How much vitamin D3 and K2 should you take daily?
For most UK adults, how much vitamin D3 and K2 to take daily comes down to roughly 1,000 to 4,000 IU (25 to 100 micrograms) of vitamin D3, paired with about 75 to 200 micrograms of vitamin K2 as MK-7. The NHS minimum of 400 IU (10 micrograms) is set to prevent severe deficiency rather than to optimise levels, and 4,000 IU (100 micrograms) is the recognised safe upper limit for unsupervised daily intake. The rest of this guide helps you land on the right number for you, and shows how the two vitamins fit together. For a buyer's guide, see how to choose a vitamin D3 and K2 supplement.
Reviewed and updated: 23 July 2026
TL;DR
- Typical daily range: 1,000 to 4,000 IU D3 with 75 to 200 micrograms K2 (MK-7) for most adults.
- Who needs more: people with darker skin, over-65s, those who cover up or stay indoors, and anyone through a UK winter often sit at the higher end.
- The one thing to know: 4,000 IU is the safe ceiling without medical supervision, and if you take warfarin, check with your GP before adding K2.
NHS guidance versus research dosing: why the confusion
UK shelves carry vitamin D3 from 400 IU all the way to 4,000 IU per dose, the same vitamin at a tenfold difference in strength, which is understandably confusing. The reason is that two different goals are in play. The NHS recommends 10 micrograms (400 IU) a day for adults during autumn and winter, and year-round for higher-risk groups, a level set to prevent severe clinical deficiency. Much of the modern research on vitamin D and bone, muscle and immune outcomes has used daily doses between 1,000 and 4,000 IU, and both the European Food Safety Authority and the NHS recognise 4,000 IU (100 micrograms) as the safe upper limit for healthy adults supplementing without medical supervision. Both figures are right; they simply answer different questions. There is more in vitamin D and normal bones.
How much vitamin D3 per day?
The right dose depends on who you are and where you live. For general healthy adults, 1,000 to 2,000 IU (25 to 50 micrograms) daily through autumn and winter is a sensible starting point, and many UK adults continue year-round, particularly in Scotland and the north of England where summer UVB is limited. Higher-risk groups are advised by the NHS to supplement year-round, and for them 2,000 to 4,000 IU per day is often appropriate. Those groups include adults with darker skin, anyone who covers up outdoors, people over 65 (especially if housebound), pregnant and breastfeeding women, and people with conditions affecting fat absorption. The maximum without medical supervision is 4,000 IU (100 micrograms) per day. Higher doses are sometimes appropriate to correct a confirmed shortfall under GP guidance, which should involve a blood test (25-hydroxyvitamin D) and clinical input.
How much vitamin K2 (MK-7) per day?
Vitamin K2 appears in supplements as either MK-4 or MK-7. MK-7 is the form usually chosen for daily use because it stays active in the body considerably longer, so a single daily dose keeps levels steadier. Based on a comparison retrieved from PubMed, a nutritional dose of MK-7 was well absorbed and detectable for up to 48 hours, whereas the same dose of MK-4 did not raise blood levels (Sato et al., 2012, DOI). For most adults, 75 to 200 micrograms of MK-7 per day is the range used in current research alongside vitamin D3. One important interaction: if you take warfarin or another vitamin K-sensitive blood thinner, vitamin K2 can affect how it works, so speak to your GP or pharmacist before adding a K2 supplement. Newer anticoagulants (DOACs) are generally not affected, but always confirm. There is more in how to compare multivitamin formulas.
What is the right ratio of D3 to K2?
There is no single official ratio, and the body does not need a precise milligram-by-milligram match for the two to work alongside each other. A practical rule used across most reputable UK and European supplements is roughly 1 microgram of K2 (MK-7) for every 25 to 40 IU of D3. In practice that gives combinations such as 1,000 IU D3 with 25 to 50 micrograms MK-7 at the entry level, 2,000 IU D3 with 75 to 100 micrograms MK-7 for most adults, and 4,000 IU D3 with 100 to 200 micrograms MK-7 at the high-strength end for a UK winter or higher-risk groups.
Why dose matters more if you live in the UK
The UK sits between roughly 50 and 60 degrees north. From October to March the sun's angle is too low for skin to make meaningful vitamin D, however long you spend outdoors, which is sometimes called the vitamin D winter. UK government data from the National Diet and Nutrition Survey has reported that around one in six adults has a vitamin D blood level below the clinical deficiency threshold, rising in winter and higher in adults of South Asian, African and African-Caribbean heritage. This is why UK-specific dosing tends to run higher than advice from sunnier countries. We cover the seasonal picture in vitamin D in winter.
Can you take too much D3 or K2?
Yes, but it is harder than people often think. Vitamin D toxicity is rare and typically requires sustained intakes well above 10,000 IU per day over months; the concern is hypercalcaemia, too much calcium in the blood. Staying at or below 4,000 IU per day without medical supervision keeps you well within established safety limits. Vitamin K2 toxicity is essentially unheard of at supplemental doses, with the warfarin interaction noted above being the main consideration. Children's dosing is age-specific and should follow NHS Healthy Start guidance; adult-strength D3 is not suitable for babies or young children.
Timing and how to take it
Take D3 and K2 with your largest meal of the day, ideally one containing some fat, because both are fat-soluble and absorb better with food. Morning or evening both work, and consistency matters more than timing. They pair well with magnesium, omega-3 and most multivitamins; the exception is warfarin and similar anticoagulants, where you should speak to your GP or pharmacist first.
What D3 and K2 do for you
Vitamin D contributes to the maintenance of normal bones and teeth, to normal muscle function, to the normal function of the immune system, and to normal blood calcium levels, and it contributes to the normal absorption and utilisation of calcium. Vitamin K contributes to the maintenance of normal bones and to normal blood clotting. That is a genuinely complementary pairing, which is why so many people take them together, and we explain it in vitamin D3 and K2 for bone health. On the form question, a randomised trial retrieved from PubMed found vitamin D3 raised blood 25-hydroxyvitamin D more than vitamin D2 (Shieh et al., 2016, DOI), a finding echoed in a later trial where daily cholecalciferol outperformed weekly ergocalciferol (Amphansap et al., 2022, DOI), which is why D3 is the form to look for. See also what vitamin K2 MK-7 is.
Where Pure Vitamins fits
Our Vitamin D3 + K2 delivers 4,000 IU (100 micrograms) of D3 alongside 100 micrograms of vitamin K2 as MK-7 per tablet, the high-strength end of the everyday research-supported range, in vegetarian tablets. It is formulated in the UK and manufactured in a GMP-certified facility. If you prefer a lower, single-nutrient option, our Vitamin D3 1000 IU is the simpler choice. Browse the wider range on our Pure Vitamins UK home page.
Frequently asked questions
Can I take vitamin D3 every day? Yes. For most UK adults, daily supplementation through autumn and winter, and often year-round, is standard. Stay within 4,000 IU (100 micrograms) per day unless your GP advises otherwise.
When is the best time to take D3 and K2? With your largest meal, ideally one containing some fat, since both are fat-soluble. Consistency matters more than morning versus evening.
Do I need K2 if I already take D3? Pairing them is widely chosen for daily use, because vitamin D contributes to normal calcium absorption and vitamin K contributes to the maintenance of normal bones. For the other side of that question, see whether taking vitamin D3 without K2 is a concern.
How long does vitamin D take to work? Blood levels typically begin to rise within 2 to 4 weeks and stabilise after roughly 2 to 3 months. A blood test before and after gives the clearest picture.
Should I get my vitamin D level tested? It can be useful, especially in a higher-risk group or to fine-tune your dose. Your GP can arrange a blood test.
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. Do not exceed 4,000 IU (100 micrograms) of vitamin D daily without medical advice. If you take blood-thinning medication, speak to your GP before taking vitamin K2. If you are pregnant, breastfeeding, taking medication or managing a medical condition, speak to your GP or pharmacist before starting a new supplement.
Dr. Miron, Founder of Pure Vitamins UK.
