficial effects of n-3 fatty acids have
been shown in the secondary prevention of coronary heart disease,
hypertension, type 2 diabetes, and, in some patients with renal disease,
rheumatoid arthritis, ulcerative colitis, Crohn disease, and chronic
obstructive pulmonary disease. Most of the studies were carried out with
fish oils [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)].
However, -linolenic acid , found in green leafy vegetables, flaxseed,
rapeseed, and walnuts, desaturates and elongates in the human body to EPA
and DHA and by itself may have beneficial effects in health and in the
control of chronic diseases.