Alpha-linolenic acid (ALA) is an essential fatty acid and the substrate for the synthesis of longer-chain, more unsaturated ω-3 fatty acids, eicosapentaenoic acid (EPA), docosapentaenoic acid and docosahexaenoic acid (DHA). EPA and DHA are associated with human health benefits. The primary source of EPA and DHA is seafood. There is a need for sustainable sources of biologically active ω-3 fatty acids. Certain plants contain high concentrations of ALA and stearidonic acid (SDA). Here we review the literature on the metabolism of ALA and SDA in humans, the impact of increased ALA and SDA consumption on concentrations of EPA and DHA in blood and cell lipid pools, and the extent to which ALA and SDA might have health benefits. Although it is generally considered that humans have limited capacity for conversion of ALA to EPA and DHA, sex differences in conversion to DHA have been identified. If conversion of ALA to EPA and DHA is limited, then ALA may have a smaller health benefit than EPA and DHA. SDA is more readily converted to EPA and appears to offer better potential for health improvement than ALA. However, conversion of both ALA and SDA to DHA is limited in most humans.

α-亚麻酸（ALA）是必不可少的脂肪酸，是合成长链，更不饱和的ω-3脂肪酸，二十碳五烯酸（EPA），二十二碳五烯酸和二十二碳六烯酸（DHA）的底物。EPA和DHA与人类健康有关。EPA和DHA的主要来源是海鲜。需要生物活性ω-3脂肪酸的可持续来源。某些植物含有高浓度的ALA和十八碳四烯酸（SDA）。在这里，我们回顾了有关人类中ALA和SDA代谢，ALA和SDA消耗量增加对血液和细胞脂质池中EPA和DHA浓度的影响以及ALA和SDA可能对健康产生影响的程度的文献。尽管通常认为人类将ALA转换为EPA和DHA的能力有限，已确定转换为DHA的性别差异。如果将ALA转换为EPA和DHA受到限制，则ALA的健康益处可能比EPA和DHA小。与ALA相比，SDA更容易转化为EPA，并且似乎具有更好的健康改善潜力。但是，在大多数人中，ALA和SDA两者向DHA的转化均受到限制。