Things worth knowing about "Vitamin K2 and Bones"
Vitamin K2 is essential for bone health. It activates bone-building proteins and supports the incorporation of calcium into bone tissue.
What Is Vitamin K2 and What Role Does It Play in Bone Health?
Vitamin K2 (also known as menaquinone) is a fat-soluble vitamin that plays a central role in bone metabolism. While Vitamin K1 is primarily involved in blood clotting, Vitamin K2 acts specifically on the formation and remodeling of bone tissue. It activates key proteins that are essential for maintaining a healthy bone structure.
Mechanism of Action
The most important function of Vitamin K2 in bone is the activation of osteocalcin, a protein produced by bone-forming cells called osteoblasts. Only in its Vitamin K2-activated form can osteocalcin bind calcium and incorporate it into the bone matrix. This process increases bone density and improves the mechanical strength of the skeleton.
In addition, Vitamin K2 activates the Matrix Gla Protein (MGP), which prevents calcium from depositing in blood vessel walls and soft tissues. This gives Vitamin K2 an important protective function for cardiovascular health.
Forms of Vitamin K2
Vitamin K2 exists in several subtypes known as menaquinones:
- MK-4 (Menaquinone-4): Found mainly in animal products such as meat and eggs; has a shorter half-life in the body.
- MK-7 (Menaquinone-7): Produced mainly through fermentation and found in natto (fermented soybeans); has a longer half-life and is considered particularly bioavailable.
Dietary Sources
Vitamin K2 is naturally found in the following foods:
- Natto (fermented soybeans) – the richest natural source
- Hard and soft cheeses
- Butter and cream from grass-fed dairy
- Egg yolks
- Liver and other organ meats
- Fermented foods such as sauerkraut
Recommended Intake
The European Food Safety Authority (EFSA) has set an Adequate Intake (AI) for total Vitamin K of 70 micrograms per day for adults. Specific recommendations for Vitamin K2 alone have not yet been universally standardized, as research is still ongoing. Clinical studies on bone health have frequently used doses of 90–180 micrograms of MK-7 per day.
Deficiency Signs and Risk Groups
A lack of Vitamin K2 can have a long-term negative impact on bone health. The following groups are particularly at risk:
- People with malabsorption disorders (e.g., Crohn's disease, celiac disease)
- Individuals on long-term antibiotics or anticoagulants
- Postmenopausal women with an elevated risk of osteoporosis
- People with low intake of fermented or animal-based foods
- Older adults with reduced dietary intake
Possible signs of deficiency include:
- Increased susceptibility to bone fractures
- Declining bone density (osteopenia or osteoporosis)
- Increased calcium deposits in blood vessels
Scientific Evidence for Bone Health
Numerous clinical studies support the positive effects of Vitamin K2 on bone health:
- Regular supplementation with MK-7 has been shown to increase bone mineral density and slow the rate of bone loss.
- A combination of Vitamin K2, Vitamin D3, and calcium is considered particularly effective for bone health, as Vitamin D3 promotes calcium absorption while Vitamin K2 directs calcium to the right tissues.
- In postmenopausal women, Vitamin K2 supplementation has been associated with a reduced fracture risk and improved bone quality.
Interactions and Safety
Vitamin K2 is generally well tolerated at recommended doses. Key considerations:
- Individuals taking Vitamin K antagonists (e.g., warfarin or phenprocoumon) must consult their physician before taking Vitamin K2 supplements, as it may interfere with the medication's effect.
- Toxicity from Vitamin K2 is rarely observed at natural food levels or standard supplement doses; no established Tolerable Upper Intake Level (UL) has been defined for Vitamin K2.
- Vitamin K2 works synergistically with Vitamin D3: ideally, both should be taken together.
References
- Knapen MHJ et al. - Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 2013. DOI: 10.1007/s00198-013-2325-6
- Vermeer C - Vitamin K: the effect on health beyond coagulation – an overview. Food & Nutrition Research, 2012. DOI: 10.3402/fnr.v56i0.5329
- European Food Safety Authority (EFSA) - Dietary Reference Values for Vitamin K. EFSA Journal, 2017. DOI: 10.2903/j.efsa.2017.4780