Fat in your diet is essential!
Some of the food sources of fatty acids are fish and shellfish, flaxseed (linseed), soya oil, canola (rapeseed) oil, hemp oil, chia seeds, pumpkin seeds, sunflower seeds, leafy vegetables, and walnuts.
Essential fatty acids play a part in many metabolic processes, and there is evidence to suggest that low levels of essential fatty acids, or the wrong balance of types among the essential fatty acids, may be a precursor in a number of illnesses.
Plant sources of omega-3 do not contain eicosapentaenoic acid and docosahexaenoic acid. This is thought to be the reason that absoption of essential fatty acids is much greater from animal rather than plant sources.
EFA content of vegetable sources varies with cultivation conditions. Animal sources vary widely, both with the animal’s feed and that the EFA makeup varies markedly with fats from different body parts.
The primary source of omega6 fatty acids in the diet is linoleic acid from the oils of seeds and grains. Sunflower, safflower and corn oil are particularly rich sources of linoleic acid, which is at the root of the omega6 fatty-acid family. Evening primrose oil and borage oil are high not only in linoleic acid, but the omega6 derivative gamma-linolenic acid (GLA). Avocado is 15-20% oil (mainly monosaturated), but also high in linoleic acid. (Avocado has the highest fat content and the highest fiber content of any fruit.)
Alpha-linolenic acid, the primary dietary source of omega3 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 omega3 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. Nonetheless, fish can be high in toxic mercury.
It has been suggested that thousands of years ago the diet of human hunter-gatherers consisted of approximately equal parts of omega3 and omega6 essential fatty acids. However, Since the beginning of agriculture ten thousand years ago there has been a steady increase in omega6 at the expense of omega3 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 omega6 and trans fat consumption. Currently, the ratio of omega6 to omega3 fatty acids in the American diet is 7to1 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.
The low death rate from coronary heart disease among Greenland Eskimos led scientists to suspect that high fish consumption might be protective. A 20-year study of 852 middle-age Dutch men showed that coronary artery disease was more than 50% lower among the men who consumed at least 30 grams of fish per week, when compared with men who did not eat fish. A 30-year study of over 2,100 Chicago men showed a 62% risk of coronary heart disease and 56% risk of sudden myocardial infarction for men who ate at least 35 grams of fish daily, compared to those who ate none.
Fish oil has been shown to lower LDL-cholesterol by about 13%, to lower blood pressure, and to dramatically lower blood triglycerides. The effect on triglycerides, in particular, appears to be due to EPA and DHA, because flaxseed (ie, linseed oil, which is over 50% alpha-linolenic acid) did not lower triglycerides. More careful analysis has established that DHA alone has no effect on blood triglycerides, but that EPA alone is capable of lowering blood triglycerides by about 30%.
Although most fish oils are high in EPA and DHA, there are some fish oils which are not. Flounder, swordfish and sole are particularly low in EPA and DHA. Fish oils having the highest levels of EPA and DHA include mackerel, herring and salmon. Some fish, such as cod and haddock, store most of their fat in the liver, therefore the liver oils of these fish should be taken rather than the fillet.
Optimum dietary benefit from fat for most people would come from a program of reduced total fat, reduced saturated and unessential fat, and increased proportions of omega3 (relative to omega6) essential fats. A high omega3 oil like perilla oil might be a simple remedy for young people, and the best remedy for smokers. But as most people age, they will benefit most from CLA, GLA, and DHA supplementation combined with antioxidants (especially vitamin E) to protect these polyunsaturated essential fats from oxidation.
Fats are an important component of membranes in our hearts, brains, immune cells and most of the other tissues of our bodies. Since we need these fats, it is important to ensure that we have the right kind of fats, that we have enough of them and that we protect them with antioxidants.