Dietary total antioxidant capacity and mortality in the PREDIMED study

The aim of the present study was to assess the association between the dietary total antioxidant capacity, the dietary intake of different antioxidants and mortality in a Mediterranean population at high cardiovascular disease risk. A total of 7,447 subjects from the PREDIMED study (multicenter, parallel group, randomized controlled clinical trial), were analyzed treating data as an observational cohort. Different antioxidant vitamin intake and total dietary antioxidant capacity were calculated from a validated 137-item food frequency questionnaire at baseline and updated yearly. Deaths were ascertained through contact with families and general practitioners, review of medical records and consultation of the National Death Index. Cox regression models were fitted to assess the relationship between dietary total antioxidant capacity and mortality. Dietary total antioxidant capacity was estimated using ferric-reducing antioxidant power assays. A total of 319 deaths were recorded after a median follow-up of 4.3 years. Subjects belonging to the upper quintile of antioxidant capacity were younger, ex-smokers, with high educational level, and more active and had higher alcohol intake. Multivariable-adjusted models revealed no statistically significant difference between total dietary antioxidant capacity and mortality (Q5 vs. Q1 ref HR 0.85; 95 % CI 0.60-1.20) neither for the intake of all the vitamins studied. No statistically significant association was found between antioxidant capacity and total mortality in elderly subjects at high cardiovascular risk.