Protein, vitamin B6 and pyridoxine-glucoside relationships in infant nutrition during the first 6 months of age

Jeong Yeon Cho, Purdue University

Abstract

Breast milk has been recommended as the preferred source of nutrients for infants, during the first 4 to 6 months of age. In this study intakes of protein, vitamin B-6 and $\beta$-glucoside conjugates from human milk and supplementary foods during the first 6 months were examined relative to infant growth. Mean and SD of protein concentration of breast milk, measured monthly during the first 6 months by the Lowry method, were 1.31 $\pm$ 0.13 g/dl. The value at 1 month (1.55 $\pm$ 0.04 g/dl) was significantly higher than those for other months. Mean protein intakes over the first 6 months were similar for breastfed (BF) and breastfed supplemented (BFS) infants and were highly correlated with milk intake (r = 0.85). Even though protein intakes of both groups were less than the current RDA, weight-for-age and length-for-age of more than 70% of the infants exceeded the 50th percentile reference. Mothers were supplemented with four levels of vitamin B-6: 2.5, 5.0, 7.5, and 10 mg PN$\cdot$HCl/day during the first 6 months of lactation. Throughout the study, mean vitamin B-6 levels in milk, analyzed monthly by a microbiological method, were lower for the 2.5 mg group than for other groups; levels reached maximum 3-4 hr after supplements were ingested. Mean vitamin B-6 intakes of infants were significantly correlated with maternal intakes. During the first 3 months, most infants (94%) did not meet the recommended vitamin B-6 intake of 0.3 mg/day. However, infant growth was within the normal range and was similar among all groups throughout 6 months. B-6 vitamers and PN-glucoside levels in milk were determined by reverse-phase HPLC in supplemented (2.5 or 10 mg PN$\cdot$HCl/day) American women and unsupplemented Egyptian women. Pyridoxal level was highest among all vitamers in milk of each group, representing 72 and 76% for 2.5 and 10 mg groups, respectively, and 59% for Egyptian women. Mean PN-glucoside levels in milk of Egyptian women were significantly higher (11%) than for American women (1%). In Egyptian women, increased plant protein intake, in contrast to increased animal protein intake, was associated with lower vitamin B-6 concentration in breast milk.

Degree

Ph.D.

Advisors

Kirksey, Purdue University.

Subject Area

Nutrition

COinS