Menaquinone

Menaquinone

Menaquinone, commonly known as Vitamin K2, is a fat-soluble vitamin that plays a crucial role in various physiological processes, including blood coagulation, bone metabolism, and cardiovascular health. It is one of the two main forms of Vitamin K, the other being phylloquinone (Vitamin K1). Menaquinone is primarily found in animal products and fermented foods, and it is also synthesized by certain bacteria in the human gut.

Structure and Types

Menaquinones are characterized by their side chain, which consists of repeating isoprenoid units. The number of these units can vary, leading to different forms of menaquinone, denoted as MK-n, where 'n' represents the number of isoprenoid units. For example, MK-4 and MK-7 are two common forms of menaquinone.

Sources

Menaquinone is found in various dietary sources, including:

• Animal Products: Liver, egg yolks, and dairy products are rich in MK-4.
• Fermented Foods: Natto, a traditional Japanese dish made from fermented soybeans, is particularly high in MK-7.
• Gut Microbiota: Certain bacteria in the human gut can synthesize menaquinone, contributing to the body's Vitamin K2 levels.

Physiological Role

Menaquinone is essential for the activation of proteins involved in:

• Blood Coagulation: It is a cofactor for the enzyme gamma-glutamyl carboxylase, which modifies certain proteins required for blood clotting.
• Bone Health: Menaquinone activates osteocalcin, a protein that binds calcium to the bone matrix, thus playing a role in bone mineralization.
• Cardiovascular Health: It helps prevent vascular calcification by activating matrix Gla-protein, which inhibits calcium deposition in blood vessels.

Health Implications

Adequate intake of menaquinone is associated with several health benefits, including:

• Reduced Risk of Osteoporosis: By promoting bone health, menaquinone may reduce the risk of fractures.
• Cardiovascular Protection: It may lower the risk of arterial calcification and coronary heart disease.

Deficiency

Vitamin K2 deficiency can lead to increased bleeding risk, weakened bones, and potential cardiovascular issues. However, deficiency is rare due to the presence of menaquinone in various foods and its synthesis by gut bacteria.

Supplementation

Menaquinone supplements are available and may be recommended for individuals at risk of deficiency or with specific health conditions. The most common forms in supplements are MK-4 and MK-7.

Research and Controversies

Ongoing research is exploring the broader health effects of menaquinone, including its potential role in cancer prevention and treatment. However, more studies are needed to fully understand its benefits and optimal intake levels.

Also see

• Vitamin K
• Phylloquinone
• Osteocalcin
• Gamma-glutamyl carboxylase
• Natto