Carotenoid composition of human milk during the first month postpartum and the response to beta-carotene supplementation.

Background: Information is lacking regarding normal changes in milk carotenoid concentrations in healthy, well-nourished women during the first month of lactation.

Objectives: This study investigated milk carotenoid concentrations during days 4-32 postpartum and assessed the effects of maternal beta-carotene supplementation.

Design: Subjects (n = 21; aged 19-39 y) were randomly assigned to receive beta-carotene (30 mg/d) or placebo from days 4 to 32 postpartum. Each subject provided 8 diet records and 8 milk samples during the study. Diet records were analyzed for energy, macronutrients, vitamins A and E, and carotenoids. Milk samples were analyzed with HPLC for concentrations of carotenoids, retinol, and alpha-tocopherol. Data were analyzed by using repeated-measures analysis and orthogonal contrasts.

Results: No significant differences in average dietary intakes, body mass index, age, or parity were found between groups at baseline or after supplementation. Milk carotenoid concentrations decreased over time (P < 0.01), as did retinol and alpha-tocopherol concentrations (P < 0.003). Concentrations of most carotenoids decreased to those reported for mature milk by day 32 postpartum. Milk lutein concentrations remained elevated throughout the study compared with values reported for mature milk, whereas plasma lutein concentrations decreased significantly over time. beta-carotene supplementation did not significantly change the milk concentrations of beta-carotene, the other carotenoids, retinol, or alpha-tocopherol.

Conclusions: The lack of increase in milk beta-carotene despite supplementation suggests that transitional milk may be already nearly saturated with beta-carotene. The elevated milk lutein concentration and simultaneous decrease in plasma lutein suggest that lutein metabolism may be altered during early lactation.