Vitamin K

Vitamin K is a group of essential fat-soluble vitamins that play a critical role in blood coagulation, bone metabolism, and cardiovascular health. It primarily exists in two natural forms: Vitamin K1 (phylloquinone), which is synthesized by plants and found in green leafy vegetables, and Vitamin K2 (menaquinones), which is produced by bacteria and found in fermented foods like natto, certain cheeses, and animal products. Vitamin K2 is further categorized into subtypes, with MK-4 and MK-7 being the most common in supplements.

Vitamin K acts as a vital coenzyme for the enzyme gamma-glutamyl carboxylase. This enzyme is responsible for the carboxylation of specific glutamic acid residues in proteins known as 'Gla-proteins,' allowing them to bind calcium ions. In the liver, this process activates clotting factors essential for coagulation. In the skeleton, it activates osteocalcin, which incorporates calcium into the bone matrix. In the vascular system, it activates Matrix Gla Protein (MGP), which prevents calcium from depositing in the arterial walls, thereby inhibiting vascular calcification.

Based on current research, the following guidelines are recommended

• Prefer Vitamin K2 (MK-7): For bone and cardiovascular support, choose the MK-7 form of Vitamin K2. It has a significantly longer half-life (up to 48 hours) compared to K1 or MK-4, allowing for once-daily microgram-level dosing (typically 90-180 mcg)
• Take with Dietary Fat: As a fat-soluble nutrient, Vitamin K must be consumed with a meal containing healthy fats to ensure optimal absorption
• Synergy with Vitamin D3: Vitamin K should ideally be taken alongside Vitamin D3; while D3 increases calcium absorption, K2 ensures that calcium is directed to the bones and away from the arteries
• Consistency is Key: For those on Vitamin K antagonist blood thinners (like Warfarin), maintain a consistent intake of Vitamin K and consult a physician before starting any supplement, as even low doses (10-20 mcg) of MK-7 can disrupt INR levels.