Thursday, March 26, 2009

Omega-3 Fatty Acids Revisited

A couple of weeks ago I wrote about flaxseed oil and the fact that ALA (alpha-linolenic acid) is not efficiently converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). To be honest, I'm not up on the literature on fatty acid metabolism - its a complex field in nutrition research. But, a recent report published by the International Society for the Study of Fatty Acids and Lipids (ISSFAL) delivered the scientific evidence that consumption of ALA does not deliver the same health benefits as other omega-3* fatty acids. Why ? Because the conversion of ALA to DHA is very low, and the evidence suggests that it is the long-chain n-3 fatty acids (EPA, DHA) that confer the health benefits.
* also know as n-3

What does this mean ? Taking flaxseed oil may not be delivering the health benefits you think!

But what about other plant based oils ? One reader of the blog brought my attention to echium seed oil. Keep in mind, not all sources of n-3 fatty acids are created equally (to complicate things!). Back to nutritional biochemistry - for those interested....
The fatty acid composition of echium oil is different to flaxseed as it contains both ALA and stearidonic acid (SDA) [the desaturation product of ALA], as well as the some omega-6 fatty acids, linoleic acid (LA) and γ-linolenic acid (GLA).

So in essence, echium oil is unusual because it contains substantial amounts of polyunsaturated fatty acids (PUFA) and different types of PUFA (i.e. both n-3 and n-6 fatty acids). So consuming this plant-based oil may deliver different health benefits. The fatty acid, SDA, may have similar biological properties to EPA (the major n-3 fatty acid in fish oil). This should be discussed in a future blog i.e. the health benefits to consuming echium oil.

So what's my bottom-line: In a past blog I had stated
"If you are a vegan/vegetarian, including plant sources of n-3's in your diet is essential, and you should eat flaxseed oil and other sources of ALA".
But based on my recent readings, I'm not sure taking flaxseed oil is really delivering any health benefits. It appears that the conversion of ALA to DHA is very low. Since our bodies are reliant on DHA from dietary/supplement sources, the best of which are marine-based, I'm back to encouraging you to eat fish and fish oil supplements.

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