摘要 : Background: In mammals the composition of milk changes during early lactation showing a rapid decline in fat-soluble vitamins and a continuous increase in total lipids. Changes in the concentrations of carotenoids, vitamin A, a-to... 展开 Background: In mammals the composition of milk changes during early lactation showing a rapid decline in fat-soluble vitamins and a continuous increase in total lipids. Changes in the concentrations of carotenoids, vitamin A, a-tocopherol and total lipids in human milk (colostrum, transitory and mature milk) were studied to understand this not well characterised phenomenon. Methods: Colostrum, transitory and mature milk was collected from 21 women and analysed for carotenoids, vitamin A and a-tocopherol by HPLC. Results: Total lipids increased from the lowest levels in colostrum (1.5 +/- 1.6 mg/ml)to the highest in transitory milk(3.6 +/- 2.5 mg/ml, p < 0.01). Contrary to this, levels of total carotenoids (236.7 +/- 121.9 ng/ml), vitamin A (1.02 +/- 0.56 mug/ml) and a-tocopherol (11.8 +/- 6.3 mug/ml) were highest in colostrum and declined significantly during the first weeks of lactation (63.2 +/- 23.3 ng/ml, 0.33 +/- 0.14 mug/ml, 2.7 +/- 1.1 mug/ml, respectively; p < 0.001), Conclusions: The magnitude of decrease was not the same for all carotenoids a nd was dependent on the polarity of the carotenoid with the smallest decrease in the polar carotenoids, This might be due to differences in the distribution of carotenoids among plasma lipoproteins and might point to possible selective mechanisms being involved in the transfer of these components in early human milk. 收起