Karra M V, Udipi S A, Kirksey A, Roepke J L
Am J Clin Nutr. 1986 Apr;43(4):495-503. doi: 10.1093/ajcn/43.4.495.
An increasing trend towards breast-feeding infants beyond 6 mo of age has been observed in this country. The present study was designed to examine the effect of extended lactation on the concentrations of vitamins B6 and C, free and total folacin, calcium, zinc, and magnesium. Forty mothers were studied from 7 months of lactation until they stopped breast-feeding. Subjects were requested to collect milk samples monthly at a morning feeding between 7 AM and 10 AM. Between 7 and 25 mo of lactation, levels of zinc, calcium, vitamin B6, and vitamin C tended to decrease, whereas levels of free and total folacin remained unchanged. Magnesium levels decreased only after 18 mo of lactation. The decrease in concentrations of zinc and calcium paralleled the decrease in feeding frequency. Changes observed in this study on the composition of human milk may reflect physiological changes in the mammary gland during weaning.
在该国，母乳喂养婴儿超过6个月的趋势日益明显。本研究旨在探讨延长哺乳期对维生素B6、维生素C、游离及总叶酸、钙、锌和镁浓度的影响。对40名母亲进行了研究，从哺乳期7个月直至她们停止母乳喂养。要求受试者每月在上午7点至10点的一次晨喂时采集乳汁样本。在哺乳期7至25个月期间，锌、钙、维生素B6和维生素C的水平趋于下降，而游离及总叶酸水平保持不变。镁水平仅在哺乳期18个月后下降。锌和钙浓度的下降与喂养频率的降低平行。本研究中观察到的人乳成分变化可能反映了断奶期间乳腺的生理变化。
