Blood samples (2 x 7 mls) will be collected into Vacutainer™ tubes for plasma. Platelet depleted plasma will be prepared by centrifugation at 1000g for 30 mins (4C). Plasma will be aliquoted into cryogenic vials and half will be snap frozen under liquid nitrogen until TOAC assay. The remaining half will be aliquoted into two 1.5ml cryogenic vials and stored at -80C for future use (e.g. assay for carotenoid activity). All samples will be stored in the dark and kept free from direct sunlight at all stages of handling.