Quick answer: The NHS advises everyone in the UK to consider a daily 10 microgram (400 IU) vitamin D supplement in autumn and winter, and all year round if you are rarely outdoors, live in a care home, cover most of your skin or have dark skin. Vitamin D is important for bones and muscles, but trials have not shown that it treats osteoarthritis pain. Do not take more than 100 micrograms a day unless a doctor advises it.
Evidence checked on 10 October 2026 against NHS: Vitamin D, the BDA vitamin D food fact sheet and published trials listed below.
Vitamin D is one of the few supplements that UK health advice actually recommends for most people, at least for part of the year. It is also surrounded by bold claims online, from "cures joint pain" to "everyone needs a high dose". This guide sets out what the NHS advises, what the research shows for arthritis specifically, and how to take vitamin D safely alongside your other treatment.
Why vitamin D matters
The NHS explains that vitamin D helps regulate the amount of calcium and phosphate in the body, which are needed to keep bones, teeth and muscles healthy. A lack of vitamin D can cause bone pain from a condition called osteomalacia in adults. The British Dietetic Association (BDA) adds that vitamin D helps maintain muscle strength, which helps prevent falls, and supports the immune system.
For people with arthritis, this matters in a few specific ways:
- Bone health. Some types of arthritis, and some treatments such as long-term steroid tablets, increase the risk of osteoporosis.
- Muscle strength and falls. Strong muscles protect painful joints and help you stay steady. See our guide to vitamin D and falls.
- Less time outdoors. Pain, stiffness and fatigue can mean spending more time indoors, which reduces the vitamin D your skin makes.
- Aches that overlap. Osteomalacia can cause bone pain and muscle weakness that can be mistaken for, or add to, arthritis symptoms.
How much do you need?
The NHS says children from the age of 1 and adults need 10 micrograms (mcg) of vitamin D a day. This is the same as 400 international units (IU), because 1 microgram equals 40 IU.
| Who | NHS advice |
|---|---|
| Adults and children over 4 | Consider a daily 10 microgram supplement during autumn and winter (roughly October to early March) |
| Adults who are not often outdoors, for example frail or housebound | Take 10 micrograms daily all year round |
| People living in a care home or other institution | Take 10 micrograms daily all year round |
| People who usually cover most of their skin outdoors | Take 10 micrograms daily all year round |
| People with dark skin, for example of African, African-Caribbean or south Asian background | Consider 10 micrograms daily all year round |
From about late March or early April to the end of September, the NHS says most people can make all the vitamin D they need from sunlight on their skin. Between October and early March, the sun is not strong enough in the UK.
Food and sunlight
Vitamin D is found in a small number of foods. The NHS lists:
- oily fish, such as salmon, sardines, trout, herring and mackerel
- red meat
- egg yolks
- fortified foods, such as some fat spreads and breakfast cereals
- liver (avoid if you are pregnant)
The BDA adds some mushrooms and fortified unsweetened soya drinks. But both the NHS and BDA say it is difficult to get enough vitamin D from food alone. In the UK, cows' milk is generally not fortified, so it is not a good source.
Eating oily fish twice a week helps, and also gives you omega-3 fats, which are part of an anti-inflammatory style of eating. The NHS advises at least 2 portions of fish a week, 1 of which should be oily.
In summer, short periods of sun on bare skin help your body make vitamin D. You cannot overdose on vitamin D from sunlight, but the NHS reminds you to cover up or protect your skin to reduce the risk of sunburn and skin cancer. Some medicines can make your skin more sensitive to the sun, so check your medicine leaflets and ask your pharmacist if you are unsure.
What the research shows for arthritis
This is where claims online often go further than the evidence.
Osteoarthritis
A two-year randomised trial published in JAMA in 2016 (Jin and colleagues) gave vitamin D or a placebo to people with symptomatic knee osteoarthritis who had low vitamin D levels. Vitamin D did not make a significant difference to knee cartilage volume measured on MRI or to knee pain scores. The authors concluded that the results do not support vitamin D supplements to prevent cartilage loss or improve knee pain in osteoarthritis.
So vitamin D is important for your bones and muscles in general, but it should not be expected to ease osteoarthritis pain.
Rheumatoid arthritis and autoimmune conditions
Low vitamin D levels are often reported in people with inflammatory arthritis, but that does not prove that low vitamin D causes it, or that supplements treat it. The large VITAL trial in the United States (Hahn and colleagues, BMJ 2022) found that five years of vitamin D supplements, with or without omega-3, reduced the number of new autoimmune disease diagnoses in older adults compared with placebo. This was a prevention study in people without autoimmune disease, so it does not show that vitamin D treats rheumatoid arthritis once you have it.
NICE does not recommend vitamin D as a treatment for rheumatoid arthritis or osteoarthritis. Your rheumatology team may still check or recommend it to protect your bones.
Summary
| Question | What the evidence says |
|---|---|
| Do I need vitamin D for healthy bones and muscles? | Yes. NHS advice applies to people with arthritis too |
| Will vitamin D ease osteoarthritis pain? | A good-quality trial found no benefit for knee pain |
| Will vitamin D treat rheumatoid arthritis? | Not shown. One large trial suggests it may help prevent autoimmune disease, but that is different from treatment |
| Is a higher dose better? | No. 10 micrograms a day is enough for most people unless a doctor advises otherwise |
Taking too much
The NHS warns that taking too much vitamin D over a long period can cause too much calcium to build up in the body (hypercalcaemia), which can weaken bones and damage the kidneys and heart.
- Adults, including older people and those who are pregnant or breastfeeding, should not take more than 100 micrograms (4,000 IU) a day unless a doctor advises it.
- Some people have medical conditions that mean they cannot safely take as much. If in doubt, ask your doctor.
- If your doctor has prescribed a different dose, for example a short high-dose course for deficiency, follow their advice.
Check the labels of everything you take. Vitamin D can be in multivitamins, calcium tablets, fish liver oils and "joint" supplements, and amounts can add up. Fish liver oil (such as cod liver oil) also contains vitamin A, which can be harmful in large amounts and should be avoided in pregnancy.
Vitamin D and arthritis medicines
- Steroid tablets such as prednisolone, taken for a long time, can weaken bones. Your doctor may prescribe calcium and vitamin D, sometimes with a bone-protecting medicine. Take what is prescribed rather than adding your own supplement on top, unless your doctor agrees.
- Prescribed calcium and vitamin D tablets already contain vitamin D. You usually do not need an extra over-the-counter vitamin D supplement as well. Ask your pharmacist.
- Kidney disease, sarcoidosis or high calcium levels can change how much vitamin D is safe. Check with your doctor before taking a supplement.
- Methotrexate: the NHS advises not taking supplements that contain folic acid if you are already taking prescribed folic acid. Some multivitamins with vitamin D also contain folic acid, so check the label.
Tell your doctor or pharmacist about every vitamin and supplement you take, as the NHS advises for many arthritis medicines.
Do I need a blood test?
You do not need a blood test to follow NHS advice on a daily 10 microgram supplement. Your GP may arrange a vitamin D test if you have symptoms that could be due to deficiency, such as bone pain or muscle weakness, if you have osteoporosis or a condition that affects how you absorb nutrients, or before some treatments. If a test shows a deficiency, your doctor will advise on a treatment dose and how long to take it for.
Private home test kits are widely sold. If you use one, discuss the result with your GP or pharmacist rather than starting a high-dose supplement on your own.
Choosing a supplement
- Dose: look for 10 micrograms (400 IU). Many products contain much more; that is not necessary for most people.
- Form: most supplements contain vitamin D3. Vitamin D2 and some D3 products are suitable for vegans; check the label.
- Cost: basic vitamin D supplements from pharmacies and supermarkets are usually inexpensive. You do not need a "joint health" product to get vitamin D.
- Healthy Start: women and children who qualify for the Healthy Start scheme can get free vitamin supplements containing vitamin D.
A simple plan
- From October to March, take 10 micrograms of vitamin D a day.
- If you rarely go outside, live in a care home, cover most of your skin, or have dark skin, take it all year round.
- Eat oily fish and eggs regularly, and choose fortified foods if you like them.
- In summer, spend short periods outside when you can, without burning. Even sitting in a garden or by an open window helps more than staying indoors all day.
- Do not take more than 100 micrograms a day unless your doctor advises it.
- Tell your GP, pharmacist or rheumatology team what you take.
Pair vitamin D with calcium-rich foods such as milk, yoghurt, cheese, fortified plant drinks, tinned fish with soft bones and green leafy vegetables. Our calcium foods guide has easy ideas. For older adults and people who struggle to get outdoors, see our guide to vitamin D in winter.
When a dietitian can help
If you eat a restricted diet (for example vegan, dairy-free or very low in fish), have a condition that affects absorption such as coeliac disease or inflammatory bowel disease, or have had weight-loss surgery, ask your GP about a referral to a registered dietitian. They can check whether you are getting enough vitamin D, calcium and other nutrients.
When to get medical help
See your GP if you have bone pain, muscle weakness or aches that are not explained by your arthritis, if you have broken a bone after a minor fall, or if you take long-term steroids and have not had your bone health discussed. Seek medical advice if you take vitamin D supplements and develop symptoms that could suggest high calcium, such as feeling very thirsty, passing a lot of urine, feeling sick, constipation or confusion. Get same-day advice from your GP or NHS 111 if a joint suddenly becomes hot, swollen and very painful, especially with a fever.
Frequently asked questions
How much vitamin D should I take with arthritis?
The same as the general NHS advice: 10 micrograms (400 IU) a day in autumn and winter, or all year if you are in an at-risk group. Your doctor may advise a different dose if you have a deficiency or osteoporosis.
Can vitamin D help joint pain?
A good-quality trial in knee osteoarthritis found that vitamin D did not improve knee pain. Correcting a genuine deficiency can ease bone pain and muscle weakness caused by osteomalacia, which is different from arthritis pain.
Is 1,000 IU or more a day better?
Not for most people. 10 micrograms (400 IU) is enough for most adults. Do not take more than 100 micrograms (4,000 IU) a day unless a doctor advises it.
Can I take vitamin D with methotrexate?
Vitamin D on its own is not known to be a problem, but some multivitamins contain folic acid. The NHS advises not taking extra folic acid if you are already prescribed it. Check with your pharmacist.
Do I need vitamin D in summer?
Most people can make enough from sunlight between late March or early April and September. If you rarely go outside or cover your skin, the NHS advises taking it all year.
Should I get my vitamin D level tested?
Not routinely. You can follow NHS supplement advice without a test. Your GP may test if you have symptoms of deficiency or certain conditions.
Sources and further reading
- NHS: Vitamin D
- BDA: Vitamin D food fact sheet
- Arthritis UK: Diet and nutritional supplements (vitamin D)
- Jin X et al. Effect of vitamin D supplementation on tibial cartilage volume and knee pain in knee osteoarthritis. JAMA 2016 (PMID 26954409)
- Hahn J et al. Vitamin D and marine omega-3 supplementation and incident autoimmune disease: VITAL randomised controlled trial. BMJ 2022 (PMID 35082139)
- NHS: Fish and shellfish
Educational information for people in the United Kingdom — not personal medical or dietary advice. Food and supplements can interact with medicines, so check with your GP, pharmacist or rheumatology team before changing your diet significantly or starting a supplement, and ask for a referral to a registered dietitian for individual advice. Charity no. 1218461. Pending clinical and editorial review. If you feel very unwell, call 999 or go to A&E. For urgent advice, contact NHS 111.
Continue with related help
- Vitamin D and falls — bones, muscles and balance
- Vitamin D in winter — for older and frailer adults
- Calcium foods — easy ways to protect bones
- Anti-inflammatory diet — the evidence-based approach
- Omega-3 evidence review — fish oil and arthritis