Vitamin
B-Complex
A group of eight B vitamins that work together to support energy metabolism, nervous system function, and red blood cell production.
Moderate Evidence
Strong Evidence Vitamin
Vitamin K2
Vitamin K2 (menaquinone) is a fat-soluble vitamin that plays a critical but often overlooked role in calcium metabolism. While vitamin K1 (phylloquinone, found in leafy greens) primarily supports blood clotting, K2 activates proteins that direct calcium to appropriate destinations — specifically, osteocalcin (which deposits calcium into bones and teeth) and matrix Gla-protein (MGP, which prevents calcium from depositing in arteries and soft tissues). The most important forms are MK-4 (short-acting, found in animal products like egg yolks and butter from grass-fed animals) and MK-7 (long-acting, produced by bacterial fermentation, highest in natto — a Japanese fermented soybean dish). MK-7 has a much longer half-life (approximately 72 hours vs. 1-2 hours for MK-4), making it more practical for daily supplementation. The clinical significance of K2 has grown considerably as research reveals the "calcium paradox" — the observation that many people simultaneously have too little calcium in their bones (osteoporosis) and too much in their arteries (vascular calcification). K2 appears to resolve this paradox by ensuring calcium goes where it belongs.
Updated March 1, 2026This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication regimen.
Benefits & Uses
Activates osteocalcin for bone calcium deposition. Activates matrix Gla-protein to prevent arterial calcification. Synergistic with vitamin D3 for calcium metabolism. May reduce fracture risk. Associated with reduced cardiovascular calcification. Supports dental health.
Side Effects & Precautions
Extremely well tolerated with no known toxicity at supplemental doses. No upper limit has been established. Rarely, mild GI discomfort.
Dosage & Administration
MK-7: 100-200mcg daily. MK-4: 15-45mg daily (much higher dose required due to short half-life). Take with a fat-containing meal for absorption. Always pair with vitamin D3 for synergistic calcium metabolism. MK-7 is the preferred supplemental form for most people due to convenience and longer half-life.
Contraindications
Patients on warfarin or other vitamin K-dependent anticoagulants (K2 directly opposes their mechanism). Individuals with clotting disorders should consult their physician.
Known Interactions
| Substance | Type | Severity | Description |
|---|---|---|---|
| Warfarin (Coumadin) | major | Warfarin works by inhibiting vitamin K-dependent clotting factors. Supplemental vitamin K2 directly opposes this mechanism, potentially rendering warfarin ineffective and dramatically increasing clot risk. Patients on warfarin must NOT take K2 supplements without explicit physician approval and close INR monitoring. | |
| Other blood thinners (DOACs: rivaroxaban, apixaban) | major | While DOACs work through different mechanisms than warfarin (factor Xa or thrombin inhibition rather than vitamin K antagonism), vitamin K2 still promotes coagulation factor synthesis. The interaction is less direct than with warfarin but clinically relevant. Medical consultation required. |
Sources
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Moderate Evidence
Mineral
Magnesium Glycinate
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Strong Evidence
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This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication regimen.