Objective: The relationship between antioxidant (pro-)vitamin content of breast milk and diet of pregnant women has been reported. However, the assessment of a complete and reliable antioxidant index, such as the total antioxidant capacity, has never been performed in human milk.
Methods: In the present study, the total antioxidant capacity of colostrum, and transitional and mature milk was determined by the oxygen radical absorbance capacity (ORAC) assay in 29 lactating women and correlated with their food consumption assessed by dietary history during pregnancy and lactation. In addition, the total antioxidant capacity of 12 infant formulas commonly used in Italy was determined by the same method.
Results: Mean ORAC values of mature milk (1.01 +/- 0.37 mmol/l trolox eq.) were slightly lower than those of colostrum and transitional milk (1.17 +/- 0.50 and 1.18 +/- 0.38 mmol/l trolox eq., respectively). Correlations were observed between antioxidant (pro-)vitamin intakes during pregnancy (third trimester) and ORAC values of colostrum and transitional milk (both p < 0.05), but not with ORAC values of mature milk. Correlations were also found between antioxidant (pro-)vitamin intakes during lactation and transitional and mature milk ORAC values (both p < 0.05). Term infant formulas (n = 5) showed a total antioxidant capacity of 1.40 +/- 0.23 mmol/l trolox eq., whereas the antioxidant capacity of other formulas (n = 7) oscillated from 1.27 to 2.52 mmol/l trolox eq.
Conclusions: The total antioxidant capacity of breast milk in lactating women was related to a diet in which the food content of antioxidant compounds was inadequate. Efforts should be made to improve women's dietary habits during pregnancy and lactation, in order to optimize the total antioxidant capacity of breast milk.