Due to vitamin K’s role in blood coagulation, bone metabolism, and vascular health,[1][2][3] supplementation with vitamin K is claimed to have a range of benefits on blood clotting (coagulation), bone health, cardiovascular health, diabetes and blood sugar, and cancer.
The main benefit of vitamin K supplementation is in newborn babies, because vitamin K deficiency bleeding (VKDB) can arise due to inadequate vitamin K storage or a vitamin K deficiency in the mother’s breast milk.[4][5][6][7] To reduce the risk of VKDB, a single 1-milligram (mg) intramuscular injection of vitamin K is routinely administered to newborns.[4][5][6][7] In adults, there is also a relationship between the dietary intake of vitamin K and normal blood coagulation.[8]
Observational studies have found that insufficient dietary intake of vitamin K (i.e., lower than the adequate intake) and low serum concentrations of vitamin K are associated with low bone mineral density.[9][10][11] It is also generally agreed that there is a relationship between the dietary intake of vitamin K and the maintenance of normal bone health.[8] However, while meta-analyses of randomized controlled trials have found that supplementation with vitamin K can affect markers of bone health, including bone mineral density,[12] the effects on bone fracture risk are inconsistent.[13][14] Further research is needed to determine whether vitamin K can prevent or treat osteoporosis.
Low serum concentrations of vitamin K have been associated with coronary artery calcium progression, a marker of calcification and stiffening of arteries which can cause cardiovascular disease.[15] Consequently, vitamin K has been suggested to support cardiovascular health. However, while low serum concentrations of vitamin K appear to be associated with a greater cardiovascular disease risk and higher mortality,[16][17][16] the current evidence does not show a relationship between the dietary intake of vitamin K and the normal function of the cardiovascular system or cardiovascular disease mortality.[8][16] Furthermore, meta-analyses of randomized controlled trials do not support a benefit of vitamin K supplementation on cardiovascular health.[18][19][20][21]
Low serum concentrations of vitamin K have also been associated with a higher risk of type 2 diabetes,[22] but randomized controlled trials show that the effect of supplementation with vitamin K on fasting glucose and insulin resistance is trivial and highly variable.[22][23][24]
Supplementation with vitamin K might play a role in cancer therapy, but further randomized controlled trials are needed to make firm conclusions.[25]
