Setchell K D, Zimmer-Nechemias L, Cai J, Heubi J E
Clinical Mass Spectrometry Center, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
Lancet. 1997 Jul 5;350(9070):23-7. doi: 10.1016/S0140-6736(96)09480-9.
The isoflavones genistein, daidzein, and their glycosides, found in high concentrations in soybeans and soy-protein foods, may have beneficial effects in the prevention or treatment of many hormone-dependent diseases. Because these bioactive phyto-oestrogens possess a wide range of hormonal and non-hormonal activities, it has been suggested that adverse effects may occur in infants fed soy-based formulas.
To evaluate the extent of infant exposure to phyto-oestrogens from soy formula, the isoflavone composition of 25 randomly selected samples from five major brands of commercially available soy-based infant formulas were analysed, and the plasma concentrations of genistein and daidzein, and the intestinally derived metabolite, equol, were compared in 4-month-old infants fed exclusively soy-based infant formula (n = 7), cow-milk formula (n = 7), or human breast-milk (n = 7).
All of the soy formulas contained mainly glycosides of genistein and daidzein, and the total isoflavone content was similar among the five formulas analysed and was related to the proportion of soy isolate used in their manufacture. From the concentrations of isoflavones in these formulas (means 32-47 micrograms/mL), the typical daily volume of milk consumed, and average bodyweight, a 4-month-old infant fed soy formula would be exposed to 28-47 per day, or about 4.5-8.0 mg/kg bodyweight per day, of total isoflavones. Mean (SD) plasma concentrations of genistein and daidzein in the seven infants fed soy-based formulas were 684 (443) ng/mL and 295 (60) ng/mL, respectively, which was significantly greater (p < 0.05) than in the infants fed either cow-milk formulas (3.2 [0.7] and 2.1 [0.3] ng/mL), or human breast-milk (2.8 [0.7] and 1.4 [0.1] ng/mL), and an order of magnitude higher per bodyweight than typical plasma concentrations of adults consuming soy foods.
The daily exposure of infants to isoflavones in soy infant-formulas is 6-11 fold higher on a bodyweight basis than the dose that has hormonal effects in adults consuming soy foods. Circulating concentrations of isoflavones in the seven infants fed soy-based formula were 13000-22000 times higher than plasma oestradiol concentrations in early life, and may be sufficient to exert biological effects, whereas the contribution of isoflavones from breast-milk and cow-milk is negligible.
大豆和大豆蛋白食品中富含的异黄酮染料木黄酮、大豆苷元和它们的糖苷，可能对预防或治疗许多激素依赖性疾病具有有益作用。由于这些生物活性植物雌激素具有广泛的激素和非激素活性，有人提出食用大豆配方奶粉的婴儿可能会出现不良反应。
为评估婴儿从大豆配方奶粉中接触植物雌激素的程度，分析了从五个主要品牌的市售大豆基婴儿配方奶粉中随机抽取的25个样本的异黄酮成分，并比较了仅食用大豆基婴儿配方奶粉（n = 7）、牛奶配方奶粉（n = 7）或母乳（n = 7）的4个月大婴儿的血浆染料木黄酮和大豆苷元浓度以及肠道衍生代谢物雌马酚的浓度。
所有大豆配方奶粉主要含有染料木黄酮和大豆苷元的糖苷，在所分析的五种配方奶粉中，总异黄酮含量相似，且与生产中使用的大豆分离蛋白比例有关。根据这些配方奶粉中的异黄酮浓度（平均32 - 47微克/毫升）、婴儿每天饮用的典型奶量以及平均体重，食用大豆配方奶粉的4个月大婴儿每天接触的总异黄酮量为28 - 47微克/天，或约4.5 - 8.0毫克/千克体重/天。食用大豆基配方奶粉的7名婴儿中，染料木黄酮和大豆苷元的平均（标准差）血浆浓度分别为684（443）纳克/毫升和295（60）纳克/毫升，显著高于食用牛奶配方奶粉（3.2 [0.7]和2.1 [0.3]纳克/毫升）或母乳（2.8 [0.7]和1.4 [0.1]纳克/毫升）的婴儿，且按体重计算比食用大豆食品的成年人的典型血浆浓度高一个数量级。
婴儿每天从大豆婴儿配方奶粉中接触的异黄酮量按体重计算比食用大豆食品的成年人产生激素效应的剂量高6 - 11倍。食用大豆基配方奶粉的7名婴儿中异黄酮的循环浓度比生命早期的血浆雌二醇浓度高13000 - 22000倍，可能足以产生生物学效应，而母乳和牛奶中的异黄酮贡献可忽略不计。
