Long-term antioxidant supplementation has no effect on health-related quality of life: the randomized, double-blind, placebo-controlled, primary prevention SU.VI.MAX trial.

Randomized, double-blind, placebo-controlled primary prevention trial in healthy French adults. In the supplement arm, 6,364 participants were randomized, 5,316 completed the initial HRQoL questionnaire, and 4,081 had both baseline and final HRQoL data for analysis; the active-arm population included men aged 45-60 years and women aged 35-60 years.

Participants in the active arm received one daily capsule containing vitamin C 120 mg, vitamin E 30 mg, beta-carotene 6 mg, selenium 100 mg as selenium-enriched yeast, and zinc 20 mg as gluconate. Supplementation was long term, with a median duration of 77 months (range 45-93).

Long-term antioxidant supplementation did not improve health-related quality of life. Across SF-36, GHQ-12, and global health ratings, most between-group comparisons were not significant; the trial's main conclusion was that nutritional-dose antioxidant vitamins and minerals did not provide a meaningful HRQoL benefit. A sex-specific difference was noted for vitality in women (Group p=0.014), but this did not translate into an overall quality-of-life improvement. The intervention also showed no clear benefit on the mental or physical component summary scores.

Interpretation is limited by substantial attrition and missing final questionnaires, with analysis restricted to participants who completed both HRQoL assessments. The cohort was relatively healthy and middle-aged, which limits generalizability, and no between-group effect sizes or confidence intervals were reported for the HRQoL outcomes. Outcomes were self-reported and follow-up was long, increasing the chance that intervening health events influenced response patterns.