Mediterranean-like diets in multiple sclerosis: A systematic review

Mediterranean-like diet is an anti-inflammatory diet with high-fiber consumption and lower intake of saturated fatty acids which is proposed to have beneficial effects in patients with multiple sclerosis (MS). This investigation aims to explore the impacts of this style of diet on people living with MS, based on clinical evidence. This study was conducted following the 2020 version of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Both interventional and observational clinical studies which evaluated the effects of Mediterranean-like diets on MS patients were considered for inclusion. Review articles, letters, commentaries, case reports, non-English papers, and conference abstracts were excluded. PubMed, Web of Science, Scopus, and EMBASE databases were searched until March 23rd, 2023, and risk of bias in randomized-controlled trials (RCTs) was evaluated based on the second version of the Cochrane RoB assessment tool (RoB.2). In addition, for the observational studies, Joanna Briggs Institute (JBI)’s critical appraisal tools were utilized. Of 161 records that were screened in the title/abstract stage, 13 reports of 11 studies were included in the systematic review. Three RCTs (including one pilot RCT), and eight observational studies reported the effects of Mediterranean-like diets on people living with MS. The sample sizes in clinical trials varied between 36 and 147 and for observational studies between 30 and 563 patients. Evidence suggested positive effects of a Mediterranean-like diet on inflammatory status and MS-related symptoms such as fatigue, quality of life, attack rate, and cognitive dysfunction. This systematic review pointed out possible beneficial effects of Mediterranean-like diets for MS patients. The limited number of well-designed RCTs was the main limitation of this study; therefore, large-scale multiple-center interventional studies are suggested. Variety in the assessed outcomes, study designs, and groups of the studies prevented meta-analysis which was the other limitation of this study.