PIP: Vitamin B6 (pyridoxine hydrochloride) is contained in most prenatal and multivitamin preparations. Available research states that pyridoxine blocks lactation and inhibits the secretion of breast milk in nursing mothers by suppressing the normally elevated prolactin hormone levels encountered during puerperium. The physiologic mechanism by which pyridoxine exerts its effects is still mostly pure conjecture. According to the author, nursing mothers should take only multivitamins with essential minerals that do not include pyrodoxine. This is especially significant for areas of the world where the threat of malnutrition is present.