Friday, March 22, 2013. The results of a double-blind, placebo-controlled trial reported online on March 13, 2013 in the American Journal of Clinical Nutrition reveal a benefit for vitamin D supplementation in men and women with Parkinson's disease.
In their introduction to the article, Masahiko Suzuki and his colleagues at Jikei University School of Medicine in Tokyo note that vitamin D levels are lower in Parkinson's disease patients. Supplementation with the vitamin has been found to reduce the risk of falling, which is higher among individuals with the disease. Studies have shown that variations in the vitamin D receptor gene are associated with Parkinson's disease risk.
For the current trial, 114 Parkinson's disease patients were randomized to receive 1200 international units (IU) vitamin D3 per day or a placebo for twelve months. Hoehn and Yahr stage, Unified Parkinson's Disease Rating Scale, Parkinson's Disease Questionnaire-39 and other tests were administered to assess disease status before and after treatment. Blood samples collected at enrollment were analyzed for factors that included 25-hydroxyvitamin D and calcium levels, and variations in genes associated with vitamin D binding protein and vitamin D receptor.
By the end of the study, Parkinson's disease stage worsened on average among those who received the placebo, but was essentially unchanged among those who received vitamin D. United Parkinson's Disease Rating Scale scores were similarly unchanged among vitamin D-supplemented participants, but worsened in the placebo group. Total Parkinson's Disease Questionnaire-39 scores improved on average among those who received vitamin D but were essentially unchanged among those who received the placebo. A significant benefit for vitamin D3 was observed among subjects with either of two vitamin D receptor FokI genotypes, but not among those with a third FokI genotype.
"To the best of our knowledge, this is the first randomized trial to examine the effects of vitamin D3 in patients with Parkinson's disease," the authors announce. "However, a meta-analysis showed that supplemental vitamin D for older adults who participated in randomized controlled trials consistently showed beneficial muscle effects on strength and balance. Therefore, it cannot be distinguished whether vitamin D supplementation specifically delays the progression of Parkinson's disease or whether it just nonspecifically improves muscle strength and balance in older adults."
The authors observe that the dose of vitamin D3 used in the study may have not been enough to maximize the effect of supplementation to improve Parkinson's disease, and that the number of participants may have been too few to detect small differences in some endpoints. However, they remark that "Even with these limitations, vitamin D prevented the deterioration of Parkinson's disease in this study."