Wednesday 26 March 2014

Omega-3: Fish Versus Plant Source

Omega-3 fatty acids are cardioprotective. These special molecules are a group of fatty acids with multiple double bonds, and this structural characteristic gives them important physiological properties. In particular, omega-3 fatty acids can be converted into hormone-like substances called eicosanoids, that are able to regulate cell function. In doing so, they can reduce inflammation and platelet aggregation, which explains their cardioprotective effects.

Plant Source Omega-3

Plant derived omega-3 fatty acids are in the form of the essential fatty acid alpha linolenic acid (ALA). Humans metabolise ALA using enzymes by elongating the molecule and adding double bonds. Two of the fatty acids that ALA can be metabolised to are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both EPA and DHA can further be metabolised to eicosanoids that have beneficial cellular effects.

Fish Oils

Fatty fish contain both EPA and DHA. Therefore if fish is consumed plant source omega-3 is not required in the diet. Eating fatty fish, or consuming fish oil capsules containing EPA and DHA are both effective ways to get enough omega-3 fatty acids in the diet. Vegetarians don’t have much choice with regards their source of omega-3 fatty acids as they can't eat fish. However, for omnivorous humans, the choice presents a dilemma.

Fish Is Polluted

Evidence shows that the World’s waterways are becoming polluted. This pollution bioaccumulates in organisms, which results in those at the top of the food chain being the most polluted. Cold water predator fish therefore accumulate significant levels of pollution and this is passed onto humans when they consume the fish for their oil. Eating fatty fish or taking fish oil capsules can therefore increase exposure to pollution.

ALA Is Poorly Converted to EPA and DHA

Because consumption of fish may be problematic with respect to increasing intake of pollutants, it might be considered that plants source ALA is a better option. However, ALA is poorly converted to EPA and DHA in humans, and most of the intake of dietary ALA is actually burnt as a fuel. Therefore consuming ALA doesn’t provide the same level of cardioprotection as consuming EPA and DHA from fish oil supplements.

Fish Oils Are More CardioProtective That Plant ALA

When considering the facts, it becomes clear that fish oil is a far superior cardioprotective that ALA from plants. However the pollution is problematic. One way round this is to consume DHA from algae grown in pollution free tanks. However, this source of DHA is expensive. Another alternative is to find a brand of fish oils that have had the pollutants removed. Eating fish from non-polluted waterways is also advisable, if they can be found.

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