Soybeans are the largest source of edible oils in the U.S., and, as of a 2007 study, 40% of soy oil production was partially hydrogenated. Oxidative instability of α-linolenic acid is one reason why producers choose to partially hydrogenate oils containing α-linolenic acid, such as soybean oil. Stability and hydrogenation Ĭompared to many other oils, α-Linolenic acid is more susceptible to oxidation and will become rancid more quickly. Conversion of ALA to DHA is higher in women than in men. īecause 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. These also can be synthesized by humans from dietary α-linolenic acid: ALA → stearidonic acid → eicosatetraeonic acid → eicosapentaenoic acid → docosapentaenoic acid → 9,12,15,18,21-tetracosapentaenoic acid → 6,9,12,15,18,21-tetracosahexaenoic acid → docosahexaenoic acid, but with an efficiency of only a few percent. Eicosapentaenoic acid (EPA 20:5, n−3) and docosahexaenoic acid (DHA 22:6, n−3) are readily available from fish and algae oil, and play a vital role in many metabolic processes.
Α-Linolenic acid can be obtained by humans only through their diets, because the absence of the required 12- and 15-desaturase enzymes makes de novo synthesis from stearic acid impossible. There is a complex set of essential fatty acid interactions. Linoleic acid is the other essential fatty acid, but it, and the other n−6 fatty acids, compete with n−3s for positions in cell membranes and have very different effects on human health. Exceptions include flaxseed (must be ground for proper nutrient absorption) and chia seeds. Potential role in nutrition and health įlax is a rich source of α-linolenic acid.Īlthough the best source of ALA is seeds, most seeds and seed oils are much richer in an n−6 fatty acid, linoleic acid. ALA percentages in the table below refer to the oils extracted from each item. Some ALA may also oxidize at baking temperatures.
However, other studies state that ALA might not be suitable for baking as it will polymerize with itself, a feature exploited in paint with transition metal catalysts. Some studies state that ALA remains stable during processing and cooking. Plant chloroplasts consisting of more than 95 percent of photosynthetic thylakoid membranes are highly fluid due to the large abundance of ALA, evident as sharp resonances in high-resolution carbon-13 NMR spectra. α-Linolenic acid is also obtained from the thylakoid membranes in the leaves of Pisum sativum (pea leaves). Seed oils are the richest sources of α-linolenic acid, notably those of hempseed, chia, perilla, flaxseed ( linseed oil), rapeseed ( canola), and soybeans. See also: Vegetable oil § Composition of fats Oleic means "of or relating to oleic acid" because saturating linoleic acid's omega-6 double bond produces oleic acid. The word linolenic is an irregular derivation from linoleic, which itself is derived from the Greek word linon ( flax). It is an isomer of gamma-linolenic acid (GLA), an 18:3 ( n−6) fatty acid (i.e., a polyunsaturated omega-6 fatty acid with three double bonds). Thus, α-linolenic acid is a polyunsaturated n−3 (omega-3) fatty acid. The first double bond is located at the third carbon from the methyl end of the fatty acid chain, known as the n end. It is a carboxylic acid with an 18-carbon chain and three cis double bonds. In physiological literature, it is listed by its lipid number, 18:3, and ( n−3). In terms of its structure, it is named all- cis-9,12,15-octadecatrienoic acid. ALA is found in many seeds and oils, including flaxseed, walnuts, chia, hemp, and many common vegetable oils. Α-Linolenic acid, also known as alpha-Linolenic acid ( ALA) (from Greek alpha meaning "first" and linon meaning flax), is an n−3, or omega-3, essential fatty acid.
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