Written by Jessica Patella, ND. In a 3 year study of 244 postmenopausal women, a form of vitamin K-2, menaquinone-7 (found in fermented curd cheese and fermented soybeans) had 51% decrease in low bone mass and the risk of fractures.
Osteoporosis of the hip affects over 4.5 million women over the age of 50 (5). Recent research found that a low dose of menaquinone-7, a form of vitamin K, significantly improved bone health in postmenopausal women (1).
There are different types of vitamin K; the two main types include vitamin K1 and vitamin K2. The long-chain form of vitamin K2 is known as menaquinone-7 (MK-7) and was the form recently researched (1). Menaquinone-7 is naturally found in small amounts in fermented curd cheeses and in large amounts in the Japanese food natto (fermented soybeans) (1). Lower fracture rates have been reported in Japanese regions that consume high amounts of natto (2). This information has led to further study of menaquinone-7, which has been relatively unstudied up to this point (1,2).
The recent research included 244 postmenopausal women between 55 and 65 years of age (1). The women were randomly assigned to one of two groups: the menaquinone-7 group (n=120) or the placebo group (n=124) and followed for 3-years. The women in the menaquinone-7 group took one 180 micro-gram capsule of menaquinone-7 daily, while the placebo group took one placebo pill daily (1). The women were seen at the research clinic each year of the study (1).
At the end of the three-year study, women supplementing with the menaquinone-7 daily had a 51%t decrease in uncarboxylated osteocalcin levels compared to placebo (p<0.001). High levels of uncarboxylated osteocalcin are associated with low bone mass and increased risk of fractures, therefore the decrease in the menaquinone-7 group shows improvement in bone mass and a reduced risk of fractures (3,4).
The menaquinone-7 group also had a 21% increase in carboxylated osteocalcin levels compared to placebo (p<0.001). Improvement of vitamin K status is measured by an increase in carboxylated osteocalcin levels and vitamin K is shown to improve bone health (1).
Vitamin K status of bone, determined by the uncarboxylated osteocalcin/carboxylated osteocalcin (ucOC/cOC) ratio, improved by 58% in the menaquinone-7 group. The placebo group showed no improvement, also indicating improvement in bone health by supplementing with menaquinone-7 (p<0.001) (1).
Both groups showed bone loss after the first year (measured at the femoral neck). After the first year, bone loss slowed in the menaquinone-7 group. After 3 years, menaquinone-7 beneficially affected bone health compared to placebo (p=0.011 for bone mineral content, p=0.012 for bone mineral density)
Osteoporosis can also be measured by loss of bone height in vertebrae of the spine. The height loss in the middle of the spine (T10-T12) was significantly lower in the menaquinone-7 group than placebo after 2 years (MK-7 -2.5 +/- 1.8% vs -3.1 +/- 2.2%; p=0.044) and 3 years (MK-7 -3.3 +/- 2.0% vs -4.1 +/- 2.2%; p=0.0003) (1).
In conclusion, supplementing vitamin K2 in the form of menaquinone-7 significantly improved markers of bone health over a 3-year period (1). More studies are warranted to assess the relation between vitamin K2 and reducing fractures due to osteoporosis (1). The researchers concluded that supplementing vitamin K2 in the form of menaquinone-7 would benefit bone health in postmenopausal women (1).
Source: Knapen, M. H. J., et al. “Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women.” Osteoporosis international 24.9 (2013): 2499-2507.
© International Osteoporosis Foundation and National Osteoporosis Foundation 2013
Posted April 8, 2013.
Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.
References:
- Knapen MHJ, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. 2013 Osteoporosis. doi: 10.1007/s00198-013-2325-6
- Kaneki M, 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. 2001 Nutrition 17:315–21.
- Szulc P, et al. Serum undercarboxylated osteocalcin is a marker of the risk of hip fracture: a three-year follow-up study. 1996 Bone 18:487–8.
- Apalset EM, et al. Intake of vitamin K1 and K2 and risk of hip fractures: The Hordaland Health Study. 2011 Bone 49:990–5.
- Centers for Disease Control and Prevention. Osteoporosis. Fast Stats.
