Vitamin K2

What it is

Vitamin K2 is a family of fat-soluble menaquinones best known for directing calcium metabolism. It appears most often in our quotes as the partner to vitamin D3 in bone and immunity briefs. The two main supplement forms are MK-7, a long-chain menaquinone typically produced by fermentation, and the shorter-acting MK-4.

Forms and sourcing

MK-7 dominates modern briefs because its long half-life supports meaningful once-daily microgram dosing. It is available as all-trans material, the bioactive isomer that quality specifications should state explicitly, in powder, oil and microencapsulated grades. Microencapsulation matters: K2 is sensitive to alkaline minerals in compressed formats, and protected grades preserve label claim through shelf life.

Benefits and evidence

Vitamin K carries authorised EFSA health claims for the maintenance of normal bones and normal blood clotting, which apply to K2 as an approved source form. Research interest beyond the claims centres on arterial calcification and vitamin D partnership. Typical study doses for MK-7 run 45–180 µg per day.

Typical dosage and formats

Common inclusions are 45–100 µg of MK-7 per daily dose against a 75 µg NRV for vitamin K. Because doses are tiny, homogeneity in blending is the key manufacturing control. K2 works in capsules, tablets, softgels and oil-based liquids; in tablets containing calcium or magnesium oxide, specify a microencapsulated grade.

UK and EU regulatory position

Vitamin K2 (menaquinone) is a permitted source of vitamin K for food supplements in the UK and EU, and the authorised claims for normal bones and normal blood clotting may be used when the product supplies at least 15% of the NRV per daily dose. People taking anticoagulant medicines are routinely advised on-pack to consult a doctor before use, and our labelling review covers this. All-trans MK-7 specification and stability data are part of our standard supplier qualification.