Reviewed and updated: 5 November 2026
Best vitamin D3 and K2 supplements UK: buyer's guide 2026
The best vitamin D3 and K2 supplements in the UK use D3 (cholecalciferol) rather than D2, pair it with K2 as MK-7, print both amounts clearly in micrograms and IU, stay inside the UK upper limit for vitamin D, and say plainly where and how they are made. That is the short answer, and the rest of this guide is the detail behind it: why each of those choices matters, how to read the numbers on a label, what the UK guidance says about winter and year-round use, the one interaction you must know about before you buy, and a price-per-day sum you can repeat on any product. I have written it as a how-to-choose guide, so you can use it with any brand, including ours.
The pouch I turn over first, because the doses are on the back where I can compare them.
Quick answer (TL;DR)
- What to look for: D3 (not D2), K2 as MK-7, both amounts clearly labelled, and a clean formula from a GMP-certified facility.
- Who it is for: adults topping up vitamin D, especially over the darker UK months. Vitamin D contributes to normal immune function, normal muscle function and the maintenance of normal bones, and vitamin K contributes to normal blood clotting and the maintenance of normal bones.
- Dose in one line: UK advice is to consider 10 micrograms (400 IU) a day in autumn and winter, and the adult upper limit for vitamin D from all sources is 100 micrograms (4,000 IU) a day.
- Key caution: vitamin K can interact with warfarin and similar anticoagulants, so talk to your doctor or pharmacist before taking K2.
Our pick for this guide
Looking for D3 and MK-7 together with both doses on the label?
Our Vitamin D3 + K2 Tablets give you 4000 IU (100 micrograms) of D3 as cholecalciferol with 100 micrograms of K2 as MK-7 in one vegetarian tablet a day. A food supplement, not a replacement for medical advice.
From £14.99 · 30 tablets, 30 days
Shop Vitamin D3 + K2 →How this guide was researched
I wanted this to be something you can check, so here is how I built it. I read the NHS and Scientific Advisory Committee on Nutrition (SACN) guidance on vitamin D, looked up the human studies on D2 versus D3 and on MK-7 in PubMed and read the original papers rather than summaries, and compared what labels on UK shelves actually print. I do not rank other brands. Instead the guide gives you the criteria, and for the worked examples I use the values printed on our own pouch, so you can see every number. Where the research is mixed, I say so.
Why D3 rather than D2?
Vitamin D comes as D2 (ergocalciferol, from yeast and fungi) or D3 (cholecalciferol, the form your skin makes in sunlight and the one found in oily fish and eggs). Both appear in supplements, but D3 has the stronger case. According to PubMed, a 2012 systematic review and meta-analysis of randomised trials that compared the two directly concluded that D3 was more effective than D2 at raising blood 25-hydroxyvitamin D (the usual marker of vitamin D status), although the difference was clearest with large single doses and was not seen with daily dosing in that analysis (Tripkovic and colleagues, 2012, American Journal of Clinical Nutrition, DOI 10.3945/ajcn.111.031070, read it on PMC). So the honest summary is that D3 is the better-supported choice, and for a UK buyer with limited winter sun it is the form I would pick. More in vitamin D3 versus D2.
K2 as MK-7 versus MK-4, and typical amounts
Vitamin K2 is a family of menaquinones, and the two you will meet in supplements are MK-4 and MK-7. MK-7 is the long-chain form, usually made by fermentation, and it stays in the bloodstream much longer than the short-chain vitamin K1 or MK-4, which generally clear within hours. According to PubMed, a study in healthy volunteers comparing synthetic vitamin K1 with MK-7 found both were absorbed well, peaking around four hours after intake, but MK-7 had a very long half-life, giving much more stable blood levels and accumulating to roughly seven to eight times higher levels over prolonged intake (Schurgers and colleagues, 2007, Blood, DOI 10.1182/blood-2006-08-040709, read it on PubMed). That is the practical reason a once-a-day MK-7 tablet makes sense.
On amounts, MK-7 products on UK shelves commonly provide somewhere between 45 and 200 micrograms per serving. The UK nutrient reference value for vitamin K is 75 micrograms, and our tablet provides 100 micrograms of K2 as MK-7. The same paper carries a warning that matters for the safety section below: preparations supplying 50 micrograms a day or more of MK-7 may interfere with oral anticoagulant treatment.
IU, micrograms and the NRV: reading the numbers
Labels switch between units, which is where most confusion starts. For vitamin D, 1 microgram equals 40 IU. So the 10 micrograms in UK public-health advice is 400 IU, and the 4,000 IU on our pouch is 100 micrograms. The nutrient reference value for vitamin D is just 5 micrograms (200 IU), so a high-strength tablet will show a very large percentage of the NRV, which is normal and says nothing about whether it suits you. Look instead at the absolute amount per serving and compare it with the guidance. For vitamin K, amounts are always in micrograms, and K2 is often listed as MK-7 with the microgram figure beside it, sometimes with a separate vitamin K1 line, so check which form the number refers to.
What vitamin D3 and K2 are each recognised for
Both are vitamins with recognised roles at meaningful amounts. Vitamin D contributes to the normal function of the immune system, to normal muscle function, to the maintenance of normal bones and teeth, to the normal absorption and utilisation of calcium and phosphorus and to normal blood calcium levels. Vitamin K contributes to normal blood clotting and to the maintenance of normal bones. People pair them because vitamin D contributes to normal calcium absorption while vitamin K contributes to the maintenance of normal bones, so each covers a different part of the same bone story. I go deeper in vitamin D3 and K2 for bone health.
Winter only or all year: what UK guidance says
NHS advice is that everyone should consider taking 10 micrograms (400 IU) of vitamin D a day during autumn and winter, because from roughly October to March the sun in the UK is not strong enough for the skin to make it. Some groups are advised to take it all year, including people who spend little time outdoors, who cover most of their skin outside, or who have darker skin, which makes less vitamin D from the same sunlight. SACN, which advises the UK government, set that 10 microgram reference intake for the population, and for most people that amount is enough. Higher-strength products exist for people who want a larger top-up, and that is a decision best made knowing your own situation, ideally with a GP or pharmacist, rather than assuming bigger is better.
How much to take, and the safe upper limit
The UK safe upper limit for vitamin D for adults is 100 micrograms (4,000 IU) a day from all sources combined, meaning supplements and fortified foods together. Our tablet sits right at that figure, which is exactly why I tell people not to stack it on top of another vitamin D product, a multivitamin with a large vitamin D dose, or cod liver oil without adding up the totals. Taking much more than the limit for long periods can raise blood calcium to unhealthy levels. If you want a lower daily strength, whether 1000 IU of vitamin D3 a day is a good dose compares it with the UK baseline. And because the right amount depends on your starting point, a blood test through your GP is the only way to know your status.
Tablet, capsule, liquid or spray
Format changes convenience more than quality, but each has a quirk worth knowing.
- Tablets: compact, stable and usually inexpensive, with no oil carrier. Because vitamin D is fat-soluble, you take them with a meal that contains some fat. Ours is a small vegetarian tablet.
- Softgel capsules: the vitamin is dissolved in oil, which some people find easier to absorb without a meal, but most softgels use gelatin and are not suitable for vegetarians or vegans.
- Liquid drops: flexible dosing and easy for people who dislike swallowing tablets, though accurate dosing depends on counting drops and many use an oil carrier.
- Oral sprays: convenient, but check the dose per spray and how many sprays make a serving, since the amount per spray is often small.
Vegan and lichen-sourced D3
Most D3 comes from lanolin, the grease in sheep's wool, so it is animal-derived. A smaller number of products use D3 from lichen, which is plant-based and suitable for vegans. Ours uses lichen-sourced D3, and MK-7 is made by fermentation, so the formula suits a vegan diet. If this matters to you, check the label for the source of the D3 and not only for the word vegetarian.
Reading the label: fillers, excipients and testing
Beyond the two headline doses, a good label tells you a few more things. Check the serving size, because a figure per two tablets is not the same as per tablet. Check what else is in the tablet: many use a little cellulose, a bulking agent or a flow agent, which are widely used and fine for most people, but a short ingredient list is easier to judge. Look for a clear statement about how the product is made and checked. Ours is formulated in the UK and tested for purity and heavy metals at our GMP-certified facility. And be wary of any label that promises results rather than describing what is in the tablet.
Exactly what I was looking for
“I knew which ingredients I wanted and liked having them together in one simple product.”
What to take it with: food, fat, calcium and magnesium
Both vitamins are fat-soluble, so take your tablet with a meal that contains some fat, such as eggs, yoghurt, nuts or oily fish, and not on an empty stomach. Timing through the day is a matter of habit, and I set out the practical options in what time of day is best to take vitamin D3 and K2. If you also take magnesium, which works alongside vitamin D in the body, the best time to take vitamin D3 and magnesium glycinate and what kind of magnesium to take with vitamin D3 and K2 cover how to fit them together. If you take a calcium supplement as well, remember that vitamin D contributes to normal calcium absorption, so check your total calcium intake with a pharmacist rather than adding it blindly.
Price per day: a worked example
The fair way to compare is cost per day and cost per unit of vitamin D, not pack price. Divide the price by the number of servings, then divide that by the amount per serving. Here is the sum with our own pouch at today's price: £14.99 for 30 tablets is 30 servings, so about 50p a day. With 4,000 IU in each tablet, that is roughly 12p for every 1,000 IU of vitamin D3, with 100 micrograms of MK-7 included.
Run the same sum on any product you are considering. A cheap D3-only pack may look better value until you add the cost of a separate K2 product. A 1,000 IU combination may cost less per pack but give you a quarter of the D3, so the cost per 1,000 IU can end up higher. And a liquid with a small dose per drop can look cheap until you count the drops in a serving.
Who should speak to a GP or pharmacist first
Vitamin D3 and K2 suit most healthy adults, but a few groups should get advice before starting:
- Warfarin and similar anticoagulants: vitamin K plays a role in normal blood clotting, so it can interact with vitamin K antagonist medicines. Do not start a K2 supplement without speaking to your doctor or anticoagulant clinic first, and tell them if you stop.
- High blood calcium, kidney problems or sarcoidosis: high-strength vitamin D can raise blood calcium, so get advice first.
- Pregnancy and breastfeeding: speak to your GP or pharmacist about the right vitamin D amount.
- Other regular medicines: some can affect how the body handles vitamin D or calcium, so check with your pharmacist.
- Children and under-18s: this product is for adults only, and children's amounts are different.
Food sources and signs you may be low
Vitamin D is found in oily fish such as salmon, mackerel and sardines, egg yolks, red meat and fortified foods, but diet alone rarely covers UK winter needs, which is why supplementation is commonly advised. Vitamin K1 comes from leafy greens such as spinach and kale, and K2 from fermented foods like natto and some cheeses. Low vitamin D is loosely associated with tiredness and aches, but these have many causes, so symptoms alone cannot tell you your status. The NHS page on vitamin D explains who is most at risk and when to speak to a GP (NHS: vitamin D).
Storage and shelf life
Keep the pouch sealed in a cool, dry place away from direct sunlight, with the seal closed after each use and out of reach of children. Check the best-before date on the pack. Vitamin D tablets are fairly stable, but heat and damp shorten the life of any supplement, so a kitchen shelf above the kettle is not ideal.
The buyer's checklist
- D3 (cholecalciferol), not D2, with the source stated if you want plant-based.
- K2 as MK-7, with the microgram amount printed.
- Both doses on the label in IU and micrograms, per serving, with the serving size clear.
- Total vitamin D from all your supplements at or under 100 micrograms (4,000 IU) a day.
- A short ingredient list, and suitable for your diet.
- Cost worked out per day and per 1,000 IU.
- A plain statement about where and how it is made and checked.
- An honest label, with no promises of results.
Where Pure Vitamins fits
I built our Vitamin D3 + K2 tablets around exactly this checklist: 4,000 IU of D3 and 100 micrograms of K2 as MK-7 in one vegetarian tablet, lichen-sourced D3, formulated in the UK and made in a GMP-certified facility. You can browse every guide on the supplement guides hub and the full range on the Pure Vitamins UK home page. If you want more on the immune side of the picture, I have a guide to the best vitamins for immunity in the UK.
Frequently asked questions
What is the best vitamin D3 and K2 supplement in the UK?
The best one is the product that uses D3 and MK-7, prints both amounts per serving, keeps total vitamin D within the UK upper limit of 100 micrograms (4,000 IU) a day, and is made in a GMP-certified facility. Compare cost per day and per 1,000 IU, not just the pack price.
Is D3 better than D2?
For raising blood vitamin D levels the evidence favours D3, which is why most good supplements use it, although the difference is clearest with large single doses.
Why combine D3 with K2?
Vitamin D contributes to normal calcium absorption and the maintenance of normal bones, while vitamin K contributes to the maintenance of normal bones and normal blood clotting, so many people prefer to take them together.
How much vitamin D should I take per day?
UK advice is to consider 10 micrograms (400 IU) a day in autumn and winter, and all year for some groups. Higher-strength products exist, but 100 micrograms (4,000 IU) a day from all sources is the adult upper limit and should not be exceeded.
Can I take K2 with warfarin?
Not without medical advice. Vitamin K can interact with warfarin and similar anticoagulants, so speak to your doctor or pharmacist first.
Should I take D3 and K2 with food?
Yes. Both are fat-soluble, so take your tablet with a meal that contains some fat.
Is vitamin D3 vegan?
Most D3 comes from lanolin, which is animal-derived, but D3 from lichen is plant-based. Our tablet uses lichen-sourced D3, with MK-7 made by fermentation.
Do I need vitamin D in summer?
Many people make enough from sunlight between roughly April and September, but some groups are advised to take it all year, including people who are rarely outdoors or who cover most of their skin.
How much does D3 and K2 cost per day?
Divide the pack price by the number of servings. Our pouch is £14.99 for 30 tablets, about 50p a day at today's price.
This article is for general information and is not medical advice. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you take anticoagulants, are pregnant or breastfeeding, have kidney problems or high blood calcium, or manage a medical condition, speak to your GP or pharmacist before starting a new supplement.
Signed, Dr. Miron, Founder of Pure Vitamins UK.
Related articles
- Vitamin D3 vs D2: which form to choose
- Vitamin D3 and K2 for bone health
- Vitamin D in winter in the UK
- What time of day is best to take vitamin D3 and K2?
- Is it good to take 1000 IU of vitamin D3 daily?
- Best time to take vitamin D3 and magnesium glycinate
- Best vitamins for immunity UK
- Vitamin D3 + K2 tablets (4,000 IU D3 + MK-7)
Our pick for this guide
Ready to check a D3 and K2 label against your list?
Our Vitamin D3 + K2 Tablets pair lichen-sourced D3 with K2 as MK-7 in one daily vegetarian tablet, with both doses printed on the pouch. A food supplement, not a replacement for medical advice.
From £14.99 · 30 tablets, 30 days
Shop Vitamin D3 + K2 →Sources
- Tripkovic L and colleagues (2012). Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. American Journal of Clinical Nutrition. DOI 10.3945/ajcn.111.031070. PMC3349454
- Schurgers LJ and colleagues (2007). Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. DOI 10.1182/blood-2006-08-040709. PubMed 17158229
- NHS. Vitamin D
