Impact of dietary vitamin A interventions on total body stores in Thai lactating women

Vitamin A deficiency (VAD) is increasingly being recognized as a public health problem among pregnant and lactating women in developing countries. This proposed study will be a randomized trial to evaluate the efficacy of consuming provitamin A-rich foods in one prepared, on-site meal per weekday for 3 months on total body vitamin A stores and other aspects of vitamin A status in marginally nourished lactating women in rural Northeast Thailand. Approximately 400 lactating women, 2-18 months post-partum, will be screened in the population for marginal vitamin A status by a tier of indicators beginning from low intake or history of night blindness or impaired dark adaptability followed by low serum retinol. Assuming a prevalence of low serum retinol of ∼20%, 90 women will be identified and recruited, matched by serum retinol and month post-partum and randomized in a block fashion into three groups to receive daily cooked (fat-added) meal and snack with (1) dark green leafy and yellow/orange vegetables and fruits, (2) beta-carotene- enriched rice chips and (3) non-enriched rice chips. Groups 1 and 2 will receive ∼3.6 mg of beta-carotene per day. Prior to and following the intervention hepatic vitamin A reserves will be estimated by isotopic dilution techniques and other indicators of vitamin A status. In addition, serum C-reactive protein and maternal anthropometry will be measured. Food consumption data based on 24-hour recall for 3 randomized days will be collected every 2 weeks to assess routine intakes of vitamin A, fat and other nutrients. Morbidity will be monitored on a weekly basis throughout the study. Between-group comparisons will provide a basis for (1) estimating the adequacy of local diets to improve or maintain total body stores of vitamin A in women during lactation and (2) assessing the validity and responsiveness of widely used measures of vitamin A status in this high-risk group