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The bottom line for nutrition geeks
If you’re taking higher-strength vitamin D, pairing it with K2 (MK-7) is the smart move: D3 raises calcium, K2 helps route it to bone rather than soft tissue. One capsule, both halves of the system.
Vitamin D3 gets all the attention — but on its own it only does half the job. The partner that decides where the calcium it unlocks actually ends up is vitamin K2. Here’s why we never sell one without the other.
Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight, and it’s the one your body raises most effectively in the blood. Its headline job is to increase how much calcium you absorb from food in the gut. That’s essential for immunity, bones and muscle function — and exactly why so many people in the UK supplement it through the darker months.
But there’s a catch. D3 boosts the supply of calcium. It doesn’t decide where that calcium goes once it’s in your bloodstream. Take meaningful doses of D3 with nothing to direct the traffic, and you’re only managing one half of the system.
Vitamin K2 activates two key proteins: osteocalcin, which binds calcium into your bones, and matrix Gla protein (MGP), which helps keep calcium out of soft tissue like artery walls. In other words, K2 helps put the calcium D3 unlocked where you want it — in the skeleton — and away from where you don’t.
This is why the two are so often described as synergistic: D3 raises calcium availability; K2 helps direct its deposition. Pairing them is the logical way to take advantage of higher-strength D3.
K2 comes in different forms. We use MK-7, the long-chain menaquinone with a notably longer half-life in the body than the shorter MK-4 — meaning steadier levels from a single daily dose. Both D3 and K2 are fat-soluble, so the best time to take them is with a meal that contains some fat.
Our formula pairs 4000 IU of D3 with K2 as MK-7 in one capsule, so the partnership is built in — no second bottle, no guesswork.
If you’re taking higher-strength vitamin D, pairing it with K2 (MK-7) is the smart move: D3 raises calcium, K2 helps route it to bone rather than soft tissue. One capsule, both halves of the system.
Yes — this is the single most important rule. Both are fat-soluble vitamins, so they’re absorbed far better alongside a meal that contains some fat: eggs, avocado, olive oil, nuts or oily fish. Taking them on an empty stomach leaves absorption to chance.
With a fat-containing meal, whenever that is for you. The research is consistent that the hour on the clock doesn’t meaningfully change your vitamin D status — what matters is taking it with food and taking it consistently. Many people simply pair it with breakfast so they don’t forget.
D3 increases how much calcium you absorb; K2 (as MK-7) then activates the proteins — osteocalcin and matrix-Gla protein — that direct that calcium into your bones and away from soft tissue like arteries. Vitamin D contributes to the maintenance of normal bones and normal immune function, and vitamin K contributes to the maintenance of normal bones. Taking D3 without K2 does only half the job, which is why our Vitamin D3 + K2 pairs them in one capsule.
A widely used practical guide is roughly 100 mcg of K2 per 1,000 IU of D3. We use the MK-7 form of K2 rather than MK-4 because MK-7 has a much longer half-life, so a single daily capsule keeps levels topped up around the clock.
For much of the year, yes. Between about October and March, UK sunlight is too weak for your skin to make meaningful vitamin D, and many people run low year-round. That’s why a daily supplement through the darker months is so commonly recommended here.
D3 increases how much calcium you absorb, but it does not control where that calcium goes. K2 activates proteins that help bind calcium into bone and keep it out of soft tissue, so the two work as a system.
Both are forms of vitamin K2, but MK-7 has a longer half-life in the body, giving steadier levels from a single daily dose. We use MK-7.
Both are fat-soluble, so they are best taken with a meal that contains some fat for optimal absorption.
The baseline UK reference is 10 mcg (400 IU) a day. Our max-strength formula provides more for adults who want a higher intake through the winter or after testing low. If you’re unsure of your level, a simple 25(OH)D blood test can guide you.
Yes — because it’s fat-soluble it can build up, so it’s sensible not to exceed upper-intake guidance long term without testing or professional advice. Take the serving as directed.
For a once-a-day supplement, yes — MK-7 stays active in the body much longer than MK-4, so a single daily dose sustains levels rather than peaking and dropping quickly.
Yes — magnesium supports how your body metabolises vitamin D, so the two work well together. See our magnesium guide.