Disclaimer: This information is for general knowledge and should not be taken as medical advice. Consult with a healthcare professional before starting any new supplement regimen.
What is Vitamin K2 and Why is it Important?
Vitamin K is a fat-soluble vitamin family with two primary forms: Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone). While K1 is involved primarily in blood clotting, K2 plays a more significant role in cardiovascular and bone health. Its function is to activate specific proteins that direct calcium within the body. Specifically, K2 activates Matrix Gla Protein (MGP), which prevents calcium from depositing in soft tissues like arteries, and Osteocalcin, which binds calcium to the bone matrix.
This crucial function prevents the so-called “calcium paradox,” where calcium is absorbed (often with the help of Vitamin D) but fails to be properly directed to bones, potentially leading to arterial calcification. Therefore, considering Vitamin K2 intake is especially important for those consuming Vitamin D and/or calcium supplements.
The Different Forms of Vitamin K2: MK-4 vs. MK-7
Vitamin K2 exists in several forms, known as menaquinones (MK-n), which are distinguished by the length of their side chain. The two most commonly considered forms are MK-4 and MK-7, and their differences are crucial for understanding the potential amounts to consider.
MK-4 (Menaquinone-4)
MK-4 is a short-chain form of Vitamin K2 found primarily in animal-based foods like egg yolks, butter, and organ meats from grass-fed animals. It has a very short half-life of only a few hours, meaning it is cleared from the blood relatively quickly. This short duration means that for an effect, MK-4 is often considered in higher amounts and potentially taken more frequently. For example, in Japan, where it is used for osteoporosis treatment, it is considered in milligram quantities. The MK-4 found in supplements is often synthetic, whereas the MK-4 in food is produced naturally.
MK-7 (Menaquinone-7)
MK-7 is a long-chain menaquinone, primarily sourced from fermented foods, with natto (fermented soybeans) being the richest source. It has a much longer half-life, staying in the body for up to three days, which allows for potentially less frequent intake. This higher bioavailability suggests MK-7 can be effective in lower, microgram-range considerations compared to MK-4. Studies have shown that amounts in the range of 45–180 mcg per day have been observed to be effective for activating proteins crucial for bone and cardiovascular health.
Comparison of MK-4 and MK-7
| Feature | MK-4 (Menaquinone-4) | MK-7 (Menaquinone-7) |
|---|---|---|
| Primary Source | Animal-based foods (eggs, butter, liver) | Fermented foods (natto, some cheeses) |
| Half-Life in Body | Very short (approx. 2 hours) | Long (up to 3 days) |
| Bioavailability | Lower in nutritional considerations | Higher and more stable |
| Typical Considerations | Higher amounts, often in milligram quantities per day in divided intakes in specific contexts | Lower amounts, typically in microgram quantities per day |
| Availability | Mostly synthetic in supplements | Can be natural (e.g., from natto) or synthetic |
| Potential Frequency | Multiple times per day in certain contexts | Potentially once per day |
Factors Influencing Your Vitamin K2 Needs
Understanding your need for K2 is not a one-size-fits-all decision. Several factors can influence individual requirements:
- Dietary Intake: If your diet is low in K2-rich foods (natto, grass-fed dairy, egg yolks), you may need to consider supplementation. Many Western diets are suggested to be deficient in K2.
- Age and Health Status: Older adults and individuals with concerns regarding bone density or cardiovascular health may explore K2 supplementation to support bone and arterial health. Children also have high needs during growth periods.
- Vitamin D Supplementation: Because K2 and D3 are often considered to work together to regulate calcium, adequate K2 is suggested when consuming Vitamin D to help ensure calcium is properly utilized.
- Medication Use: If you are on blood-thinning medication like warfarin, you must consult a healthcare professional before considering any K2 supplement. Changes in vitamin K intake can potentially interact with the medication's effectiveness.
- Existing Nutritional Status: Those with a suspected lower status, potentially due to poor diet or certain gut conditions, may explore higher initial amounts under medical supervision.
Understanding Typical Considerations
While there is no official Recommended Dietary Allowance (RDA) specifically for Vitamin K2, research provides general guidance.
- For General Bone and Cardiovascular Support: Many supplements contain amounts in the range of 90 to 180 micrograms (mcg) of MK-7. This range is often considered to potentially support adequate levels in healthy adults.
- For Targeted Health Support: Some studies on bone health have used amounts of 180 mcg of MK-7 daily over several years. For considerations involving MK-4, amounts are typically much higher (often 45 mg) and in specific contexts, such as in Japan.
- For Those Consuming Vitamin D: Considering a combined D3/K2 supplement is common, with K2 amounts often considered in relation to the amount of Vitamin D. A balanced approach may support effective calcium use for bone health.
Sourcing and Absorption of Vitamin K2
Your body's absorption of Vitamin K2, being a fat-soluble vitamin, is best supported when consumed with a meal containing some healthy fat.
Dietary Sources:
- Natto (fermented soybeans) is an exceptionally rich source of MK-7.
- Certain aged cheeses (e.g., Gouda, Brie) contain smaller but useful amounts of MK-7.
- Animal products like egg yolks, goose liver pate, and grass-fed butter are sources of MK-4.
Supplements:
- K2 supplements are widely available, typically containing MK-7, MK-4, or a blend of both.
- MK-7 is often preferred for its long-lasting effect, allowing for potentially once-daily considerations.
- Check labels for third-party testing to help ensure product quality and reported amounts.
Conclusion
Determining what strength K2 should I take? boils down to a few key considerations: your health goals, dietary habits, and preference for MK-7 or MK-4. For most individuals seeking daily support for bone and cardiovascular health, a supplement containing 90-180 mcg of MK-7, taken potentially once daily, is a common approach. Individuals with specific conditions, those taking blood thinners, or those considering higher amounts of MK-4 should always consult a healthcare provider for personalized guidance. As a fat-soluble vitamin, taking K2 with a meal containing healthy fats may support its absorption and benefit to your body. The relationship with Vitamin D further highlights the importance of a balanced approach to supplementation for robust health.
