Is Vitamin K safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Vitamin K. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Exclusive breastfeeding and failure to give infants a dose of prophylactic vitamin K at birth resulted in the death of 3 otherwise normal, consecutive male siblings from intracranial hemorrhage. A fourth male sibling was examined at 17 days of age and found to have abnormal clotting parameters. The infant and parents were found to have no genetic conditions that could account for the abnormal clotting. Within 24 hours, the infant s clotting profile normalized after 1 mg of vitamin K injection.[ 3 ]
Effects on milk supply
Exclusive breastfeeding results in inadequate milk vitamin K levels. Failure to give infants a dose of prophylactic vitamin K at birth can result in intracranial bleeding, intra-abdominal bleeding, and death.[ 5 ]
Levels in milk
Maternal Levels. Vitamin K is naturally present in human milk in concentrations of 1 to 9 mcg/L (2.2 to 20 nmol/L).[ 6 , 7 ] Similar levels have been reported in colostrum.[ 6 ] Levels are approximately 1 mcg/L higher in hindmilk than foremilk.[ 8 ] Vitamin K 1 (phylloquinone) is the predominant form in plasma and milk and derives from maternal dietary plant sources. Vitamin K 2 (menaquinones) are also present in milk, mainly as menatetrenone (menaquninone-4; MK-4), at approximately one-half the levels of vitamin K 1 .[ 7 , 9 ] Since MK-4 can be synthesized from phylloquinone in the mother, dietary phylloquinone is the main source of milk MK-4.[ 9 ] It can also be derived from maternal dietary poultry in countries where vitamin K3 (menadione), a chemical precursor of MK-4, is used in poultry feed.[ 10 ] Other menaquinones are synthesized by some bacteria. Their milk levels can be increased in mothers who consume certain fermented foods.[ 7 ] Relevant published information regarding vitamin K milk levels in mothers taking MK-4 supplements was not found as of the revision date. Four lactating mothers were given 0.1, 0.5, 1, or 3 mg single doses of oral vitamin K 1 . Milk was sampled at baseline and then at random times over 2 days after administration in 3 of the mothers and at fixed 6-hour intervals over 1 day in the fourth mother. Baseline milk levels were 2 to 3 mcg/L. Peak milk vitamin K 1 levels occurred at 12 to 24 hours after administration in all subjects. The highest level reported was approximately 150 mcg/L, occurring 18 hours after a 3 mg dose. Menaquinone levels were not measured.[ 8 ] Eleven lactating mothers between 2 and 6 months postpartum were given a single oral 20 mg vitamin K 1 supplement and their milk was collected at 0, 12, 24, 48, 96 hours, and 1 week after administration. The average peak milk vitamin K 1 level was approximately 130 mcg/L at 12 hours after administration compared to 1.1 mcg/L at baseline. By 48 hours the average milk level ha
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.