TOTAL RADICAL-TRAPPING ANTIOXIDANT POTENTIAL (TRAP) OF PLASMA - EFFECTS OF SUPPLEMENTATION OF YOUNG HEALTHY-VOLUNTEERS WITH LARGE DOSES OF ALPHA-TOCOPHEROL AND ASCORBIC-ACID

A randomized, placebo-controlled double-blind supplementation trial wa s conducted on 32 adults to assess the effect of dl-alpha-tocopherol ( 1 g/day for 28 days) or ascorbic acid (AA) (1 g/day for 28 days) separ ately or in combination on the total radical-trapping antioxidant pote ntial (TRAP) of plasma. Subjects were divided into 4 groups of 8 and r eceived the following: Group 1, placebo, Group 2, ascorbic acid; Group 3, alpha-tocopherol; Group 4, alpha-tocopherol and AA. Antioxidant po tential was assessed using the TRAP technique (a specific measure of t he capacity of the secondary antioxidants, vitamins E, C, reduced thio l compounds and urate in plasma to resist controlled in vitro peroxida tion). TRAP values were estimated at baseline and after treatment (day 29). Group means of the antioxidant vitamins at baseline were within normal values for both ascorbic acid (62-82 mumol/l) and alpha-tocophe rol (24-29 mumol/l). Despite marked increases post-supplementation in plasma alpha-tocopherol levels in Groups 3 (94%) and 4 (91%) and in AA levels in Groups 2 (82%) and 4 (32%), there were no significant diffe rences (analysis of variance) between the 4 treatment groups for TRAP values on day 29. Paired-t-testing revealed significant (P < 0.01) inc reases in postsupplementation TRAP values in Groups 2 and 3.