Increased levels of oxidative stress have been implicated in tissue damage and the development of chronic diseases, and dietary antioxidants may reduce the risk of oxidative tissue damage. As part of a European multicentre project, several studies were undertaken with the aim of testing whether the consumption of foods rich in carotenoids reduces oxidative damage to human tissue components. We describe here the serum response of carotenoids and tocopherols upon supplementation with carotenoids from natural extracts (α-carotene+β-carotene, lutein or lycopene; 15mg/day) and/or with α-tocopherol (100mg/day) in a multicentre, placebo-controlled intervention study in 400healthy male and female volunteers, aged 25-45 years, from five European regions (France, Northern Ireland, Republic of Ireland, The Netherlands and Spain). Supplementation with α-tocopherol increased serum α-tocopherol levels, while producing a marked decrease in serum γ-tocopherol. Supplementation with α- + β-carotene (carotene-rich palm oil) resulted in 14-fold and 5-fold increases respectively in serum levels of these carotenoids. Supplementation with lutein (from marigold extracts) elevated serum lutein (approx. 5-fold), zeaxanthin (approx. doubled) and ketocarotenoids (although these were not present in the supplement), whereas lycopene supplementation (from tomato paste) resulted in a 2-fold increase in serum lycopene. The isomer distributions of β-carotene and lycopene in serum remained constant regardless of the isomer composition in the capsules. In Spanish volunteers, additional data showed that the serum response to carotenoid supplementation reached a plateau after 4 weeks, and no significant side effects (except carotenodermia) or changes in biochemical or haematological indices were observed throughout the study. This part of the study describes dose-time responses, isomer distribution, subject variability and side effects during supplementation with the major dietary carotenoids in healthy subjects.

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