Vitamin B6, also known as pyridoxine, is a water soluble vitamin that plays an important role as a coenzyme in the human body. A coenzyme is a molecule that binds to an enzyme allowing it to function – and pyridoxine binds to many enzymes (over 100!) that are important in energy metabolism. Good food sources of pyridoxine include fish, poultry and certain nuts. Many prenatal and multivitamin/multimineral supplements contain pyridoxine. Nursing women should consume ~2 mg of vitamin B6 per day.
For a nursing mother, pyridoxine in the diet is important because concentrations in breast milk are dependent on maternal intake. A landmark study completed in 1985 showed that as maternal pyridoxine intake increased, so did concentrations in human milk. Additionally, recent research has shown that B-vitamins in human milk can fluctuate daily based on time of day, dietary intake, and when vitamin supplements are consumed – so avoiding pyridoxine is not advised.
When it comes to breastfeeding, though, nursing mothers may need to be careful about how much they are taking (particularly in supplements). According to one study, supplemental doses of pyridoxine ranging from 0.5-4.0 mg/day had no impact on serum prolactin levels or milk supply. Similarly, another study saw no impact of a maternal 100 mg intramuscular dose of pyridoxine at term. There is some evidence that high doses of B6 (600 mg/day) can cause suppression of lactation. While the body of evidence is not robust, because B6 levels in milk are easily impacted, do not advise mothers to avoid pyridoxine. It may be appropriate for an RD to evaluate B6 intake to ensure it is less than 4 mg per day if you suspect B6 intake may be impacting milk supply.
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