Evaluating the Effects of Dietary Interventions on Disease Progression and Symptoms of Adults with Multiple Sclerosis: An Umbrella Review.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system. The role of diet in the progression of MS and severity of symptoms remains unclear. Various systematic literature reviews (SRs) have reported the effects of single nutrients on MS progression or the role of dietary factors on specific symptoms of MS. Narrative reviews have examined the effects of various dietary patterns in MS populations. An umbrella review was undertaken to collate the findings from review articles and evaluate the strength of the scientific evidence of dietary interventions for people living with MS. Scientific databases including MEDLINE, PubMed, CINAHL, and The Cochrane Library were systematically searched up to April 2019. Review articles and meta-analyses were included if they examined the effect of any dietary intervention in adult populations with MS. Outcomes included MS progression indicated by relapses, disability, MRI activity and disease classification, and MS symptoms. Characteristics and findings from both review articles and their included primary studies were extracted and summarized. A total of 19 SRs and 43 narrative reviews were included. Vitamin D and PUFAs were the most commonly studied interventions. Across SR studies, vitamin D supplementation had no significant effect on relapses, MRI, or disability progression; however, an inverse association was found between vitamin D status and disability scores through observational studies. Effects of PUFA supplementation on major outcomes of MS progression were inconsistent across review articles. Other interventions less commonly studied included vitamin, mineral, and herbal supplementation and varying dietary patterns. Strong consistent evidence is lacking for dietary interventions in persons with MS. The body of evidence is primarily focused around the isolation of individual nutrients, many of which demonstrate no effect on major outcomes of MS progression. Stronger food-focused studies are required to strengthen the evidence.