What Is Vitamin K, and Where Does the Confusion Come From?
Vitamin K is a group of fat-soluble vitamins essential for blood coagulation and bone metabolism. The main natural types are vitamin K1 (phylloquinone) and vitamin K2 (menaquinones). The confusion around "vitamin K27" likely stems from the naming of vitamin K2 subtypes.
Vitamin K2 includes menaquinones (MK-n), where 'n' indicates the number of isoprene units in the side chain. For example, MK-7 has seven units. The term "vitamin K27" probably mixes "vitamin K2" with the "-7" from MK-7 and is not a standard nutritional term.
The Difference Between Vitamin K1 and Vitamin K2 (Menaquinones)
Vitamin K1 and K2 have different roles and sources.
- Vitamin K1 (Phylloquinone): Found mainly in leafy greens like spinach and kale. It is absorbed mostly by the liver and is crucial for blood clotting.
- Vitamin K2 (Menaquinones): Produced by gut bacteria and found in fermented foods (like natto) and some animal products. It helps manage calcium, sending it to bones and away from soft tissues such as arteries.
Menaquinone-7 (MK-7): The Compound Behind the Name
MK-7 is a highly effective and bioavailable type of vitamin K2. Its structure gives it a longer half-life, meaning it stays active in the body longer than K1 and other K2 forms like MK-4. This allows it to work more effectively in areas outside the liver, like bones and blood vessels.
Key Functions of MK-7
- Bone Health: MK-7 activates osteocalcin, a protein that binds calcium to bones, strengthening them and potentially reducing osteoporosis risk, especially in postmenopausal women.
- Cardiovascular Health: By activating matrix Gla-protein (MGP), MK-7 helps prevent calcium buildup in arteries, keeping them flexible and supporting heart health.
- Dental Health: Activated osteocalcin also aids dental health by supporting the mineralization of dentin.
The Best Sources for Menaquinone-7 (MK-7)
MK-7 is less common in Western diets but found in foods fermented by specific bacteria.
Rich Food Sources:
- Natto: This traditional Japanese fermented soybean dish is an excellent source of MK-7.
- Sauerkraut: This fermented cabbage also contains MK-7.
- Cheeses: Some cheeses, particularly hard varieties, have varying MK-7 levels.
- Animal Products: Liver and egg yolks also contain menaquinones, including MK-7.
Comparison of Key Vitamin K Forms
Here is a comparison of common vitamin K forms:
| Feature | Vitamin K1 (Phylloquinone) | Vitamin K2 (MK-4) | Vitamin K2 (MK-7) |
|---|---|---|---|
| Primary Sources | Leafy green vegetables | Meat, eggs, high-fat dairy | Fermented foods (natto), hard cheeses, supplements |
| Absorption | Poorly absorbed from plants, stored mainly in liver | Present in some animal foods | Highly bioavailable and well-absorbed |
| Half-Life | Short | Short | Longest (around 3 days) |
| Primary Role | Blood clotting in liver | Some bone and vascular functions | Extra-hepatic functions (bone mineralization, arterial health) |
Conclusion
In conclusion, "vitamin K27" is not a real vitamin name but almost certainly refers to Menaquinone-7 (MK-7), a potent form of vitamin K2. MK-7 stands out from K1 and other K2 forms due to its longer half-life and better distribution to tissues beyond the liver. It's vital for activating proteins that ensure calcium goes to bones for strength and stays out of arteries, supporting both skeletal and cardiovascular health. Consuming foods like natto or taking supplements are effective ways to get MK-7.
Research continues to explore MK-7's health effects. Consult a healthcare professional before supplementing, especially if you take blood thinners.
Why Your Body Needs MK-7
Getting enough MK-7 is important for:
- Optimizing Calcium: Directs calcium to bones and teeth instead of soft tissues.
- Cardiovascular Risk: Helps keep blood vessels flexible by preventing arterial calcification.
- Bone Strength: Improves bone mineral density, reducing fracture risk, particularly for older adults.
- Enhanced Bioavailability: MK-7's long half-life ensures sustained activity in the body.
Focusing on sources like fermented foods and supplements helps ensure adequate intake of the nutrient likely meant by "vitamin K27".
Is Taking Vitamin K2 Safe? (Note on Drug Interactions)
Vitamin K is generally safe, but those on blood thinners like warfarin must consult a doctor before supplementing. Vitamin K affects clotting, and intake changes can interfere with these medications. Consistent dietary intake is less likely to cause issues.
The Discovery of Vitamin K
Vitamin K was discovered in 1929 by Henrik Dam and identified as an antihemorrhagic factor. Its name comes from "Koagulations vitamin". Edward Adelbert Doisy helped determine its structure in the 1930s, leading to a joint Nobel Prize in 1943. Its role as a coenzyme for protein activation was understood later.
How Your Body Utilizes Vitamin K
After eating, K1 and K2 are absorbed with fat. K1 goes mainly to the liver for clotting, while K2 (like MK-7) spreads better to other tissues. Vitamin K is recycled and helps activate specific proteins. These activated proteins, containing Gla residues, bind calcium and perform functions like bone mineralization and preventing tissue calcification.
Can I get enough MK-7 from my diet?
A balanced diet usually provides enough vitamin K for blood clotting. However, many Western diets are low in MK-7, especially without regular intake of foods like natto. This can mean not enough MK-7 to activate proteins needed for optimal bone and heart health. Supplements are a good option if dietary sources are insufficient.
