Effects of dietary n-3 polyunsaturated fatty acids from plant and marine origin on platelet aggregation in healthy elderly subjects

In the present intervention study we compared the effects of a-linolenic acid with those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on platelet aggregation in vitro and ex vivo in healthy non-institutionalized elderly subjects. We also compared the effects of a-linolenic acid on platelet aggregation in elderly subjects with those in younger volunteers. During a run-in period of 3 weeks all subjects (thirty-eight elderly (>60 years) and twelve younger volunteers (<35 years)) received a diet rich in oleic acid. For the next 6 weeks the elderly subjects received a diet rich in oleic acid (n =11), alpha-linolenic acid – ALA (n =14) (6-8 g/d) or EPA/DHA (n =13) (1.05 g EPA plus 0.55 g DHA). The younger subjects were given a diet rich in a-linolenic acid. The diets did not affect ADP- or collagen-induced platelet aggregation in vitro in either platelet-rich plasma or whole blood. The ex vivo platelet aggregation as measured with filtragometry was significantly decreased in the elderly group that received EPA/ DHA compared with the ALA (P = 0.006) and the oleic acid (P = 0.005) diet groups. Effects of ALA were not age-dependent. Our results suggest that a-linolenic acid and EPA/DHA do not change in vitro platelet aggregation. Compared with oleic acid, EPA/DHA, but not ALA, favourably affects ex vivo platelet aggregation in healthy elderly subjects. (Authors abstract)
Human studies comparing the effects of a-linolenic acid with those of EPA/DHA on platelet aggregation are scarce. In the present intervention study, the effects of a-linolenic acid were compared with those of EPA/ DHA on platelet aggregation in healthy elderly subjects (60 years and older). A group of subjects younger than 35 years was also included. Whether the potential effects of ALA on platelet aggregation are age-dependent was also examined. The results suggest that ALA and EPA/DHA do not change in vitro platelet aggregation in whole blood or PRP, and that EPA/DHA, but not ALA, favourably affects ex vivo platelet aggregation compared with oleic acid. The effects of ALA were found not to be age-dependent. Differences in the fatty acid composition of the diets were reflected by the fatty acid composition of erythrocyte neutral phospholipids, indicating good dietary compliance. (Editors comments)