Nine out of ten British adults are low in vitamin D for at least part of the year. It's the supplement the NHS officially recommends during winter months, and the one most people buy first when they decide to start "taking something." But there's a quieter conversation happening among nutritionists about the supplement we should be pairing it with: vitamin K2.
What D3 actually does
Vitamin D3 contributes to:
- normal absorption and utilisation of calcium*
- maintenance of normal bones and teeth*
- normal muscle function*
- normal function of the immune system*
It does this in part by telling your gut to absorb more calcium from food. That calcium then enters the bloodstream and (ideally) gets directed to bones and teeth where you actually want it.
The piece D3 alone doesn't handle
D3 increases calcium absorption, but it doesn't tell that calcium where to go. That's K2's job. Vitamin K2 (specifically the MK-7 form) activates two proteins — osteocalcin and matrix Gla protein — that direct calcium toward bone tissue and away from soft tissue and arteries.
This is why you'll often see them sold together: D3 brings calcium in, K2 routes it correctly.
Why the MK-7 form specifically
There are two relevant forms of K2: MK-4 (short half-life, needs multiple daily doses) and MK-7 (24+ hour half-life, once-daily is fine). MK-7 is what we use in Nuvra D3+K2 for that reason — daily use without having to think about it.
Doses we use
- D3: 4000 IU per serving (100 µg). The upper safe limit in the UK is 4000 IU per day, so this fills the full daily ceiling.
- K2 (as MK-7): 100 µg per serving. The dose used in most published studies.
- Form: small vegetarian tablet, easy to swallow, 6-month supply per bottle.
Who should consider it
If you live in the UK, work indoors, or wear sunscreen daily (and you should), your D3 production is meaningfully reduced. Add 35+ years of age, darker skin tones, or a mostly indoor winter — and supplementation is the simplest fix. Adding K2 turns the supplement into a more complete package.
See Nuvra D3+K2 (6-month supply) →
*Authorised EFSA health claims for vitamin D. Food supplements are not a substitute for a varied, balanced diet. Not intended to diagnose, treat or prevent any condition. If pregnant, breastfeeding or on medication (including blood thinners), consult your GP before taking K2.