QUESTIONNAIRE ASSESSMENT OF INTAKE OF SPECIFIC CAROTENOIDS

We determined whether estimation of intake of specific carotenoids wit h a standard food-frequency questionnaire (FFQ) could be improved by c ollection of additional data on the intake of carotenoid-rich food ite ms. The foods included on an addendum to the standard FFQ were potenti ally important dietary contributors of alpha- and beta-carotene, beta- cryptoxanthin, lutein, zeaxanthin, or lycopene. Participants (n = 215) , ages 50-74 years, provided fasting blood samples and completed the F FQ and the addendum. The participants were enrolled in a prepaid healt h plan and had undergone screening sigmoidoscopy for detection of colo rectal polyps. Addendum foods were identified that accounted for varia tion in blood levels of specific carotenoids, conditional on intake of foods on the standard FFQ. Estimated carotenoid intakes from the stan dard FFQ, and from the modified FFQ with the selected addendum foods, were examined in relation to plasma carotenoid levels. The correlation coefficient between estimated carotenoid intake and plasma levels (ad justed for age, sex, serum cholesterol, alcohol intake, smoking status , and energy intake) were essentially the same for the standard and mo dified FFQs. The adjusted correlations for the standard FFQ only were 0.26 for alpha-carotene, 0.22 for beta-carotene, 0.36 for beta-cryptox anthin, 0.32 for lutein + zeaxanthin, and 0.34 for lycopene. Adding ca rotenoid-rich foods to the FFQ did not improve estimation of intake fo r the carotenoids examined in this population. We conclude that assess ment of intake of specific carotenoids with the FFQs currently in use may not necessarily be improved by a modified list of carotenoid-rich foods.