Alpha-Linolenic acid

α-linolenic acid is a polyunsaturated n−3 (omega-3) fatty acid (ALA).

ALA is found in many seeds and oils, including flaxseed, walnuts, chia, hemp, and many common vegetable oils.

Seed oils are the richest sources of α-linolenic acid: hempseed, flaxseed (linseed oil), rapeseed (canola), and soybeans. 

ALA remains stable during processing and cooking, but might not be suitable for baking, as it will polymerize with itself.

Flax is a rich source of α-linolenic acid.

Most seeds and seed oils are much richer in an n−6 fatty acid, linoleic acid. 

Linoleic acid is the other essential fatty acid.

α-Linolenic acid can only be obtained by humans through their diets because of the absence of the required desaturase enzymes.

 Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are readily available from fish and algae oil and play a vital role in many metabolic processes. 

EPA and DHA can also be synthesized by humans from dietary α-linolenic acid.

The efficacy of n−3 long-chain polyunsaturated fatty acid (LC-PUFA) synthesis decreases down the cascade of α-linolenic acid conversion, DHA synthesis from α-linolenic acid is even more restricted than that of EPA.

Conversion of ALA to DHA is higher in women than in men.

Multiple  studies  reveal a relationship between α-linolenic acid and a small increased risk of prostate cancer. 

α-Linolenic acid is relatively more susceptible to oxidation and becomes rancid more quickly than many other oils. 

Oxidative instability of α-linolenic acid is one reason partially hydrogenate oils containing α-linolenic acid, such as soybean oil are utilized.

Soybeans are the largest source of edible oils in the U.S., and, 40% of soy oil production was partially hydrogenated.

Partially hydrogenated oils are part of the unsaturated fatty acids and become unhealthy trans fats. 

Low-α-linolenic acid soybeans yield a more stable oil that doesn’t require hydrogenation for many applications, thus providing trans fat-free products, such as frying oil.

A review suggested higher ALA consumption is associated with a moderately lower risk of cardiovascular disease, but wide variation in results exists.


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