Diet and nutritional supplements

What is it?

A good diet is essential for health, and many complementary and alternative therapists advise on diet. Dietary changes can help many people with arthritis, both inflammatory types and osteoarthritis.

As well as having a healthy, balanced diet, getting additional nutrients from food supplements may help if you have arthritis.

Are they safe?

For more information on the above and many more supplements and alternative medicines, see our authoritative report. This report has a detailed safety and effectiveness scoring system for each product.

Read more about complementary and alternative medicines for the treatment of rheumatoid arthritis, osteoarthritis and fibromyalgia.

Omega-3 fatty acids for inflammatory arthritis

Omega-3 polyunsaturated fatty acids EPA and DHA (found naturally in oily fish) can be helpful if you have inflammatory arthritis (including rheumatoid arthritis, reactive arthritis, psoriatic arthritis and ankylosing spondylitis, but not gout). Quite large amounts of omega-3 are needed for the best effects, so a concentrated fish oil supplement providing 3 g of EPA and DHA (i.e. total EPA + DHA) is available.

Fish oils act quite slowly, so you may want to try them for 3 months to see if you notice any benefit.

Some people find high doses of fish oils upset their stomach. If this is a problem you could try taking two or three smaller doses during the day. Or try eating oily fish instead – at least twice a week, but not more than four times a week. However, if you have gout, ily fish is generally best avoided.

If you’re vegetarian, or fish oil disagrees with you, you can get other types of omega-3 fatty acids from flaxseed oil, rapeseed oil and walnuts, but we don’t know whether they’re as beneficial as the EPA and DHA found in fish oil.

It's important not to confuse fish oil with fish liver oil. Lots of people take cod liver oil for osteoarthritis, but there’s no evidence to show that it makes a difference to the condition. Also, large doses of fish liver oil could potentially result in an overdose of vitamin A – this is particularly dangerous in women who are pregnant or might become pregnant because too much vitamin A could be harmful to an unborn baby. If you want to increase your intake of omega-3 fatty acids, we recommend taking pure fish oil rather than fish liver oil.

Vitamin E

There’s some evidence to suggest that vitamin E can play a role in the treatment of arthritis by preventing damage in the cells of your bones and joints. It may also have anti-inflammatory properties.

It’s important to include vitamin E in your diet, especially if you’re taking a lot of fish oil, but you should avoid doses of more than 400 mg a day of vitamin E. The following foods are rich in vitamin E:

  • plant oils (including soya, wheat and olive)
  • wheatgerm
  • sunflower seeds
  • nuts
  • avocado.


Mild selenium deficiency is quite common and it has been suggested that deficiency may result in your arthritis progressing more quickly, although there’s doubt about this. Selenium is usually derived from yeast for medicinal purposes. It’s available as part of most vitamin or mineral supplements or on its own in the form of capsules.

Vitamin D

Why do we need vitamin D?

We all need vitamin D to help maintain strong and healthy bones, and it also plays several other important roles to improve the body's health and wellbeing.

Vitamin D is important to process and regulate the amount of calcium and phosphate within your body. These nutrients help to develop the structure and strength of your bones.

A lack of vitamin D can lead to the development of a condition called osteoporosis, which causes the insides of bones to be weak, and therefore at risk of breaking.

Not having enough vitamin D can also lead to the development of osteomalacia, which causes the outer shell of bones to be soft; this condition can also be known as rickets.

Other than bone health, vitamin D helps your body to have healthy muscles. And it’s thought that vitamin D can boost your immune system (the body’s self-defence mechanism), as well as improve the health of your heart and lungs. Research has suggested that vitamin D has a role to play in reducing the risk of some forms of cancer.

The sunshine vitamin

Vitamin D is sometimes called the 'sunshine vitamin', because the best source of the vitamin is from sunlight. In fact sunlight on the skin allows the body to produce vitamin D itself.

From June to August in the UK, getting an average of 15 minutes a day of sunlight on bare skin (for example bare arms, legs and face) should be enough for most people to get their recommended daily amount of vitamin D.

However, in the UK we can't rely on sunshine alone to get all the vitamin D we need, certainly not all year round. And while there are foods containing vitamin D, it's difficult to meet the recommended daily amount simply from what you eat.

Making sure you get enough vitamin D

Because vitamin D is so important for bone health, Public Health England, a body which advises the government on health matters, says we should all take daily supplements, for at least part of the year.

In the autumn and winter months, everyone should consider taking a 10 microgram vitamin D supplement every day.

While most people will be able to get enough vitamin D from a combination of sunlight and a healthy diet through the spring and summer months, this is not the case for everyone.

The following groups of people are advised to take supplements all-year round

  • Those who don't go outside enough, for example people who are housebound or live in a care home
  • Anyone who wears clothes which cover the whole of the body and/or the face
  • Ethnic minority groups with dark skin, including people from African, Afro-Caribbean and South Asian backgrounds, because people with dark skin pigmentation are less able to absorb vitamin D through the skin.

Public Health England recommends that children aged one to four should have a daily 10 microgram vitamin D supplement, and that babies under one year should have a daily vitamin D supplement of between 8.5 and 10 micrograms.

Children who have more than 500 ml of infant formula a day do not need any additional vitamin D as formula has the vitamin contained in it.

Vitamin D in foods

Foods which naturally contain vitamin D, include eggs and oily fish, particularly herrings, salmon and mackerel. Some foods are fortified with vitamin D, such as margarine, various breakfast cereals and powdered milk.

Can I have too much vitamin D?

Taking more than 100 microgram of vitamin D as supplement a day can be harmful.

For most people, taking a 10 microgram vitamin D supplement every day will be enough.

Having too much vitamin D from a supplement over a long period of time, can lead to a build up of calcium in the body, a condition called hypercalcaemia. This can weaken bones and can be bad for the heart and kidneys.

If you have any concerns, you should consult a doctor.

It’s not possible to get too much vitamin D from sunlight, but you should avoid the risk of getting sunburnt by covering up if you are out in the sunshine for long periods. Sunburn can increase the likelihood of developing skin cancer later in life.

Glucosamine sulphate and chondroitin for osteoarthritis

Many people take glucosamine sulphate tablets with or without added chondroitin for osteoarthritis. Cartilage contains substances related to glucosamine and chondroitin, and taking supplements of these natural ingredients may nourish damaged cartilage. Research results are mixed but suggest that some people will benefit from this therapy.

Research suggests glucosamine sulphate is more likely to be helpful than glucosamine hydrochloride. If you're thinking of trying glucosamine we suggest taking 1500 mg per day of glucosamine sulphate. You may want to try glucosamine and chondroitin supplements for 3 months, and if your joint pain improves you can choose to continue with them.

If you’re allergic to shellfish, there are vegetarian or shellfish-free forms of glucosamine available.

Glucosamine can increase the level of sugar in the blood, so if you have diabetes it would be useful to discuss glucosamine with your doctor before you start to take it. You should also speak with your doctor if your blood sugars seem to be rising after starting glucosamine.

If you’re taking warfarin your blood-thinning control (international normalised ratio or INR) may be affected, so make sure you have your regular blood checks and discuss using glucosamine with your doctor.

Exclusion diets

Some people find that certain foods aggravate their arthritis and avoid these foods. The only way to be sure that you have a food intolerance is by dietary 'exclusion and challenge' where you leave out a certain food for several weeks. This is followed by a 'challenge', where you reintroduce the food to see if it causes a reaction. If your arthritis is related to a food allergy you'll notice a flare-up of your symptoms within a few days. It's important to cut out each food you're testing completely and re-introduce them one at a time.

It's better, if possible, to eat a balanced diet, rather than relying on nutritional supplements. For instance, for most people dairy products (milk, cheese, yogurt) are important sources of calcium, which is essential for strong bones. If you don't eat dairy products you will need to think about other sources of calcium.