Understanding Vitamin K2: More Than Just K1
Vitamin K is a fat-soluble vitamin crucial for blood clotting, existing as K1 (phylloquinone) and K2 (menaquinone). K1 is found in leafy greens and primarily functions in coagulation, while K2 plays a distinct role in extra-hepatic tissues like bones and blood vessels. K2 helps direct calcium to bones and teeth, preventing buildup in arteries. K2 is found in fermented foods and animal products.
Dosage Recommendations for Vitamin K2
No official RDA exists for vitamin K2, so dosage is based on research. Optimal intake varies by age, diet, and health, and consulting a healthcare professional is advised, especially for therapeutic use.
General Health and Wellness
For healthy adults, a daily intake of 100 to 300 micrograms (mcg) is often suggested. Many supplements for general health contain 100-200 mcg.
Targeted Benefits for Bone and Cardiovascular Health
Higher doses have been used in research for bone density and cardiovascular health.
- Studies showing significant benefits often use around 180 to 200 mcg daily of MK-7.
- In Japan, 45 mg of MK-4 is used therapeutically for osteoporosis under medical supervision.
MK-4 vs. MK-7: Navigating the Forms of Vitamin K2
MK-4 and MK-7 are common forms of K2 found in foods and supplements, differing in half-life and sources.
Comparison Table: MK-4 vs. MK-7
| Feature | Menaquinone-4 (MK-4) | Menaquinone-7 (MK-7) |
|---|---|---|
| Primary Source | Animal products (egg yolk, butter, organ meats) | Fermented foods (natto, certain cheeses) |
| Half-Life | Short; hours to be cleared from the body | Long; stays in circulation for several days |
| Bioavailability | Lower, quickly cleared | Higher, better sustained blood levels |
| Supplement Dosage | Often very high (milligrams) due to short half-life | Lower (micrograms), once-daily dosing is effective |
| Supplement Origin | Often synthetic in OTC products | Often sourced naturally from fermentation |
MK-7's longer half-life makes it a popular supplement choice.
The Critical Synergy with Vitamin D3
Vitamin K2 and vitamin D3 work together. D3 increases calcium absorption, and K2 activates proteins to ensure calcium is deposited in bones and teeth, not arteries. Combining D3 with K2 is recommended for optimal calcium management, especially with higher D3 doses.
How to Get Your Vitamin K2: Food Sources vs. Supplements
Diet is preferred, but K2-rich foods are not common in Western diets.
Food Sources
- Natto: Richest source of MK-7.
- Cheese: Hard and soft fermented cheeses provide various menaquinones.
- Animal Products: Egg yolks, grass-fed butter, and organ meats contain MK-4.
- Sauerkraut: Contains smaller amounts of K2.
Supplementation
Supplements, particularly MK-7, offer a reliable way to ensure consistent K2 intake, especially for those who don't eat K2-rich foods or need specific doses. Take with fat for better absorption.
Safety and Precautions: Who Should Be Careful?
K2 is generally safe with no known toxicity. However, consult a doctor if:
- Taking Blood Thinners (Warfarin): K2 affects clotting and can interfere with these medications.
- Have Specific Conditions: G6PD deficiency, kidney disease, or bleeding disorders require medical advice before supplementing.
Conclusion
Determining how much vitamin K2 should you get lacks an official RDA. Suggested daily intake for general health is 100-300 mcg, often as MK-7. For bone or cardiovascular health, 180-200 mcg or more has shown effects in studies. Diet can provide K2, but supplements are often needed for consistent intake. Always discuss your personal needs with a healthcare provider, particularly if on blood thinners or having other health conditions.
