title: The influence of antioxidant nutrients on platelet function in healthy volunteers.
abstract: There is mounting evidence that antioxidants may help to prevent coronary heart disease and modulate some thrombotic events such a platelet adhesion. However, the effects of antioxidant supplementation on platelet function in vivo are controversial. A double-blind, randomised, placebo-controlled study was performed on 40 healthy volunteers (20-50 years) supplemented daily with vitamin E (300 mg), vitamin C (250 mg) or beta-carotene (15 mg) for 8 weeks. Platelet function was assessed by platelet aggregation induced by ADP, arachidonic acid or collagen, platelet responsiveness to the inhibitor PGE1, beta-thromboglobulin release and ATP secretion. Supplementation with vitamin E resulted in a significant increase in platelet alpha-tocopherol level (+68%) reflecting closely the increase in plasma alpha-tocopherol level (+69%). Platelet function was significantly decreased by vitamin E as revealed by the decreased platelet aggregation in response to ADP and arachidonic acid, the increased sensitivity to inhibition by PGE1, the decreased plasma beta-thromboglobulin concentration and the decreased ATP secretion. Supplementation with vitamin C did not affect platelet function significantly although a trend towards a decreased platelet aggregability and an increased sensitivity to the inhibitor PGE1 were observed. No significant changes in platelet function occurred after supplementation with beta-carotene. In conclusion, supplementation of healthy volunteers with vitamin E decreased platelet function whereas supplementation with vitamin C or beta-carotene had no significant effects.
authors.affiliation: Division of Biochemistry and Molecular Biology, UMDS-Guy's Hospital, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Calzada
authors.forename: K R
authors.initials: KR
authors.lastname: Bruckdorfer
authors.forename: C A
authors.initials: CA
authors.lastname: Rice-Evans
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000527:Alprostadil / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D016718:Arachidonic Acid / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology; D019207:beta Carotene / Q000494:pharmacology; D001620:beta-Thromboglobulin / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010975:Platelet Aggregation Inhibitors; D001620:beta-Thromboglobulin; D019207:beta Carotene; D014810:Vitamin E; D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003094:Collagen; D000527:Alprostadil; D001205:Ascorbic Acid