Omega 3: Fish, plants or Algae?

Omega 3 fatty acids are cardioprotective. In particular regular consumption of omega 3 fatty acid may lower triglyceride levels. This is because omega 3 fatty acids can increase the oxidation of other fatty acids in the liver and this reduces the production of triglycerides. In addition, omega 3 fatty acids are converted to anti-inflammatory hormones called eicosanoids and this has a protective effect on arteries and inhibits platelet aggregation. However, controversy surrounds the best dietary source of omega 3 fatty acids.


Plants contain the omega 3 fatty acid alpha linolenic acid. This is the parent omega 3 fatty acid which is converted to other longer more unsaturated omega 3 fatty acids in the body, including eicosapentaenoic acid and docosahexaenoic acid. In turn these fatty acids form a number of anti-inflammatory eicosanoid hormones. However, the alpha linolenic acid in plants is not well converted and alpha linolenic acid could be considered a poor source of omega 3 fatty acids.


Fish contain preformed eicosapentaenoic acid and docosahexaenoic acid. This means that eating fish sidesteps the rate limiting step that inhibits the conversion of alpha linolenic acid to anti-inflammatory eicosanoids. Fish is therefore a better source of omega 3 fatty acids and has better anti-inflammatory effects than plants. However, fish accumulate toxins and pollutants, and larger fish such as swordfish and tuna can be particularly polluted. Farmed salmon also contain high amounts of toxins and is not recommended.

Fish Oil Capsules

Eicosapentaenoic acid and docosahexaenoic acid are also available in fish oil capsules. Each capsule can supply a similar amount of omega 3 fatty acids as might be present in a large portion of fish. However, the toxins and pollutants in fish make their way into the capsules, unless special chemical processes are used to remove them. For this reason cheaper fish oil capsules are often no better than eating the fish from which the pill was extracted, and might therefore contain considerable pollution.

Smaller Fish

Bioaccumulation describes the gradual increases in concentration that occur for a substance as it moves up the food chain, particularly pollution. The animals at the top of the food chain are the most polluted and the ones at the bottom of the food chain the least polluted. Smaller fish such as mackerel, sardines (pilchards) and anchovies are a better of omega 3 fatty acids than larger fish because they are lower down the food chain and therefore have lower levels of pollutants.


Algae are small plants that synthesise their own preformed docosahexaenoic acid. This is the source of the docosahexaenoic acid that accumulates in fish (who eat the algae). Algae are now grown in tanks specifically for the purpose of making supplements containing docosahexaenoic acid. Because they are grown in tanks, their environment is controlled, and therefore they can be kept free of pollutants. Although at present expensive, this is probably the most effective source of omega 3 fatty acids, because it provides clean unpolluted performed docosahexaenoic acid. .


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