You get most of your vitamins and minerals from the food you eat rather than from supplements. Not having enough (a deficiency) of some vitamins and minerals seems to be linked with arthritis progressing more quickly. The most important vitamins and minerals to think about if you have arthritis are calcium, vitamin D and iron.
Calcium is important for keeping your bones healthy. Calcium deficiency increases your risk of osteoporosis, which causes the insides of bones to be weak, and therefore at risk of breaking. This condition is particularly common in women after the menopause. You may also be at risk of developing osteoporosis if you're taking steroids on a long-term basis.
A lack of calcium in your diet can also increase your risk of developing a condition called osteomalacia, which causes the outer shell of bones to be soft; this condition can also be known as rickets.
The best sources of calcium are:
- dairy products such as milk, cheese and yogurt – low-fat ones are best, and it doesn't matter if they come from cows or other animals, for example goats
- calcium-enriched milks made from soya, rice or oats
- fish that are eaten with the bones (such as tinned sardines).
Skimmed and semi-skimmed milk contains more calcium than full-fat milk.
We recommend a daily intake of calcium of 1,000 milligrams (mg), with added vitamin D if you’re over 60. If you don't eat many dairy products or calcium-enriched foods, then you may need a calcium supplement.
Recently there have been worries that taking calcium supplements (but not vitamin D) might have a negative effect on heart health. This seems to apply only to calcium tablets, not calcium from food. Increase the calcium you get from your food or talk to your doctor or a dietitian if you're worried.
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 conditions called osteoporosis or osteomalcia (see above).
Other than bone health, vitamin D is thought to also:
- help you have healthy muscles
- boost your immune system (your body's self-defence mechanism)
- reduce your chances of getting 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.
Iron is important in preventing anaemia, which is quite common in people with arthritis. The two main causes are:
- side-effects of taking non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen or diclofenac. Stopping the NSAIDs or taking another drug alongside them to protect the stomach (a proton pump inhibitor) may fix the anaemia, but taking iron supplements in the meantime will replace the iron your body lost through taking the NSAIDs.
- anaemia of chronic disease, which often occurs with rheumatoid arthritis and similar conditions and doesn’t improve with iron supplements.
If you’re anaemic your doctor can tell you if more iron is likely to help.
Good sources of iron are:
- red meat
- oily fish, for example sardines
- pulses, for example lentils and haricot beans
- dark green vegetables, for example spinach, kale and watercress.
Your body absorbs iron better if you take it with vitamin C, so have fruit juice or a good portion of fruit or vegetables with your meal. It’s best not to drink tea with your meal as this reduces the amount of iron that your body can absorb.
Poor vitamin C intake has been linked with arthritis. However, if you make sure you have your five portions of fruit and vegetables a day, you’re unlikely to have a problem with vitamin C and shouldn’t need supplements.
Mild selenium deficiency is quite common in the UK and may be linked with arthritis progressing more quickly. The richest natural source of selenium is Brazil nuts, but meat and fish also contain some. Selenium is nearly always included in antioxidant supplements.
Recent research suggests that taking high doses of selenium in the long term may be harmful, so you should keep to the recommended daily intake if you take selenium supplements over a long period. However, current evidence suggests that selenium supplements aren’t very effective in treating people with arthritis.