The Importance Of Omega-3 Fatty Acids

The body can?t easily manufacture omega-3?s like EPA and DHA - they are best supplied by our food. Luckily, the one organism that can make them - plankton - is eaten by certain types of fish (which are in turn, eaten by other fish). We can eat these fish and so get the omega-3 the plankton made originally. Alternatively supplements can be used, which contain the EPA and DHA found in these oil-rich fish. Fish are generally to be preferred over supplements, since they supply other important nutrients like vitamins and minerals also. However, some people are not able or willing to eat fish, and for them supplements, or fish oil supplemented foods, are a feasible and sensible way to get omega-3.

If you are a vegetarian, you can get one of the Omega-3 fatty acids (alpha-linolenic acid or ALA) from sources such as linseed oil or rapeseed oil, though to be most useful to body, the ALA must first be converted to EPA and/or DHA. Modern diets make this conversion process inefficient, so that lots of ALA must be eaten to produce levels of EPA and DHA comparable to those that can be obtained by eating fish.

Fish and seafoods from cold waters characteristically and uniquely contain significant quantities of long chain omega-3 polyunsaturates. Though there is some evidence that fish can elongate and desaturate the shorter chain omega-3 polyunsaturates, current opinion is that most of the long chain omega-3 polyunsaturates are formed in the microscopic algae, plankton and planktonic crustacea at the bottom of the marine food chain. They are then passed up the food chain into the higher fish, and of course ultimately to humans.

The fats in fish are low in saturated fatty acids and contain a type of polyunsaturated fatty acid ('omega'-3) that has been associated with a decreased risk of heart disease in certain people. Remember that the total fat in the diet should be consumed at a moderate level - that is, no more than 30 percent of calories. Mono- and polyunsaturated fat sources should replace saturated fats within this limit.

Great progress has been made over the past 30 years in identifying cardiovascular risk factors and in developing and implementing measures to correct them. The guidelines developed by the Adult Treatment Panel (ATP) of the National Cholesterol Education Program identified low density lipoprotein (LDL) as the major atherogenic lipoprotein and high levels of LDL cholesterol as the primary target for cholesterol-lowering therapy.

The low incidence of cardiovascular disease in Greenland Eskimos appears to be due to their high intake of seal, whale and fish. The lipids of these marine animals lower serum triglyceride and cholesterol levels and help to prevent blood clotting. The latter effect has been related to a change in the balance of prostacyclin and thromboxane as a result of replacing n-6 polyunsaturated fatty acids in the body by n-3 polyunsaturated fatty acids present in marine lipids. Dietary fish oils have also been shown to inhibit development of mammary, pancreatic, intestinal and prostatic tumors in experimental animals. This effect may likewise be due to changes in the production of prostaglandins or related compounds. The involvement of prostaglandins and leukotrienes in immune responses has led to studies on the effects of fish oil on various chronic diseases associated with abnormalities of the immune system. Some of these diseases, such as multiple sclerosis and psoriasis, are also relatively uncommon in Eskimos. Preliminary results of these studies are encouraging, but more work is required to assess the usefulness of dietary fish oils in treatment of these diseases. In addition to their apparent therapeutic value, n-3 fatty acids are considered essential dietary components since they cannot be synthesized in the body and appear necessary for normal vision and probably other body functions.

From population studies, diets high in fish are associated with reduced CHD risk. Fish oils and omega-3 fatty acids result in decreased triglycerides, and may increase LDL-Cholesterol and/or apolipoprotein B level(s). They also impair clotting and diabetic control. Omega-3 fatty acids, in large amounts, may reduce excessive triglyceride levels that do not respond adequately to recommended dietary therapy.

Published clinical research, as well as various theoretical considerations, suggest that supplemental intakes of the 'metavitamins' taurine, coenzyme Q10, and L-carnitine, as well as of the minerals magnesium, potassium, and chromium, may be of therapeutic benefit in congestive heart failure. High intakes of fish oil may likewise be beneficial in this syndrome. Fish oil may decrease cardiac afterload by an antivasopressor action and by reducing blood viscosity, may reduce arrhythmic risk despite supporting the heart's beta-adrenergic responsiveness, may decrease fibrotic cardiac remodeling by impeding the action of angiotensin II and, in patients with coronary disease, may reduce the risk of atherothrombotic ischemic complications. Since the measures recommended here are nutritional and carry little if any toxic risk, there is no reason why their joint application should not be studied as a comprehensive nutritional therapy for congestive heart failure.

Other studies have indicated that omega-3 fatty acids may be effective in treating mood disorders.

For example, one investigator has shown a correlation between the prevalence of major depression and the amount of fish consumed per capita worldwide. Others have found decreased amounts of EPA (one of the active ingredients in omega-3 fatty acids) in the red blood cells of patients with major depression. And a recent small study of patients with bipolar illness indicated that omega-3 fatty acids prevented relapses, especially of depression, in patients.

This journal article describes a study of the potential mood-stabilizing properties of omega 3 fatty acids in bipolar (manic-depressive) disorder. Thirty patients with bipolar disorder, aged 18 to 65 years, participated in this placebo-controlled, double-blind trial. The patients were randomly assigned to receive omega 3 fatty acids (9.6 g/d) or placebo (olive oil), in addition to their regular treatment, for 4 months. Randomization was stratified according to sex, the presence or absence of concurrent lithium treatment, and the presence or absence of rapid cycling. A Kaplan-Meier survival analysis showed that the omega 3 fatty acid group had a significantly longer period of remission than the placebo group. The omega 3 fatty acid group also performed better than the placebo group on nearly every other outcome measure. Treatment was generally well tolerated. The authors conclude that the addition of omega 3 fatty acids appears to have improved the short-term course of illness in this group of patients with bipolar disorder.

The old wives adage that fish is brain food received a substantial boost when the results of a research project were announced. The study looked at the possible value of fish oil in the treatment of hospitalised manic-depressives. These patients are severely affected, and suffer violent mood swings which range from suicidal depression, to raging mania. 30 such patients were involved in the trial, half given fish oil, and half a placebo. Fish oil has in the previous studies shown suggestions that it might be useful in the treatment of mental disorders. The double blind study, carried out by Dr Andrew Stoll and colleagues at the McLean Hospital in Belmont, Massachusetts, was planned to last 4 months, but was brought to a premature conclusion, because the benefits of the fish oil treatment were so marked, that it was considered unethical to continue to deny the same benefits to the patients taking the placebo treatment. The study was published in the May 1999 issue of the journal Archives of General Psychiatry. Severe bipolar disorder, as the condition is known medically, affects around 1% of the population, and around 10-15% of those affected die from suicide. The prevalence of the condition has increased 100 fold in the past 100 years, but the condition is rare in fish-eating countries such as Japan, Korea, Malaysia and Taiwan. Current drug therapy is not well accepted by patients in contrast to the fish oil treatment used in this study.

The value of fish oil in such treatments is thought to be due to it?s unique content of long chain omega-3 polyunsaturates, and in particular one called docosahexaenoic acid, or DHA. The brain is unique in having a high concentration of DHA. It is thought that modern diets and lifestyles put at risk the body?s ability to maintain brain DHA level, and that when the level falls, mental problems become more prevalent. Interestingly, in the 18th century, one treatment recommended for "melancholia" was to eat cow brain. Like the human brain and in fact most mammals, cow brain also contains a relatively high concentration of DHA!

Studies with hospitalised schizophrenics and children suffering from attention deficit-hyperactivity disorder (ADHD) have also shown that the long chain omega-3 polyunsaturates in fish oil can have a beneficial impact on brain function.

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  • Triglyceride, High Density Lipoprotein, and Coronary Heart Disease. NIH Consens Statement 1992 Feb 26-28;10(2):1-28.
  • Biological effects of fish oils in relation to chronic diseases. Lipids (UNITED STATES) Dec 1986, 21 (12) p731-2
  • Fish oil and other nutritional adjuvants for treatment of congestive heart failure. Medical Hypotheses (United Kingdom), 1996, 46/4 (400-406)
  • Stoll, A.L.; et al. Omega 3 Fatty Acids in Bipolar Disorder: A Preliminary Double-Blind, Placebo-Controlled Trial. Archives of General Psychiatry. 56: 407-412. May 1999.

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