What are vitamins A, C and E?
Vitamins A, C and E are essential nutrients which have antioxidant activity. Laboratory and animal studies have found some scientific basis for their use, but current evidence from studies on humans suggests that antioxidant vitamins aren’t effective in treating rheumatoid arthritis. Evidence from trials of the effectiveness of vitamin E in treating osteoarthritis provided mixed results. Results for early trials into the use of vitamin C in treating osteoarthritis are encouraging, but they need confirmation by larger trials.
- Family: Nutritional supplement
- Scientific name: Vitamin A (retinoids), vitamin C (L-ascorbate) and vitamin E (tocopherols and tocotrienols)
Vitamins are nutritional substances which you need in small amounts in your diet. Vitamins A and E are fat-soluble vitamins, meaning they’re stored in your body’s fat cells, but they need to have their levels topped up regularly. Vitamin C is a water-soluble vitamin. Your body stores all water-soluble vitamins except for vitamin B12 for only a brief period of several weeks to several months and then gets rid of them through the urine. This is why you need to take water-soluble vitamins daily.
Vitamins can be found in foods (natural vitamins) or can be produced in laboratories (synthetic vitamins). You can buy vitamin capsules from high-street shops.
How do they work?
Vitamins A, C and E have antioxidant properties. This means they can override harmful molecules, known as free radicals, which are produced within your cells and which may cause tissue damage or disease. Your body produces its own antioxidants but it’s thought that antioxidants in the diet (such as vitamin C) help destroy excess free radicals.
Some laboratory and animal studies have also found that vitamin E may help to treat osteoarthritis by stimulating the growth of cartilage cells. Other studies have found that it has some anti-inflammatory properties.
Studies on vitamin C have found that it can stimulate the production of collagen and proteoglycan (both of which are important parts of joint cartilage) and can protect against the breakdown of cartilage in animal studies.
Are they safe?
Vitamin C is considered to be a very well-tolerated vitamin because if your body can get rid of it through the urine if has too much.
Because your body stores vitamins A and E, having too much of these vitamins can cause health problems. If you take more than 50,000 international units (IU) of vitamin A over a long period, it can cause vitamin A toxicity. Symptoms of this can include:
- dry skin or rashes
- bone pain
- hair loss
- sleep problems
- gastrointestinal problems.
Most adults can tolerate up to 100–800 mg a day of vitamin E, but long-term intake of large doses (more than 1,000 mg daily) can cause headaches, nausea, blurred vision and disturbed functions of the thyroid gland. Recently, it has been recommended that high-dose intake of vitamin E (more than 400 mg a day) should be avoided.
We don’t yet have recommended effective and safe doses for use in arthritis and related conditions. Most trials used daily doses of 1,200 mg vitamin E, 50,000 IU vitamin A and 1,000 mg vitamin C.
No serious drug interactions have been reported with a low or medium intake of antioxidant vitamins.
Trials for rheumatoid arthritis
Three of the four trials in this review article investigated the potential role of vitamin E in treating rheumatoid arthritis, while the fourth studied the effectiveness of selenium ACE treatment.
- In the first trial‡ (42 people over a 12-week period), there was no significant difference between participants on 1,200 mg per day vitamin E supplements or a placebo in morning stiffness, number of swollen joints and degree of joint tenderness, but there was a significant difference in pain reduction in favour of participants taking vitamin E.
- In both the second trial (41 people over a three-week period) and the third trial (85 people over a three-week period), there was no significant difference between participants allocated 1,200 mg a day vitamin E supplements or participants given 150 mg diclofenac (a non-steroidal anti-inflammatory drug) a day in all aspects of disease severity at the end of the trial.
- In the fourth trial‡ (20 people over a six-month period), there was no significant difference between participants who received selenium ACE supplements or participants on a placebo in all aspects of disease severity at the end of the trial.
‡ A trial of low quality. Results of this trial were given a lower weighting when we came to our conclusion about the compound.