Hormonal Substances in Human Milk, Cow's Milk and Dairy Products

Hormone-like substances are normal constituents of cow's and human milk. Progesterone has been quantified in cow's milk and dairy products with butter containing a high value of 300 ng/g. Estrogenic substances have been detected in cow's and human milk but literature values are sparse or tend to vary widely possibly because quanitative methods available lacked specificity and sensitivity. Pregnanediol is rather unique to human milk and its presence in elevated levels has been associated with prolonged neonatal jaundice of nursing infants. The concentration of this steroid in affected mother's milk appears to be in the range of 150-450 ng/ml. 17-Ketosteroids may be present in cow's and human milk but here again limited literature values vary widely. Corticoids have been reported in cow's milk at a concentration of 3.1-3.7 ng/ml. Thyroxine and triiodothyronine are present in human milk but practically undetectable in cow's milk. Prostaglandins (PGF₂α) have been determined to be present in cow's milk at concentrations between 0.1 to 0.4 ng/ml.