Research has shown that women who are dieting and exercising tend to produce breast milk lower in certain nutrients, such as vitamin B6, that are important for babies' development. New research shows that taking a daily vitamin supplement can correct the problem, according to a study published in Medicine and Science in Sports and Exercise. Women in the study who were dieting plus taking the supplement lost 1 pound per week. They all maintained adequate levels of B6 in their milk, even though some who supplemented sporadically had lower than recommended amounts of B6 in their own blood. Getting the recommended daily amount of vitamins and minerals is important at any time in life. This becomes even more important during breastfeeding -- both for the baby and for the mother who enriches her milk for her child.