Vitamin D is the only vitamin whose routine supplementation in multiple sclerosis (MS) patients is backed by evidence, according to a systematic review published in JAMA Neurology.
“Despite the existence of 15 currently approved disease-modifying therapies, most patients with MS still experience disability accrual and persistent symptoms, highlighting the need for adjunctive therapies,” wrote authors led by Anne H. Cross, MD, John L. Trotter MS Center, Department of Neurology, Neuroimmunology Section, Washington University in St Louis, St. Louis, MO. “Vitamins and dietary supplements are being increasingly explored to address this unmet need.”
Previous surveys have shown that the majority of patients with MS are highly interested in using dietary supplements, with more than half of these patients already taking them. The authors of the current review assessed the biological plausibility, human-trial data, safety concerns, and animal-model data for each vitamin and other type of supplement. Specifically, they looked at the following:
- Vitamin A
- Vitamin B1
- Vitamin B2
- Vitamin B3
- Vitamin B5
- Vitamin B6
- Vitamin B7
- Vitamin B9 and Vitamin B12
- Vitamin C
- Vitamin D
- Vitamin E
- Vitamin K
- Coenzyme Q
- Ginkgo biloba
- Green tea extract
- Lipoic acid
- Polyunsaturated fatty acids
Of all these supplements and extracts, only vitamin D has proven effective in studies. Vitamin D is actually a prohormone that is hydroxylated twice: once in the liver and once in the in various tissues. The double-hydroxylated 1,25-hyrdroxyvitamin D binds the vitamin D receptor and makes its way into the cell nucleus. In the nucleus, it binds vitamin D response elements on DNA, thus changing transcription rates of several MS-linked genes.
“Increased incidence of MS with increased distance from the equator, along with the main source of vitamin D being skin production on exposure to sunlight, supports a potential association between risk of MS and vitamin D levels,” the investigators wrote.
The authors cited several studies supporting the routine supplementation of vitamin D in MS patients, with more large-scale trials on the horizon. For example, researchers of the Nurses’ Health Studies found a decreased risk of MS with either a higher intake of vitamin D in the diet or supplementation of > 400 IU/d. Furthermore, in another prospective cohort study involving 145 MS patients, researchers discovered a linear dose-dependent decrease in the frequency of MS relapses that was significantly linked to 25-hydroxyvitamin D levels.
Of note, the upper limit for vitamin D supplementation is 4000 IU/d, with toxicity resulting in hypercalcemia, cardiac arrhythmias, and kidney stones.
Importantly, because the supplementation industry is loosely regulated in the United States, and the risk of receiving adulterated products is palpable, the reviewers suggest that people buy only dietary supplements stamped with United States Pharmacopeia (USP) designation. This designation ensures that the supplement is dispensed in the promised amount, absorbable, and devoid of impurities.
“At the present time, the only vitamin with sufficient evidence to support routine supplementation for patients with multiple sclerosis is vitamin D,” the researchers concluded. “Vitamin deficiencies should be avoided. It is important for clinicians to know which supplements their patients are taking and to educate patients on any known efficacy data, along with any potential medication interactions and adverse effects of individual supplements.”