However, conclusions on the recommended dosage to be used could not be reached due to study heterogeneity in relation to vitamin D quantities administered.
The Spanish researchers emphasise the significance of their ‘Nutrients’ published findings: “To our knowledge, this is the first systematic review with meta-analysis that synthesized the effects of [vitamin D] supplementation in relation to fatigue, a symptom that affects most people with this disease. Our data show a significant reduction in fatigue in those who received VD supplementation compared to the control group.”
“This systematic review and meta-analysis suggests that supplementation with VD might have a significant effect on reducing fatigue in people with MS,” they conclude.
Vitamin D and disease
The autoimmune and inflammatory disease of MS is a leading cause of disability among young adults, resulting in a range of symptoms including balance blurred vision, cognitive decline, and fatigue; which is known to be the most common suffered adversity.
Fatigue in those with MS can be defined as central fatigue affecting the nervous system, causing inflammation, demyelination and/or neurodegeneration, as well as peripheral fatigue which relates to dysfunctions of other bodily systems. In addition, fatigue can affect quality of life through the reduction of physical activity, concentration, and memory, whilst increasing the risk of anxiety and depression.
Whilst there have been a number of drugs developed to treat MS-related fatigue, the evidence to suggest their efficacy is limited. Therefore, there is significant interest in developing effective alternative treatments.
In addition to potential genetic and environmental causative factors, it has been highlighted that there may be a link between MS prevalence and limited UV radiation exposure, and thus, sub-optimal vitamin D levels. Therefore, the present meta-analysis and systematic review was conducted to investigate the effect of vitamin D and fatigue within MS sufferers.
The researchers reviewed the available literature within the scientific databases of MEDLINE, Cochrane Library, Embase and Web of Science, using determined inclusion criteria. Five RCTs assessing pre-post changes in fatigue following vitamin D supplementation were included within the review, which included 345 subjects aged 25-41 years old.
Following the calculation of effect sizes and 95% confidence intervals with a random effects model, it was noted that vitamin D supplementation resulted in a significant reduction in perceived fatigue when compared with a control group.
Yet, an optimal dose and duration of treatment was not determined, due to significant study variation of supplement administration.
Thus, the findings suggest that vitamin D supplementation may be an effective dietary intervention strategy for reducing fatigue symptoms in those suffering from MS.
Explaining the mechanism of action behind this effect, the authors explain: “Vitamin D appears to have an immunomodulatory effect that includes the activation and proliferation of lymphocytes, the differentiation of T cells, and a reduction in inflammatory cytokines.”
The report notes: “It has been observed that suboptimal levels of VD can contribute to inflammation and axonal degeneration in people with MS.”
However, the researchers emphasise the importance of further study utilising greater levels of control to understand the optimal dose and duration of treatments.
“Effect of Vitamin D Supplementation on Fatigue in Multiple Sclerosis: A Systematic Review and Meta-Analysis”
by Purificación López-Muñoz, Ana Isabel Torres-Costoso, Rubén Fernández-Rodríguez, María José Guzmán-Pavón, Sergio Núñez de Arenas-Arroyo, Julián Ángel Basco-López and Sara Reina-Gutiérrez