Is Vitamin B 6 safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Vitamin B 6. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Twenty postpartum women were randomized to receive pyridoxine 2 mg or 27 mg once daily for 28 days beginning in the first postpartum week. One-half of the infants in the 2 mg maternal supplement group were given a daily multivitamin containing 0.4 mg pyridoxine, presumably started when breastfeeding was established, although this was not stated. Maternal dietary intakes of vitamin B 6 during the study period were similar between the two groups. Weekly changes in weight and length Z scores were correlated with infant pyridoxine intake. Increases in weight and length Z scores over the course of the 28-day study period were similar between the directly supplemented infants and infants of mothers supplemented with 27 mg, and both were greater than nonsupplemented infants of mothers supplemented with 2 mg. However, these differences were clinically unimportant.[ 9 ] Seventeen postpartum lactating women were given either a 2.5 mg or 15 mg daily pyridoxine supplement beginning on the day of hospital discharge and continued for 6 months, during which time their infants were exclusively breastfed. Prior to entering the study, all maternal participants had been taking routine prenatal vitamins containing vitamin B 6 and had normal vitamin B 6 status at baseline. In 15 of the infants, weight and length were measured at birth, and again at 1, 4, and 6 months postpartum. Both were similar between the two groups at all time points.[ 22 ] Forty-four term, healthy infants in Finland were prospectively followed for growth and vitamin B 6 status beginning at birth and continuing through the first 12 months postpartum. All mothers followed World Health Organization guidelines at the time which involved exclusive breastfeeding for 6 months after birth, introducing supplemental solid foods at 6 months, and waiting to wean from breastfeeding until 9 months. At 12 months all the infants were still partly breastfed. All mothers were given a 1 mg pyridoxine supplement to take once daily beg
Effects on milk supply
A systematic review found that two studies in the 1970s using very high maternal doses of 600 mg of pyridoxine daily in divided doses three times a day for 7 days begun shortly after delivery was effective at inhibiting lactation. However, these results have not been replicated in multiple other studies, nor has very high dose pyridoxine been demonstrated to reduce prolactin levels.[ 30 ] A second systematic review found dopaminergic agents to be superior to pyridoxine in suppressing postpartum lactation.[ 31 ] A randomized, prospective, but nonmasked study compared cabergoline 1 mg (in one dose or 0.25 mg twice daily for 2 days; n = 45) to pyridoxine 200 mg 3 times daily for 7 days (n = 43) in suppressing lactation in postpartum women who did not wish to breastfeed. Treatment was initiated approximately 24 hours after delivery. Based on patient self-assessment, cabergoline was more effective than pyridoxine for suppressing lactation (78% vs 35%) and in reducing engorgement and pain (89% vs 67%) at day 7. The frequency of milk leakage was lower with cabergoline group after 7 and 14 days compared to pyridoxine (9% vs 42% and 11% vs 31%, , respectively). Headache and constipation were the most commonly reported adverse effects, occurring more frequently in cabergoline patients (15% vs 2%).[ 32 ]
Levels in milk
Vitamin B 6 refers to six similar natural isomers or vitamers: pyridoxine, pyridoxamine, pyridoxal, and each of their 5 -phosphorylated forms. After ingestion, the non-phosphorylated forms are absorbed well from the gastrointestinal tract. Each B 6 vitamer can be enzymatically converted to the active form, pyridoxal 5 -phosphate.[ 5 , 6 ] Pyridoxal and pyridoxal 5 -phosphate account for approximately 70% and 15%, respectively, of vitamin B 6 in human milk. Pyridoxine, pyridoxamine and their 5 -phosphate analogs are nearly evenly distributed among the remaining 15%.[ 7 - 10 ] Pyridoxine is the vitamer most often used medicinally and in multivitamin supplements because it is the most chemically stable. Maternal Levels. Average total vitamin B 6 concentrations are 800 to 1200 nmoL/L (140 to 200 mcg/L) in mature milk at 2 to 6 months postpartum among healthy mothers with adequate dietary intake and biochemical status not taking a B 6 supplement.[ 8 , 10 , 11 ] Maternal B 6 dietary intake and biochemical status positively influence milk levels.[ 12 , 13 ] Mothers with inadequate B 6 intake or low status have reported average total B 6 levels of 300 to 400 nmoL/L (50 to 70 mcg/L) in mature milk.[ 3 , 8 ] Low vitamin B 6 status is defined biochemically as a blood plasma pyridoxal 5 -phosphate (PLP) level 20 nmoL/L ( 5 mcg/L). Milk levels increase after birth with each stage of lactation. Reported colostrum levels are approximately 2-to-5-fold lower compared to after two weeks postpartum. Levels plateau by 2 to 6 months postpartum and thereafter gradually decline.[ 13 - 16 ] Foremilk and hindmilk levels are believed to be similar, although this has only been evaluated in two study subjects.[ 17 ] Two studies have reported 50% lower average levels in milk from mothers after preterm birth compared to those giving birth at term gestation, although underlying maternal B 6 status was not evaluated.[ 14 , 15 ] Low daily maternal doses of 2 to 4 mg pyridoxine supplementation resul
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.