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[2008 updates are highlighted in red]
| Description: |
Free radicals are chemicals that may injure cells in the body through a process known as oxidative damage. Antioxidants are compounds that can decrease oxidative damage. Commonly used antioxidants include selenium and vitamins A, C, and E. Other compounds in the antioxidant category include alpha-lipoic acid, inosine, uric acid, coenzyme Q10 (CoQ10), grape seed extract, pycnogenol, and oligomeric proanthocyanidins (“OPCs”). Antioxidants are sometimes specifically marketed as a treatment for MS. |
| Rationale: |
There are two major reasons that antioxidants are relevant to MS. First, free radicals may be involved in the pathology of MS. Myelin, the insulation of nerve fibres, may be injured in MS by the release of free radicals by immune cells. Also, the nerve fibres themselves, the axons, are damaged in MS through a degenerative process that may involve free radicals. Indeed, some studies indicate that oxidative damage is increased in EAE, the animal model of MS, and in tissue from people with MS. The other MS-relevant aspect of antioxidants is that diets that are enriched in polyunsaturated fatty acids, which are sometimes recommended for MS (see “Diets”), may cause vitamin E deficiency and supplementation with vitamin E may be needed. |
| Evaluation: |
Specific studies of antioxidants in MS are very limited. Studies in EAE, the animal model of MS, indicate that antioxidants may decrease disease severity. Recent studies have shown that alpha-lipoic acid and uric acid are effective therapies for EAE. In a human study, it was found that 18 people with MS who were treated for five weeks with vitamin C, vitamin E, and selenium did not experience any adverse effects. This study was too small and too short to provide any definitive results about the safety and effectiveness of antioxidants in MS. Clinical studies in people with MS are currently being conducted with alpha-lipoic acid and inosine, a compound that is converted to uric acid. |
| Risks: |
Many antioxidant compounds activate immune cells known as T cells and macrophages. Since these cells are already excessively active in MS, further stimulation by antioxidants could potentially worsen the disease. Whether this occurs and is clinically important in MS has not been investigated. Thus, it represents a theoretical risk. The safety of many dietary supplements, including antioxidants, has not been determined in women who are pregnant or breastfeeding. |
| Costs: |
Supplementation with antioxidants is a low-cost therapy. |
| Committee opinion: |
In the opinion of the Committee, there is theoretical and experimental evidence that antioxidants could be of therapeutic value in MS. However, there are no well-designed clinical studies that have addressed whether antioxidants are indeed effective or safe in MS. Further clinical studies of antioxidants in people with MS are needed and are currently underway. Antioxidants are inexpensive and are associated with theoretical risks in MS. |
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