Section 14
Chapter 13,100

Conflicting roles of polyunsaturated fatty acids

Sanders, T.A.; Naismith, D.J.

Lancet 1(8169): 654-655


ISSN/ISBN: 0140-6736
PMID: 6102657
DOI: 10.1016/s0140-6736(80)91147-2
Accession: 013099490

Both linoleic and linolenic acids are essential nutrients for humans, but the balance of the 2 polyunsaturated fatty acids must be considered as well as the pharmacological effects of consuming more than the small amounts needed. The long-chain derivatives of both are found in human tissues; an imbalance can result since metabolism utilizes a common enzyme system. The linoleic/linolenic ratio in the diet controls conversion of linolenic acid to its long-chain derivatives; an illustration is the plasma and erythrocyte lipids of vegans which are lower for 20:5, n-3 and 22:6, n-3 and higher for 20:4, n-6 and 22:4, n-6 when compared to omnivores. This ratio is estimated to be about 9:1 in the typical British diet. To change the ratio, a dietary source rich in linolenic acid is necessary, such as linseed oil, but its use is severely limited by its taste. The alternative is fatty fish or fish offal, which contain 20:5, n-3, but these do not enjoy widespread popularity. The feasible solution would be a fish oil supplement. However, the resulting tissue lipid composition changes must be analyzed in conjunction with other possible changes.

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