Although human can convert alpha-linolenic acid(ALA)to EPA and DHA, the conversion rate is so low, you need eat a lot of food contain ALA, that's make it impractical.

虽然人体可以自动将 α-亚麻酸（ALA） 转换成 二十碳五烯酸（EPA） 和 二十二碳六烯酸（DHA） ，但转换率很低，人们需要食用大量含有 α-亚麻酸（ALA） 的食品才行，这种做法可行性不高。

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But many foods that brag about being "an excellent source" of omega-3 fatty acids instead contain alpha-linolenic acid (ala), derived from nuts and flaxseeds.

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