Plasma, red cell, and breast milk folacin concentrations in lactating women.

Folacin concentrations (Lactobacillus casei activity) in human milk, in plasma and red blood cells, and other pertinent blood values have been studied in 91 women during the 1st yr after parturition. Iron but no folic acid supplementation was given. The women were divided into three groups according to the duration of the lactation period, group A 6-greater than 12, group B 1-less than 6 and group C less than 1 month, respectively. The women in groups A, B, and C showed no signs of folacin deficiency as judged from the plasma and red cell folacin concentrations and the peripheral red blood cell picture. The folacin concentration in human milk increased during the first 3 months after parturition. Toward the end of the lactation period the folacin concentration in human milk decreased. We conclude that in this population the folacin intake is adequate to meet the increased requirements during lactation, and folic acid supplementation is therefore not recommended as a routine during lactation. The women in group A had significantly higher red cell folacin concentrations both at parturition and 12 months later than the women in group C. The study suggests a relationship between the nutritional status of the mothers and the length of the lactation period, and provide further evidence to the hypothesis that there exist regulatory mechanisms to maintain the folacin concentrations in human milk.