Vitamin K2

Definition

Vitamin K2, also known as menaquinone, is a fat-soluble vitamin produced by bacterial fermentation in the gut and found in fermented foods and animal products. It plays a distinct role in calcium regulation and cardiovascular health compared to vitamin K1.

How it works

Vitamin K2 exists in multiple forms (MK-4 through MK-13) depending on the bacterial strain or food source that produces it. Unlike vitamin K1, which is primarily involved in blood coagulation, vitamin K2 activates osteocalcin and matrix Gla protein, which are essential for directing calcium to bones and teeth while preventing arterial calcification. The human gut microbiome can synthesize some vitamin K2, but the amounts are often insufficient for optimal health. Fermented foods like natto, sauerkraut, and aged cheeses provide significant amounts, while animal products like grass-fed dairy and pastured eggs contain vitamin K2, particularly the MK-4 form.

Role

Vitamin K2 activates bone-building proteins and regulates calcium deposition in bones while preventing vascular calcification.

Examples

• Natto (fermented soybeans)
• Aged cheeses
• Grass-fed butter and ghee
• Sauerkraut and fermented vegetables
• Pastured egg yolks
• Fermented dairy products

Recommendations

Include fermented foods in your diet regularly, particularly natto or other naturally fermented vegetables, as they are the richest sources of vitamin K2. If fermented foods are not accessible, consider consuming grass-fed dairy products and pastured eggs, which provide moderate amounts of vitamin K2.

Key takeaway

Vitamin K2 is a specialized form of vitamin K that directs calcium to bones and away from arteries, making it vital for skeletal and cardiovascular health.

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