Carotenoids as biomarkers of fruit and vegetable intake in men and women

High fruit and vegetable (FAV) intake is associated with a lower prevalence of chronic diseases. Identifying the ideal number of FAV servings needed to reduce chronic disease risk is, however, difficult because of biases inherent to common self-report dietary assessment tools. The aim of our study was to examine the associations between daily FAV intake and plasma carotenoid concentrations in men and women enrolled in a series of fully controlled dietary interventions. We compiled and analysed data from a group of 155 men and 109 women who participated in six fully controlled dietary interventions and compared post-intervention fasting plasma carotenoid (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene, zeaxanthin) concentrations with regard to the daily FAV servings consumed by the participants. We found that plasma beta-cryptoxanthin, lutein and zeaxanthin concentrations were positively associated with daily FAV servings (P <= 0.005). However, daily FAV intake was negatively associated with plasma a-carotene (P < 0.0005) and lycopene (P < 0.0001) concentrations, whereas no association was noted with plasma beta-carotene. When men and women were analysed separately, we found that for any given number of FAV servings consumed women had higher circulating lutein concentrations compared with men (P < 0.01). Significant sex x FAV (P < 0.0001) and sex x dietary beta-cryptoxanthin (P < 0.0005) interactions were also noted favouring higher plasma beta-cryptoxanthin concentrations in women than in men for a given FAV consumption. Results from these fully controlled dietary feeding studies indicate that plasma beta-cryptoxanthin and lutein concentrations can be used as robust biomarkers of FAV consumption. They also suggest the existence of sex differences influencing circulating beta-cryptoxanthin and lutein concentrations following FAV consumption.