Mother’s Milk Found to Be Potent Cocktail Of Hormones
By NATALIE ANGIER
AS scientists lately have struggled to learn exactly what human milk is made of, the list of ingredients has gotten so long that breast-feeding infants should be grateful their packages come without a food label.
Beyond the proteins, minerals, vitamins, fats and sugars needed for nourishment, there are antibodies in milk to help fend off infection during the early months, when the baby’s own immune system is still too weak to work; growth factors thought to help in tissue development and maturation; and an abundance of hormones, neuropeptides and natural opioids that may subtly shape the newborn’s brain and behavior.
Now researchers have found proof for what they have long suspected: not only does the breast extract potent hormones from the mother’s blood and concentrate them in the milk, as researchers have shown often happens; it also generates some of these hormones itself, to assure that a rich yet precisely calibrated supply of the compounds will end up in the infant’s food.
Reporting today in The Proceedings of the National Academy of Sciences, Dr. Yitzhak Koch and his colleagues at the Weizmann Institute of Science in Rehovot, Israel, have found that a gene in charge of producing an important brain hormone, gonadotropin-releasing hormone, is switched on in the mammary glands of nursing rats, but not in the breast tissue of virgin rats. The discovery is the first detection of a neural hormone being synthesized in the breast gland proper, rather than starting out in the mother’s brain or some other part of the body and ending up in the milk.