Vitamin K2, a fat-soluble vitamin, plays a role in various bodily processes. It is part of the broader vitamin K family, which includes several compounds sharing a common chemical structure. While less recognized than some other vitamins, K2 contributes to fundamental physiological activities and helps maintain the body’s internal balance.
Understanding Vitamin K2
Vitamin K exists in several forms, with the two most common being Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinones). Vitamin K1 is primarily found in plants, particularly leafy green vegetables, and is involved in blood clotting. In contrast, Vitamin K2 encompasses a series of related compounds known as menaquinones, abbreviated as MK-n, where ‘n’ denotes the number of isoprene units in their side chain.
The two most studied forms of Vitamin K2 are menaquinone-4 (MK-4) and menaquinone-7 (MK-7). MK-4 is found in animal products and can also be synthesized in human and animal tissues from Vitamin K1. Its shorter side chain leads to quicker absorption and metabolism. MK-7, a longer-chain menaquinone, is predominantly produced by bacteria through fermentation. It exhibits a longer half-life in the bloodstream, allowing it to remain in the body for an extended period.
Its Core Functions in the Body
Vitamin K2’s primary action involves activating specific proteins that guide calcium within the body. This activation process, known as gamma-carboxylation, is necessary for these proteins to function effectively. Without sufficient Vitamin K2, these proteins remain inactive, impacting calcium’s proper distribution. This mechanism contributes to bone and cardiovascular health.
In bone health, Vitamin K2 activates osteocalcin, a protein produced by bone-building cells called osteoblasts. Once activated, osteocalcin binds to calcium, facilitating its integration into the bone matrix. This process supports bone mineralization and density.
Regarding cardiovascular health, Vitamin K2 activates Matrix Gla Protein (MGP). MGP is produced by vascular smooth muscle cells and inhibits calcium deposition in soft tissues, including arteries. By ensuring MGP is active, Vitamin K2 helps prevent calcium from accumulating in arterial walls, supporting arterial flexibility and vascular integrity. This role helps prevent undesirable calcification in soft tissues.
Natural Dietary Sources
Vitamin K2 is found in various foods, with its different forms, MK-4 and MK-7, originating from distinct sources. MK-4 is primarily present in animal products. Foods rich in MK-4 include organ meats like liver, fatty meats such as pork and beef, and full-fat dairy products from grass-fed animals. Egg yolks, particularly from pasture-raised hens, also provide a source of MK-4.
MK-7, on the other hand, is abundantly found in fermented foods. The most concentrated dietary source of MK-7 is natto, a traditional Japanese dish made from fermented soybeans. Certain cheeses, especially aged varieties like Gouda, Brie, and some cheddars, also contain varying amounts of MK-7 and other long-chain menaquinones (MK-8, MK-9). While some fermented vegetables like sauerkraut can contain MK-7, amounts can vary.
Why Vitamin K2 Matters
Adequate Vitamin K2 intake holds significance for long-term health, particularly concerning the skeletal and cardiovascular systems. Its role in activating specific proteins helps manage calcium’s placement in the body. This action supports strong bones by directing calcium to the bone matrix, while deterring calcium buildup in arterial walls.
The continuous presence of active Vitamin K2-dependent proteins helps preserve bone structure and arterial elasticity throughout life. This addresses a phenomenon where calcium may be deficient in bones while accumulating in soft tissues, sometimes referred to as the “calcium paradox.” Ensuring sufficient Vitamin K2 intake supports the body’s natural processes for proper calcium utilization, contributing to overall well-being.