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

Abstract

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.

Keywords: MS; anxiety; cognitive function; depression; diet; disability; fatigue; magnetic resonance imaging; nutrition; relapse.

FIGURE 1

PRISMA flow diagram for the umbrella review addressing MS and diet. MS, multiple sclerosis; NR, narrative review; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; SR, systematic literature review.

FIGURE 2

Categorization of primary study designs examining MS progression and symptoms in relation to diet. MS, multiple sclerosis; PUFA, polyunsaturated fatty acids.

FIGURE 3

Proportion of primary studies examining the effect of dietary supplementation, dietary intake, and nutritional status on outcomes of MS progression and symptoms. MS, multiple sclerosis.

FIGURE 4

Designs of primary studies included within all review articles addressing MS and diet. MS, multiple sclerosis.

FIGURE 5

Findings of primary studies across all review articles examining the effect of vitamin D supplementation on outcomes of MS progression and symptoms. MRI, magnetic resonance imaging; MS, multiple sclerosis.

FIGURE 6

Findings of primary studies across all review articles examining the effect of serum vitamin D status on outcomes of MS progression and symptoms. MIRRI, megnetic resonance imaging; MS, multiple sclerosis.

FIGURE 7

Findings of primary studies across all review articles examining the effect of fatty acid intake on MS relapses and disability progression. MS, multiple sclerosis; PUFA, polyunsaturated fatty acids.

FIGURE 8

Findings of primary studies examining the effect of vitamin supplementation and serum vitamin levels on disability scores for MS. Disability measured using the EDSS. B-12, vitamin B-12; EDDS, Expanded Disability Status Scale; MS, multiple sclerosis.