Menaquinone-7, often referred to as MK-7, is a specific type of Vitamin K2 important for human health. It is a fat-soluble vitamin within the Vitamin K family, known for its involvement in various bodily processes. While Vitamin K is known for overall well-being, MK-7 is a distinct form of K2 with unique properties. Its presence in the diet and its functions contribute to maintaining physiological balances.
Understanding Menaquinone-7
Menaquinone-7 is a form of Vitamin K2, one of the two main natural forms of Vitamin K (the other being K1, or phylloquinone). Vitamin K2 (menaquinone or MK) encompasses several subtypes, designated as MK-n. MK-7 is a long-chain menaquinone, distinguishing it from shorter forms like MK-4.
MK-7 has superior bioavailability and a longer half-life than Vitamin K1 and other K2 forms like MK-4. After ingestion, MK-7 reaches maximal serum levels around 6 hours and remains detectable in the bloodstream for up to 72 hours, unlike MK-4 which quickly disappears. This extended presence allows MK-7 to be more effectively utilized by tissues outside the liver, such as bones and arteries.
MK-7’s longer side chain contributes to its enhanced absorption and prolonged circulation. This makes MK-7 particularly effective in delivering benefits throughout the body. While MK-4 can be synthesized from Vitamin K1, long-chain menaquinones like MK-7 are primarily produced by bacteria during fermentation. This difference in origin and metabolic fate highlights why MK-7 is an efficient form of Vitamin K2 for systemic health.
Contributions to Bone and Cardiovascular Health
Menaquinone-7 maintains bone and cardiovascular health by activating specific proteins. For bone health, MK-7 acts as a cofactor for osteocalcin carboxylation, a protein produced by osteoblasts responsible for bone formation. Once carboxylated, osteocalcin gains the ability to bind calcium ions, integrating calcium into the bone matrix. This helps build stronger bones and may reduce fracture susceptibility.
In addition to its role in osteocalcin activation, MK-7 influences bone metabolism by suppressing signaling pathways like NF-κB, involved in bone resorption. Inhibiting these pathways helps balance bone formation and breakdown, preventing age-related bone loss and conditions like osteoporosis. Studies have shown that MK-7 supplementation can enhance osteocalcin carboxylation and may reduce bone loss.
For cardiovascular health, MK-7 activates Matrix Gla Protein (MGP), a potent inhibitor of arterial calcification. MGP, like osteocalcin, requires Vitamin K-dependent carboxylation to become active. Activated MGP prevents calcium deposition in artery walls and soft tissues, maintaining arterial flexibility and blood flow. Uncarboxylated, or inactive, MGP has been linked to increased arterial calcification and stiffness.
Research indicates that MK-7 supplementation can reduce levels of inactive MGP and may inhibit the progression of cardiovascular calcification. This protective effect is particularly relevant in conditions where arterial calcification is prevalent, such as in aging populations or individuals with chronic kidney disease and diabetes. MK-7 prevents calcification partly by affecting MGP synthesis and activation in the vascular wall, increasing active MGP to inhibit ectopic calcification.
Dietary Sources and Supplementation
Menaquinone-7 is naturally present in certain foods, primarily those that have undergone fermentation by specific bacteria. The most concentrated dietary source of MK-7 is natto, a traditional Japanese fermented soybean product. Natto contains exceptionally high levels of MK-7, with approximately 90% of its K2 content being in the MK-7 form.
Other fermented foods, particularly certain cheeses, also contain varying amounts of long-chain menaquinones, including MK-7. The MK-7 content in cheeses can differ based on factors such as the type of cheese, ripening time, fat content, and the bacterial cultures used in their production. While fermented cheeses are a source of menaquinones in Western diets, the quantities may not be sufficient to achieve optimal levels for all individuals. Animal products such as chicken, beef, and some dairy products also contain moderate levels of K2, including MK-7, though generally less than natto.
For individuals who may not consume enough MK-7 through their diet, supplementation can be a consideration. Menaquinone-7 supplements are available, often derived from bacterial fermentation processes similar to those found in natto. These supplements provide a consistent and measurable intake of MK-7, which can be beneficial for supporting bone and cardiovascular health. While vitamin K is generally considered safe, those taking anticoagulant medications should consult a healthcare professional, as high doses of Vitamin K can potentially interfere with these medications.