Bone health is dependent on a dynamic balance between cellular activity, nutrient availability, existing structure, and signaling from genes and cellular pathways. As we age, certain lifestyle factors such as physical activity and nutritional status may influence bone integrity and overall health. Evidence suggests that some forms of vitamins D and K may contribute to bone health and healthy aging. 

Vitamin K exists in two main forms: vitamin K1, which is found in leafy green vegetables and helps support the production of coagulation factors, and vitamin K2, which is found in certain animal products, fermented dairy, and is also produced by gut microbiota. Evidence suggests that MK-4, a bioavailable form of vitamin K2, may help support healthy bone composition. MK-4 has been shown in studies to increase osteoblast production of osteocalcin and collagen type II. Additionally, MK-4 has been shown to reduce osteoblast apoptosis, suggesting it may help promote certain aspects of bone strength.

Vitamin D is a fat-soluble vitamin that is well known for supporting healthy bones through the regulation of calcium-phosphorus homeostasis and its role in bone turnover. Low vitamin D status has been associated with decreased bone density and increased fracture risk. Vitamin D deficiency or insufficiency is common, with epidemiological findings showing almost 30% of the U.S. adult population to be deficient and 40% to have insufficient status. Evidence indicates that vitamin D3 (cholecalciferol) may help raise and maintain serum 25(OH)D concentrations. 

A recently published pilot study investigated the effects of supplemental cholecalciferol and vitamin K2 on bone health in 22 healthy postmenopausal women over the age of 50. The intervention consisted of 2,000 IU (50 µg) of vitamin D3 and 37.5 µg of vitamin K2 daily for 60 days. The study evaluated protein signaling markers related to bone mineralization and formation, including three Wnt signaling inhibitors: Dickkopf-related protein (DKK)-1, DKK-2, and sclerostin (SOST). Decreased levels of DKK-2 and increased levels of DKK-1 and SOST have been associated with age-related reductions in bone mass. Of note, DKK-2 has been identified as both a Wnt antagonist and agonist and may play a particularly critical role in the maintenance of bone health.

At the study terminus, a 7.6% increase in DKK-2 was observed when compared with baseline measurements. The authors postulate that DKK-2 levels may, therefore, be dependent on the availability of vitamins D3 and K2 in the body. More research is needed, however, before clinical conclusions can be made. Placebo-controlled clinical studies with more participants and repeatable primary outcomes are needed. A thorough understanding of the role of DKK-2 and other Wnt signaling inhibitors on bone mineralization is also needed.

While more research is needed, evidence suggests that vitamins D3 and K2 may help support bone health. These fat-soluble vitamins also help support healthy aging and overall immune health.

By Dr. C. Ambrose, ND, MAT