Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men.

January 1, 1999 Human Health and Nutrition Data 0 Comments

Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men.

Year: 1999
Authors: D Li, A Sinclair, A Wilson, S Nakkote, F Kelly, L Abedin, N Mann, A Turner.
Publication Name: Am. J. Clin. Nutr.
Publication Details: Volume 69; Number 5; Page 872.


The predominant PUFA in the Western diet is LA which is commonly found in vegetable seed oils. ALA on the other hand is much less abundant than LA and is important as the precursor of 20- and 22-carbon n-3 long chain PUFAs. A diet with a low ratio of n-3 to n-6 PUFAs can cause a reduced tissue n-3 to n-6 ratio, which may lead to increased thrombotic tendency. Vegetarians have lower platelet and plasma concentrations of n-3 PUFAs than do omnivores due, in part, to the lack of fatty fish and fish oils in the diet. The authors have previously shown that male vegetarians have higher platelet aggregability than do omnivores. The objective of the present study was to examine the effect dietary ALA on atherosclerotic and thrombotic risk factors including tissue profile of PUFAs, plasma thromboxane concentrations, platelet aggregability, and hemostatic factors. Twenty-five free-living, healthy male vegetarians took part in the study. A proportion of dietary fat in their habitual diet was replaced with vegetable oils and margarines that were provided. Initially, all subjects consumed a low-ALA diet (containing safflower oil and safflower oil-based margarine) for 14 days, followed by either a moderate-ALA diet (containing CO and CO-based margarine) or a high-ALA diet (containing flaxseed oil and flaxseed oil-based margarine) for 28 days. After 42 days, results showed that increased dietary ALA from either CO or flaxseed oil led to a significant increase in EPA, DPA, total n-3 PUFAs and n-3:n-6 PUFAs in platelet and plasma PLs and plasma TGs. The AA to EPA ratio was reduced after the moderate or high ALA diets compared with the low ALA diet. There were no significant differences seen in thrombotic risk factors. This study supports the use of flaxseed and CO as sources of ALA by vegetarians to improve the n-3 PUFA content of platelet and plasma lipids thus reducing overall risk factors for atherosclerosis and thrombosis.

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