Effect of breast-feeding on concentration of nitric oxide in breast milk

Abstract

Background. The effect of breast-feeding on the concentration of nitric oxide (NO) in milk was investigated in lactating mothers. Methods. Breast milk specimens were obtained from 45 lactating women after normal delivery on postpartum days 1, 2, 3, 4 and 5. The subjects were divided into three groups: Group 1, breast-feeding only; group 2, mixed feeding (breast milk by manual expression and additional formula feeds); and group 3, formula feeding only. Milk NO concentration was measured as the sum of nitrite and nitrate using the Griess reaction. Results. The highest mean milk NO concentration was on day 4 in all groups, but the peak value in group 3 was significantly lower (P< 0.0001) than in other groups. The milk NO concentrations of group 1 were significantly greater than those of groups 2 and 3. Conclusions. We conclude that breast-feeding increases the concentration of NO in milk.