Kallio M J, Siimes M A, Perheentupa J, Salmenperä L, Miettinen T A
Children's Hospital, Helsinki, Finland.
Am J Clin Nutr. 1989 Oct;50(4):782-5. doi: 10.1093/ajcn/50.4.782.
Concentrations of cholesterol and its precursors were investigated in human milk from 88 mothers at 2 mo, 28 mothers at 6 mo, and 6 mothers at 9 mo of lactation. These mothers, who were exclusively breast-feeding their infants, collected fore- and hindmilk samples at every feeding over a 24-h period. Samples were analyzed by gas-liquid chromatography and mass spectrometry. Mean (+/- SD) cholesterol concentrations were 0.41 +/- 0.094, 0.46 +/- 0.094, and 0.49 +/- 0.10 mmol/L, respectively. The following cholesterol precursors were identified: squalene, lanosterol, dimethylsterol, delta 8.24-methostenol, lathosterol, and desmosterol. Mean concentrations were 0.04 +/- 0.11, 0.35 +/- 0.13, and 0.29 +/- 0.012 mmol/L for desmosterol, 0.0094 +/- 0.0027, 0.012 +/- 0.0039, and 0.011 +/- 0.0039 mmol/L for squalene, and from 0.0011 to 0.0027 mmol/L for all the other precursors. The precursors' equally low concentrations, except for desmosterol and squalene, and the significant correlations with each other suggest that the mammary gland synthesizes cholesterol from lanosterol by preserving the side-chain double bond and that the rate-limiting step may be the conversion of desmosterol to cholesterol.
对88名母亲产后2个月、28名母亲产后6个月以及6名母亲产后9个月的母乳中的胆固醇及其前体浓度进行了研究。这些母亲均为纯母乳喂养婴儿，她们在24小时内每次喂奶时收集前奶和后奶样本。样本通过气液色谱法和质谱法进行分析。胆固醇平均（±标准差）浓度分别为0.41±0.094、0.46±0.094和0.49±0.10 mmol/L。鉴定出了以下胆固醇前体：角鲨烯、羊毛甾醇、二甲基甾醇、δ8,24-甲甾烯醇、羊毛甾醇和胆甾烯醇。胆甾烯醇的平均浓度分别为0.04±0.11、0.35±0.13和0.29±0.012 mmol/L，角鲨烯的平均浓度分别为0.0094±0.0027、0.012±0.0039和0.011±0.0039 mmol/L，其他所有前体的浓度在0.0011至0.0027 mmol/L之间。除胆甾烯醇和角鲨烯外，其他前体的浓度同样较低，且彼此之间存在显著相关性，这表明乳腺通过保留侧链双键从羊毛甾醇合成胆固醇，限速步骤可能是胆甾烯醇向胆固醇的转化。
