Background: Vegetarians have lower platelet and plasma concentrations of n-
3 polyunsaturated fatty acids (PUFAs) than do omnivores, We recently showed
that male vegetarians have higher platelet aggregability than do omnivores
.
Objective: We investigated whether male vegetarians (n = 17) who consumed a
n increased amount of dietary alpha-linolenic acid (ALA) showed any changes
in their tissue profile of PUFAs, plasma thromboxane concentrations, plate
let aggregability, or hemostatic factors.
Design: During the study, all subjects maintained their habitual vegetarian
diets except that a proportion of dietary fat 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) f
or 14 d; they then consumed either a moderate-ALA diet (containing canola o
il and canola oil-based margarine) or a high-ALA diet (containing linseed o
il and linseed oil-based margarine) for 28 d. Blood samples were collected
at day 0 (baseline), day 14, and day 42.
Results: Eicosapentaenoic acid, docosapentaenoic acid, total n-3 PUFAs, and
the ratio of n-3 to n-6 PUFAs were significantly increased (P < 0.05), whe
reas the ratio of arachidonic acid to eicosapentaenoic acid was decreased (
P < 0.05), in platelet phospholipids, plasma phospholipids, and triacylglyc
erols after either the moderate-ALA or high-ALA diet compared with the low-
ALA diet. No significant differences were observed in thrombotic risk facto
rs.
Conclusion: ALA from vegetable oils (canola and linseed) has a beneficial e
ffect on n-3 PUFA concentrations of platelet phospholipids and plasma lipid
s in vegetarian males.