Is the ratio of omega-6 to omega-3 important and what ratio is best?
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At this time, linoleic (18:2 omega-6) and alpha-linolenic acid (18:3 omega-3) are considered the dietary essential fats. These fats can be used to make a family of hormone-like substances called eicosanoids (thromboxanes, prostaglandins, prostacyclins and leukotrienes) as shown in Eicosanoid Synthesis Figure. In addition, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are omega-3 PUFAs in fish and other sea animals and can substitute for linolenic acid. In fact, EPA is the starting omega-3 fat for derived eicosanoids while omega-6 fats arachiodonic and dihomogamma linolenic acid are used to make the eicosanoids derived from omega-6 fats. |
Many of the eicosanoids made from omega-3 fats reduce some of the key operations involved in atherosclerotic development and heart attacks. For instance, one prostaglandin called prostacyclin or PGI2 is very potent inhibitor of blood clotting. This seems to be very significant as many heart attacks occur because blood clots form or become lodged in a narrowed coronary artery. Other omega-3 fatty acid based eicosanoids reduce inflammation, a key process in atherosclerosis and promote vasodilation to allow for better blood flow through heart arteries. Thus helps us understand why, individuals who eat diets higher in omega-3 fatty acids, such as certain Eskimo populations, show a lower incidence of heart disease. In general a ratio of around 4 to 1 (omega 6 to omega 3) is recommended.
Should fish oil supplements be used to promote a healthy cardiovascular system?
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At this time there is enough supporting research to suggest that anyone not consuming fish or other seafood should take a fish oil supplement to derive the beneficial omega-3 fats – DHA and EPA. In fact, many people are avoiding fish and other seafood today because of concerns related to the level of heavy metals such as mercury in seafood. Furthermore, the conversation of alpha-linolenic acid to EPA and DHA might not be as efficient as needed for optimal health, especially during certain situations such as in older people. People with high blood cholesterol (total and LDL) and triglyceride levels who take fish oil supplements might experience reductions in one or both, particularly the latter. |
Fish oil supplementation has also been suggested to lower blood pressure in people with high blood pressure as well as improving glucose tolerance in Type 2 diabetes. For many people, fish oil supplementation can modestly reduce blood pressure and with regard to improving glucose levels in people with Type 2 diabetes, more research is needed to better understand whether or not there is benefit.
Do trans fatty acids increase the risk of heart disease?
Trans fats are naturally found in low percentages in most animal fats, including milk and dairy products. These fats are made by bacteria in the stomachs of cows and other grazing animals, by converting cis unsaturated fatty acids in grass and leaves to trans. Also, when vegetable oils are hydrogenated, some of the points of unsaturation are converted from a cis to a trans design.
It does appear that trans fatty acids impact blood lipids in many people by raising total and LDL-cholesterol when compared to oils containing unsaturated fatty acids. In addition, HDL-cholesterol levels may also be reduced. Thus the important message is that trans fats can have an unhealthy effect similar to saturated fatty acids. Thus, one of the most potent ways to lower your total and LDL cholesterol is to limit saturated fat and trans fat levels in your diet.
