alphalinolenic

Alpha-linolenic acid, commonly abbreviated ALA, is an essential polyunsaturated fatty acid in the omega-3 family. It has 18 carbons and three cis-double bonds (18:3n-3). As an essential nutrient, humans must obtain ALA from the diet because they cannot synthesize it endogenously.

ALA occurs primarily in plant sources such as flaxseed and flaxseed oil, chia seeds, walnuts, and hemp seeds, as well as certain vegetable oils such as canola and soybean oils. It can also be found in smaller amounts in leafy greens and fortified foods. These sources are commonly used in vegetarian and vegan diets to help meet omega-3 needs.

In humans, ALA can be converted through enzymatic desaturation and elongation to the longer-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, the conversion is limited and variable, with estimates typically indicating only a few percent of ALA is converted to EPA and even less to DHA. The efficiency of conversion is influenced by age, sex, and the intake of competing fatty acids such as linoleic acid.

Health considerations: ALA is essential for normal physiology and contributes to overall omega-3 status. Some observational and clinical studies associate higher ALA intake with modest cardiovascular benefits, but the effects are generally smaller than those of preformed EPA and DHA from marine sources. Dietary guidelines commonly encourage regular consumption of ALA-rich plant oils as part of a balanced diet.

Dietary notes: for individuals who do not consume fish, ALA provides a key omega-3 source. Supplements are available, but high-dose ALA supplementation should be discussed with a healthcare provider, as with other dietary fats, to ensure appropriate overall fat balance and safety.