Vitamin K2 Steps Into the Spotlight for Bone and Heart Health

John Watson; Reviewed by: Anya Romanowski, MS, RD

Disclosures

October 10, 2018

Remaining Questions

Supplemental K2 is now standard of care for treating osteoporosis in Japan, and has been gaining attention in Western cultures as well.[11] Although the promising results described above merit enthusiasm, important questions remain regarding its use.

Studies comparing relatively lower doses of MK-7 supplementation with placebo in early menopausal[14] and postmenopausal women[15] produced conflicting results, with the former experiencing no differences in bone loss at 1 year but the latter seeing less age-related decline in bone content and density at the femoral neck and lumbar spine at 3 years. This raises questions regarding the optimal dose range of K2 for various populations, the duration of follow-up needed to determine its effect, and whether supplements can provide nutrient levels as adequate as dietary intake.

There have been several reports of elevated risk for cardiovascular disease among older adults and postmenopausal women taking calcium supplements.[16,17,18,19,20,21] However, this link has been questioned by other recent studies,[22,23] with clinical guidelines[23,24] suggesting that any risk can be mitigated if calcium supplements are taken within tolerable ranges (eg, not above the range of 2000-2500 mg/d). As this link continues to be investigated, the possible role of K2 supplements in counterbalancing any such risk is highly worthy of a robust clinical analysis.

Certain varieties of K2 supplements, such as MK-7, have also been shown to interfere with anticoagulation therapy, whereas others like MK-4 carry no risk for hypercoagulation even at relatively high doses.[11] Physician awareness of the different properties of various K2 supplements is therefore crucial in patients taking anticoagulation therapy.

Although the evidence on K2 is preliminary and sometimes contradictory, there is nonetheless valid reason to be excited about the potential of this modest intervention. If nothing else, this collection of studies indicates that, although vitamin K remains essential, it is in no way monolithic.

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