Vitamin Trader - Healthy Discounts on Quality Vitamins

Even healthy and well-nourished nursing mothers and their babies benefit from a certain amount of supplemental beta-carotene, according to a recent study at the University of Arizona Medical Center in Tucson.

A nursing mother's dietary beta-carotene converts to vitamin A in her body, providing her infant with a good source of the vitamin. In addition to contributing to an infant's growth and development, vitamin A-laden breast milk may also enhance overall immunity and confer long-term protection against chronic disease.

To determine just how beneficial beta-carotene may be, researchers divided 12 healthy nursing mothers ages 23 to 36 into two groups. Group one received a single 60-mg dose of beta-carotene; group two received 210 mg of beta-carotene.

On days 0, 1, 2, 4, 7 and 9, researchers measured blood- and breast-milk levels of beta-carotene, other major carotenoids, and vitamins A and E. The women's average blood levels of beta-carotene increased 4.1-fold after the 60-mg dose but only 4-fold after the 210-mg dose. Beta-carotene levels in breast milk followed a similar pattern, increasing 4.1-fold and 3-fold, respectively. Blood concentrations of beta-carotene peaked 24 hours after supplementation.

In both groups, milk concentrations continued to rise for two to three days; and for both milk and blood, beta-carotene remained near maximum concentrations for about four days. After eight days, blood and milk levels were still double the baseline beta-carotene concentrations. Beta-carotene supplementation had no effect on the other carotenoids measured, nor vitamins A and E. None of the women reported yellowing of skin or other adverse effects.

Noting that the higher dose of beta-carotene actually yielded lower levels in blood and breast milk, the authors concluded that doses above 60 mg are unlikely to benefit well-nourished nursing women and 30 mg may be closer to an optimal dose. The authors noted that their study results agreed with earlier findings that blood levels of beta-carotene are not proportional to dose and that absorption actually decreases with larger doses. They did not speculate why this happens. Their next step is to determine if supplemental beta-carotene improves the vitamin A status of nursing women in undeveloped countries who typically take in half as much vitamin A and carotenes as their wealthier counterparts.

--Am J Clin Nutr, 66: 52-61, 1997