As women navigate midlife and menopause, supporting bone and vascular health becomes increasingly important. While calcium and vitamin D3 are often discussed, the role of vitamin K2 in this process is gaining attention.
Vitamin K2, particularly the menaquinone-7 (MK-7) form, is recognized for its potential involvement in calcium metabolism, helping to direct calcium where it’s most beneficial.
The Two Faces of Vitamin K: K1 and K2
Vitamin K is a group of fat-soluble vitamins essential for various bodily functions. Historically, vitamin K1 (phylloquinone) was primarily known for its role in blood clotting [1]. However, research has highlighted the distinct functions of vitamin K2 (menaquinones), particularly in bone and cardiovascular health.
Menaquinones, or vitamin K2, are found in fermented foods like natto and certain animal products. Among the different forms of K2, menaquinone-7 (MK-7) is often studied due to its longer half-life in the body, which may contribute to its effectiveness [2].
Vitamin K2’s Role in Calcium Guidance
One of the key functions attributed to vitamin K2 is its involvement in calcium regulation. It does this by activating specific proteins that help manage calcium distribution in the body. These proteins include osteocalcin, found in bone, and matrix Gla protein (MGP), found in soft tissues like arteries [2].
Osteocalcin is a protein produced by bone-forming cells. For osteocalcin to effectively bind calcium and integrate it into bone mineral, it needs to be activated through a process called carboxylation, which is dependent on vitamin K2 [3]. Studies have shown that vitamin K2 supplementation can enhance osteocalcin carboxylation [3][4].
Similarly, matrix Gla protein (MGP) is a potent inhibitor of calcium deposition in soft tissues, including the arteries. Vitamin K2 is essential for the activation of MGP, helping it to bind to and remove calcium from areas where it shouldn’t accumulate [2].
Supporting Bone Health with Vitamin K2
Maintaining bone density is a significant concern for women in midlife and beyond, especially during and after menopause. By activating osteocalcin, vitamin K2 helps support the incorporation of calcium into the bone matrix, contributing to bone mineralization [2].
Research suggests that vitamin K2 may play a role in supporting bone health. For instance, a three-year study found that low-dose menaquinone-7 supplementation helped decrease bone loss in healthy postmenopausal women [5]. Additionally, habitual intake of natto, a rich source of MK-7, has been associated with enhanced osteocalcin carboxylation and support for bone density [6].
Helping to Keep Arteries Flexible
Beyond bone health, vitamin K2 is also recognized for its potential to support vascular well-being. The accumulation of calcium in arterial walls can contribute to arterial stiffness, which is a factor in cardiovascular health. By activating MGP, vitamin K2 helps to discourage calcium from depositing in arteries [2].
Ongoing research, such as the InterVitaminK trial, is investigating the effects of vitamin K (menaquinone-7) supplementation on cardiovascular, metabolic, and bone health in a population-based setting [7]. Early findings from other studies have explored the effects of menaquinone-7 supplementation on vascular stiffness in post-menopausal women [8].
Working Synergistically with Vitamin D3
Vitamin D3 is well-known for its role in calcium absorption from the gut. However, once calcium is absorbed, it needs to be effectively utilized and directed within the body. This is where vitamin K2 may complement the actions of vitamin D3 [2].
While vitamin D3 supports the production of osteocalcin and MGP, vitamin K2 is responsible for activating these proteins, ensuring they can perform their intended functions of guiding calcium to bones and away from arteries. This complementary relationship highlights why these two nutrients are often considered together for comprehensive bone and vascular support.
References
- Vitamin K: an old vitamin in a new perspective. Dermato-endocrinology, 2014
- Molecular Pathways and Roles for Vitamin K2-7 as a Health-Beneficial Nutraceutical: Challenges and Opportunities. Frontiers in pharmacology, 2022
- Olive oil supplemented with menaquinone-7 significantly affects osteocalcin carboxylation. The British journal of nutrition, 2011
- The effect of menaquinone-7 (vitamin K2) supplementation on osteocalcin carboxylation in healthy prepubertal children. The British journal of nutrition, 2009
- Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2013
- Habitual natto intake elevates serum MK-7 levels, enhances osteocalcin carboxylation, and supports bone density: a meta-analysis of Japanese evidence. Frontiers in nutrition, 2025
- Study protocol of the InterVitaminK trial: a Danish population-based randomised double-blinded placebo-controlled trial of the effects of vitamin K (menaquinone-7) supplementation on cardiovascular, metabolic and bone health. BMJ open, 2023
- Effects of One-Year Menaquinone-7 Supplementation on Vascular Stiffness and Blood Pressure in Post-Menopausal Women. Nutrients, 2025
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