Polyunsaturated Fatty Acids
Polyunsaturated fatty acids (PUFAs) are fatty acids with more than one double bond. Since double bonds may be oxidized, the more double bonds there are in a fatty acid, the more susceptable it is to lipid peroxidation; PUFAs are the most susceptable, those with a lone double bond (MonoUnsaturated Fatty Acids or MUFAs) being less so, and saturated fatty acids being mostly immune to oxidation under standard conditions.[439][440]
It has been noted that while an increase in lipid peroxidation (which occurs from oral ingestion of high doses of PUFA which are then integrated into organ tissue[441][442]) from feeding rats PUFAs is not as high as expected, this difference is not completely accounted for by vitamin E levels in rats given adequate vitamin E intake in the short term,[443][444] although a vitamin E-deficient diet clearly does lead to increased peroxidation and damage. [445] It is thought by some, however, that increasing dietary PUFAs may increase the requirement of vitamin E.[446][447] The increased need of vitamin E is known to correlate with the degree of fatty acid unsaturation, with more highly-saturated PUFAs reducing vitamin E stores more.[448]
An adequate oral intake of vitamin E in humans has been estimated to be 0.6mg (approximately 1 IU) of α-tocopherol per gram of linoleic acid[447] and may be higher for fatty acids with more than two double bonds (most dietary PUFAs).[447]
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