Vitamin K2 & Healthy Bones
For decades calcium has been the go-to dietary supplement for improving bone health. However, several studies show that supplementing with calcium exclusively is not enough. The body needs to optimize the use of calcium, making sure it is directed to and utilized by the bones.
Osteoporosis is a disease characterized by loss of bone mineral density. According to the World Health Organization (WHO), osteoporosis currently affects some 200 million people globally. Worldwide, one in three men are expected to suffer from osteoporotic fractures in the future, whereas lifetime risk of fracture for women is nearly one in two. Women are more vulnerable due to two factors:
- Women in general have less bone mass than men
- The annual loss of bone mass in women accelerates after menopause.
Vitamin K2, particularly in the menaquinone-7 (MK-7) form, has been shown to help the body to optimally use calcium by binding it to bones, keeping them dense and strong, and lessening risk of fracture throughout aging.
How is Bone Affected by K2?
Bone is comprised of a hard outer shell and spongy inner tissue matrix, which is a living substance, and the entire skeleton is replaced approximately every 7 years. This process is regulated by osteoblasts (cells that build up the skeleton) and osteoclasts (cells that break down the skeleton). As long as the bone-forming activity (absorption) is greater than the bone-breakdown (resorption), the process of maintaining healthy bones is kept under control.
Osteoblasts produce a vitamin K2-dependent protein called osteocalcin, which helps bind calcium in the bone matrix, leading to increased bone mineral content. Consequently, the skeleton becomes more resistant and less susceptible to fracture. But osteocalcin needs vitamin K2 to function optimally.
In the case of long-term vitamin K2 deficiency, osteoclasts will remove more bone tissue than osteoblasts can build. This will result in a slow and steady loss of bone tissue, eventually leading to porosity, degradation, and weakness of the bones, which could lead to increased risk of fracture.
Studies Show Vitamin K2 Maintains Bone Health
Because natto (the traditional Japanese dish made of fermented soybeans) is the most abundant source of vitamin K2 as menaquinone-7 (MK-7), population-based studies have shown that in those regions in Japan where women consumed the most natto, the women generally have shown low rates of fractures. More observational studies suggest that natto may dramatically reduce risk of developing osteoporosis. Until 2012, there had only been 2, 1-year studies of K2 as MK-7 and bone status in healthy elderly. In these, the MK-7 significantly improved the “switching on” of osteocalcin to get to work (also called OC carboxylation).
Based on these studies, a 3-year study of a vitamin K2 as MK-7 ingredient on 244 women showed for the first time clinically statistically significant protection of the vertebrae and the hip (femoral neck) against osteoporosis. This was achieved with only 180 mcg daily of vitamin K2, which is considered a “nutritional dose,” meaning it is much more easily obtainable through supplementation and the right diet than pharmaceutical doses used in previous studies. The K2 group showed significantly increased circulating active osteocalcin (cOC), a well-established biomarker for bone and vitamin K status. Additionally, the inactive protein, ucOC, in the supplement group decreased with 51% +/- 21 % as compared to the placebo group (+4 % +/- 49%).
After 3 years of supplementation, improvements in both bone mineral content and bone mineral density were statistically significant in the vitamin K2 group. Further, bone strength was statistically improved, demonstrating therapeutic benefits for the K2 group as compared to the placebo group. This study appears in the January 2013 issue of Osteoporosis International, validating the credibility of the research findings.
Kaneki et al. Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk. Nutrition. 2001 Apr;17(4):315-21.
Ikeda Y et al. Intake of fermented soy- beans, natto, is associated with reduced bone loss in postmenopausal women: Japanese Population-Based Osteoporosis (JPOS) Study. J Nutr. 2006 May;136(5):1323-8.
Knpen et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013 Sep;24(9):2499-507.