If bone health is your priority, the most claim-solid supplement isn't collagen or turmeric — it's the vitamin pairing of D3 and K2. This guide explains why these two vitamins are combined, what each genuinely contributes, and how to choose.
For transparency: vitamin D and vitamin K both carry authorised claims for contributing to the maintenance of normal bones. That's the firm, evidence-based basis for this article — not a claim to prevent or treat osteoporosis or any bone disease, which would be a matter for your GP.
Why D3 and K2 are paired
The two vitamins have complementary roles in normal bone maintenance, which is why combining them makes sense:
- Vitamin D3 contributes to normal blood calcium levels and the maintenance of normal bones — it's central to how the body handles calcium.
- Vitamin K2 contributes to the maintenance of normal bones — via a different pathway involving the proteins that bind calcium into bone.
Both carry authorised bone claims, and they act through different mechanisms — so a combined supplement covers the bone-maintenance angle from two complementary directions. That's the rationale behind our Vitamin D3 + K2.
Why MK-7 specifically
Vitamin K2 comes in different forms; the one used in quality supplements is MK-7 (menaquinone-7), valued for being well-absorbed and long-acting in the body compared with shorter-chain forms. Our D3 + K2 uses MK-7 for exactly that reason.
D3 + K2 beyond bones
The pairing isn't only about bones. Vitamin D3 also contributes to the normal function of the immune system and normal muscle function — which is why it's the most useful single supplement for UK adults in winter (see our piece on vitamin D in a UK winter). So a D3 + K2 tablet does double duty: bone maintenance from both vitamins, plus D3's broader roles.
How to choose and take it
- Look for D3 (not D2) — the form the body makes from sunlight, and the one in our tablet.
- Look for K2 as MK-7 — the well-absorbed, long-acting form.
- Take with food containing some fat — both are fat-soluble vitamins, so a meal aids absorption.
- Note for blood-thinner users: vitamin K can interact with anticoagulants like warfarin — if you take one, check with your GP before starting K2.
The takeaway
For bone maintenance, D3 + K2 is the honest, claim-backed choice: two vitamins, both carrying authorised bone claims, working through complementary pathways, with K2 as the well-absorbed MK-7 form. Our Vitamin D3 + K2 is built exactly that way. For the full bones-and-joints picture, see our main guide.
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you are pregnant, breastfeeding, taking medication (especially anticoagulants) or managing a medical condition, speak to your GP or pharmacist before starting a new supplement. Signed, Dr. Miron, Founder of Pure Vitamins UK.
