The oxidative balance score (OBS)
The OBS was constructed using baseline dietary information from a semi-quantitative 136-item food-frequency questionnaire (FFQ) repeatedly validated in Spain [This novel OBS was based on 12 a priori selected components including dietary and non-dietary lifestyle factors associated with oxidative balance, as either pro- or antioxidant exposures (Additional File 1: Table s1). The selection of these components was based on the latest existing evidence and information available from the FFQ and lifestyle questionnaire. Dietary intakes included total vitamin C, total vitamin E, beta-carotenes, selenium, total zinc, heme iron, polyphenol antioxidant content (PAC) score, and total antioxidant capacity (TAC), whereas lifestyle included BMI, alcohol intake, smoking status, and an 8-item physical activity score. Total intakes of vitamin C, vitamin E, and zinc included both diet and supplement intakes. The novelty of this OBS lies in the inclusion of supplementary intakes, and TAC and PAC components, which have not been previously included in other published OBS. PAC score was calculated based on a previous published score that assessed the polyphenol intake with a 7-item score by generating deciles of intakes for the included polyphenols class and subclass (flavonols, anthocyanins, flavanones, flavones, flavanols, isoflavonoids, and lignans intake) [