Nutritionally Relevant Supplementation of Vitamin B₆ in Lactating Women: Effect on Plasma Prolactin

Pharmacologic doses of vitamin B₆ administered to lactating women have been reported to suppress plasma prolactin. As a result, some physicians have recommended restriction of vitamin B₆ intake for lactating women. In the present investigation, 20 lactating women were given supplemental doses of vitamin B₆, 0.5 to 4.0 mg/d, beginning 24 hours after delivery. Plasma prolactin, plasma pyridoxal phosphate, and breast milk total vitamin B₆ concentrations were determined during the first 9 months postpartum. Women receiving the supplement of 4.0 mg compared with 0.5 mg of vitamin B₆ per day had significantly higher plasma pyridoxal phosphate (P < .01) and breast milk total vitamin B₆ concentrations (P < .05) beginning at 1 month postpartum and continuing through the duration of the study. Plasma prolactin concentrations were not significantly different between the two groups. The percentage of all women, regardless of treatment, in whom lactation persisted at 1 and 2 weeks and 1, 3, 6, and 9 months were 100%, 100%, 100%, 90%, 80%, and 65%, respectively. All women who ceased to lactate during the study reported doing so by choice. Nutritionally relevant doses of vitamin B₆ elevated plasma pyridoxal phosphate and breast milk total vitamin B₆ concentrations of lactating women without reducing plasma prolactin concentration or halting lactation.