Menatetrenone (MK4) is one of the nine forms of vitamin K₂.

Vitamin K₂ (MK4) and bone health

In contrast, MK4 has been shown in numerous studies to reduce fracture risk, stop and reverse bone loss. In Japan, MK4 in the dose of 45 mg daily is recognized as a treatment for osteoporosis^[91][94] under the trade name Glakay.^[95] MK4 has been shown to decrease fractures up to 87%.^[15] In the amount of 45 mg daily MK4 has been approved by the Ministry of Health in Japan since 1995 for the prevention and treatment of osteoporosis.^[16]

MK4 (but not MK7 or vitamin K₁) prevented bone loss and/or fractures in the following circumstances:

• caused by corticosteroids (e.g., prednisone, dexamethasone, prednisolone)^{[17][18][19][20]}
• anorexia nervosa^[21]
• cirrhosis of the liver^[22]
• postmenopausal osteoporosis^{[16][23][24][25][26][27]}
• disuse from stroke^[28]
• Alzheimer's disease^[29]
• Parkinson disease^[30]
• primary biliary cirrhosis^[31]
• leuprolide treatment (for prostate cancer).^[32]

Vitamin K₂ (MK7) and bone health

Menaquinone-7 (MK7), which is abundant in fermented soybeans (natto), has been demonstrated to stimulate osteoblastic bone formation and to inhibit osteoclastic bone resorption.^[96] In another study, use of MK-7 caused significant elevations of serum Y-carboxylated osteocalcin concentration, a biomarker of bone formation. MK-7 also completely inhibited a decrease in the calcium content of bone tissue by inhibiting the bone-resorbing factors parathyroid hormone and prostaglandin E₂.^[97] On 19 February 2011, HSA (Singapore) approved a health supplement that contains vitamin K₂ (MK7) and vitamin D₃ for increasing bone mineral density.^[98]