What is the difference between K2 and K2mk7?
To understand the distinction, it's essential to first grasp that vitamin K2 is a classification of related fat-soluble vitamins, known as menaquinones, abbreviated as MK-n. The 'n' in MK-n represents the length of the vitamin's isoprenoid side chain, which influences how the body absorbs, utilizes, and retains the compound. Therefore, K2mk7 is not a different vitamin from K2, but rather a specific and highly effective form of it, menaquinone-7. Other notable subtypes include menaquinone-4 (MK-4), a short-chain version with different properties.
Bioavailability and Half-Life: The Primary Differentiators
One of the most significant differences lies in the bioavailability and half-life of MK-4 and MK-7. Bioavailability refers to the degree to which a substance is absorbed and available at the site of action. The half-life is the time it takes for the concentration of a substance in the body to be reduced by half.
- Absorption and Distribution: MK-4 is a short-chain menaquinone found in animal products like egg yolks and meat. It is rapidly absorbed but has a very short half-life, meaning it disappears from the bloodstream within hours. In contrast, MK-7 has a much longer half-life, allowing it to accumulate in the bloodstream and remain active for days. This allows MK-7 to be delivered effectively to tissues beyond the liver, such as the bones and arteries, providing more consistent support.
- Dosing Frequency: Due to its short half-life, MK-4 must be taken in larger, more frequent doses to maintain sufficient levels in the body, whereas a much smaller, once-daily dose of MK-7 is sufficient.
Sources of K2 Subtypes
Understanding the source of each menaquinone is also key to distinguishing between them. The two main forms come from different origins.
- MK-4: Primarily found in animal-based foods, including high-fat dairy, egg yolks, and organ meats. The body can also convert vitamin K1 from leafy greens into MK-4, but this process is often inefficient.
- MK-7: Sourced predominantly from bacteria, with the most concentrated natural source being the traditional Japanese fermented soy product, natto. Other fermented foods and certain cheeses also contain MK-7.
Comparison of K2 (MK-4) and K2mk7 (MK-7)
| Feature | Vitamin K2 (MK-4) | Vitamin K2 (MK-7) |
|---|---|---|
| Chemical Structure | Shorter isoprenoid side chain | Longer isoprenoid side chain |
| Half-Life | Very short (cleared in hours) | Long (remains active for days) |
| Bioavailability | Lower bioavailability at typical nutritional doses | Higher bioavailability, accumulates in the body |
| Dosing | Requires larger, more frequent dosing | Effective in smaller, once-daily doses |
| Primary Sources | Animal products like egg yolks and liver | Fermented foods like natto; also some cheeses |
| Metabolic Fate | Clears quickly, primarily acting in the liver | Distributed more broadly to bones, arteries, and tissues |
| Origin | Synthesized by animals from K1; also exists synthetically | Produced by bacteria during fermentation |
The Impact on Health
Both MK-4 and MK-7 contribute to critical bodily functions, mainly related to blood clotting, bone health, and cardiovascular health. However, the superior bioavailability and longer half-life of MK-7 offer distinct advantages.
- Bone Health: Vitamin K2 activates osteocalcin, a protein that directs calcium to the bones for mineralization. Clinical studies suggest MK-7 is a more effective and consistent way to support bone health due to its long-lasting presence in the bloodstream, which ensures a steady supply for osteocalcin activation.
- Cardiovascular Health: MK-7 also activates matrix Gla protein (MGP), which helps prevent calcium from depositing in arteries. This mechanism reduces the risk of arterial calcification and heart disease. Research has shown a strong correlation between higher MK-7 intake and reduced cardiovascular risk.
Choosing the Right K2 Supplement
For those considering supplementation, the form of vitamin K2 matters. While synthetic MK-4 is available, the natural, fermentation-derived MK-7 is widely regarded as the superior option due to its long half-life and potent efficacy. When selecting a supplement, look for products containing menaquinone-7 (MK-7), often derived from natto, to ensure optimal absorption and sustained health benefits, particularly for bone and cardiovascular support.
Commonly found in supplements:
- MK-7 from Natto: A popular, natural choice, often with over 99% of the highly-bioactive trans isomer.
- Synthetic MK-4: Often used in higher, multi-dosing regimens but less effective at a daily nutritional dose.
In conclusion, while K2 is the general class of vitamins, MK-7 is a specific, long-chain subtype offering superior bioavailability and health benefits. The difference between K2 and K2mk7 isn't that they are distinct vitamins, but rather that K2mk7 is the specific form that stands out for its effectiveness in supporting long-term bone and heart health. Making an informed choice about your vitamin K2 source is crucial for maximizing its benefits.
Disclaimer: Always consult with a healthcare professional before starting any new supplement regimen, especially if you take blood-thinning medication.
Visit Healthline for more information on the health benefits of Vitamin K2.
