Linoleic acid (LA) is the only essential omega-6 fatty acid and must be obtained from the diet.
From LA, other omega-6s can be created using elongase and desaturase enzymes. LA contains 18 carbons, with 2 double bonds, the first of which is at the 6th carbon position (18:2n6).
LA is found in nuts and vegetable oils (corn, soybean, canola, sunflower, etc.) as well as most meats. When the double bonds of LA are arranged differently, the term conjugated LA (CLA) is used. Although technically CLA can be termed a trans-fat, a natural type of CLA can be obtained in the dietary intake of meat and milk from ruminant animals. There are many isomers of CLA – some beneficial and others are not as well defined. There is some controversy regarding how much LA is needed from the diet for adequacy. Although LA is needed to synthesize downstream fatty acids, it may lead to increased inflammatory fatty acid production.
Several studies show that LA lowers blood cholesterol levels and improves all-cause mortality However, their current role in atherosclerosis and cardiometabolic disease are being revisited. There is difficulty in differentiating the biological effects of LA from arachidonic acid in health and disease. In fact, it has been shown that LA is the most abundant fatty acid found in LDL and is one of the first fatty acids to oxidize.
Studies are showing that LA promotes oxidative stress, oxidized LDL, and may be a major dietary cause of cardiovascular disease, especially when consumed via industrial vegetable oils.
References:
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Linoleic (LA) 18:2 n6
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