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 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.
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.
Your body needs vitamin D to absorb and process calcium. It's not naturally present in many foods, although oily fish is a good source.
Vitamin D is sometimes called the sunshine vitamin because your body produces it when your skin is exposed to sunlight. Where possible, going outside and exposing your arms and face to sunlight is the best way to get vitamin D. From June to August just 15 minutes a day is generally enough. Don’t allow your skin to go red and take care not to burn, particularly in strong sunshine and if you have fair or sensitive skin. Dark skin needs more exposure, and more exposure is needed in winter.
Because of the lack of sunlight, slight deficiency is quite common in winter in the UK, especially in the north. There’s some evidence that arthritis progresses more quickly in people who don’t have enough vitamin D, and severe deficiency causes osteomalacia, so a supplement such as fish liver oil may be useful during winter months. However, it’s important not to take too much fish liver oil because it contains high levels of vitamin A.
If you're over 60, dark-skinned or don't expose your skin much to the sun and are worried about a lack of vitamin D, you and your doctor should discuss whether a vitamin D supplement would be right for you. It’s sometimes necessary to take a daily supplement containing 10–20 micrograms (μg), or 400 to 800 international units (IU), of vitamin D, especially for people over 60. You can buy them from chemists, supermarkets and health food stores. If you have severe deficiency, which is diagnosed through a blood test, you may need an injection or high-strength tablets.
Iron is important in preventing anaemia, which is quite common in people with arthritis. The two main causes are:
If you’re anaemic your doctor can tell you if more iron is likely to help.
- 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.
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.