On a regular basis, we read about the benefits of eating fish and consuming omega-3 fatty acids. We have been told that there is epidemiologic data showing the beneficial effects a diet rich in fish oils can have on cardiovascular disease.
Recently, the Canadian Medical Association Journal (CMAJ) published several articles on this subject. The main theme of the articles was to see if there is a scientific evidence to show fish oils are beneficial for patients with heart disease and if fish oils prevent any kind of chronic disease.
Reports suggest that an average typical Western diet has omega-3 fatty acids found in fish to be about 150 mg per day. This is equivalent to eating about one fish meal every 10 days. This is not enough. The general recommendation is 650 mg per day of omega-3 fatty acids..
The American Heart Association recommends that people without coronary heart disease have two fish meals each week (at least 300 mg of omega-3 fatty acids daily), and they recommend that patients with documented coronary heart disease receive 1000 mg daily.
Omega-3 fatty acids are DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These are considered essential fatty acids as our body does not make them and we have to obtain them from food or commercially marketed pills.
There are three sources of omega-3 fatty acids: the most important source is fish (e.g. salmon, tuna, and trout) which has long chain fatty acids DHA and EPA. Some foods like eggs, dairy products and yogurt are fortified with omega-3 fatty acids. Second source is plants (which has short chain fatty acid alpha-linolenic acid)and plant oils, including leafy vegetables, walnuts, mustard seed oil, soy bean oil, canola oil and flaxseed oil (which is made up of 50 per cent alpha-linolenic acid). The third source is commercially available salmon and flax seed oil pills. Fish oil capsule 1000 mg has 300 to 600 mg of DHA and EPA.
It is important to remember that plant omega-3 fatty acids are not the same as fish omega-3 fatty acids. Chemically they are similar but they are metabolized in the body differently. Our bodies can convert about five per cent of -linolenic acid to EPA.
How do omega-3 fatty acids help us?
DHA and EPA are thought to confer their cardiac protective effects by making the blood less likely to form clots, lowering triglycerides (fat in the blood) and protecting against irregular heartbeats that can cause sudden cardiac death. However, the results of all studies have not been consistent. Besides, we don’t know as much about the effects of plant omega-3 fatty acids, but they appear to have similar actions in reducing coronary heart disease events, says one of the articles in the CMAJ.
Medical literature suggests omega-3 fatty acids from fish may reduce cardiac deaths, inflammatory disease, including rheumatoid arthritis and ulcerative colitis, and promote brain development and mental function. Generally speaking, there are no risks in taking omeg-3 fatty acids.
A 2006 review of hundreds of studies on fish and health concluded that eating one to two servings each week is enough to reduce the risk of dying from heart attack by 36 per cent.
Should patients with cardiovascular disease take fish oil? An article in the CMAJ by Nair and Connolly says three randomized controlled trials failed to convincingly demonstrate a beneficial effect of omega-3 fatty acids in preventing ventricular arrhythmia (irregular heart rhythm) and cardiovascular death.
Health Canada currently does not approve omega-3 fatty acids for prevention of cardiovascular outcomes, says the article and there is insufficient evidence to recommend the routine use of omega-3 fatty acids. In spite of these conclusions by Nair and Connolly, many experts believe that taking omega-3 fatty acids may lead to a general increase in the overall health and well-being of the population.
Finally, remember omega-3 fatty acids are not panacea for all kinds of health problems. . Regular exercise and healthy eating is important part of staying healthy.
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