[wet]

Alpha-linolenic acid, the primary dietary source of omega−3 fatty acids in the diet, is frequently found in green leaves. The leaves and seeds of the perilla plant (widely eaten in Japan, Korea and India) are the richest plant source of alpha-linolenic acid, although linseed oil is also a rich source. Fish oil contains very little alpha-linolenic acid, but is rich in the omega−3 derivatives EPA and DHA. Fish are at the top of a food chain based on phytoplankton (algae) that manufacture large amounts of EPA and DHA.

It has been estimated that thousands of years ago the diet of human hunter-gatherers consisted of approximately equal parts of omega−3 and omega−6 essential fatty acids [*15]. Since the beginning of agriculture ten thousand years ago there has been a steady increase in omega−6 at the expense of omega−3 fat in the human diet. This process accelerated about 50 years ago as cattle began to be fed increasingly on grains rather than grass. Recommendations by nutritionists to eat margarine rather than butter (polyunsaturated rather than saturated fats) increased the trend toward omega−6 and trans fat consumption. Currently, the ratio of omega−6 to omega−3 fatty acids in the American diet is 7−to−1 or more. There are good reasons to believe that this imbalanced essential fatty acid ratio has led to increased cancer, heart disease, allergies, diabetes and other afflictions. Much of the reason for this lies in the membranes of our cells.