A randomized controlled trial investigating the effects of a mediterranean-like diet in patients with multiple sclerosis-associated cognitive impairments and fatigue

Background: Among multiple sclerosis (MS) related symptoms and complications, fatigue might impact roughly 90% of patients. Decline in cognitive function is one of the other complications that occur in the first years after disease onset. The Mediterranean diet is one of the well-known anti-inflammatory dietary approaches. Therefore, this study aimed to explore the effects of a modified Mediterranean-like diet on cognitive changes and fatigue levels in comparison with a conventional standard diet over a 1-year follow-up. Methods: In the current single-blind randomized controlled trial, 34 MS patients in the Mediterranean- like diet group and 38 patients in the standard healthy diet group were studied for 1 year. The dietary interventions were modified each month by an expert nutritionist. MS-associated fatigue level was evaluated using the Modified Fatigue Impact Scale (MFIS). Cognitive assessment was also performed using Minimal Assessment of Cognitive Function in MS (MACFIMS). Results: Intergroup ‎comparisons demonstrated that after considering confounding variables in ANCOVA, fatigue scores appeared significantly lower in patients who were treated with the Mediterranean-like diet than those in the standard healthy diet group [Mean 95% confidence interval (CI)}: 33.93 (32.97-34.89) and 37.98 (36.99-38.97), respectively; P < 0.001]. However, the intergroup ‎analysis of cognitive status only showed a difference in the mean score of Brief Visuospatial Memory Test-Revised (BVMT-R) subtest of the MACFIMS. The BVMT-R‎ was higher among standard healthy diet patients compared to the Mediterranean-like diet group after the intervention following adjustment for covariates [Mean (95% CI): 23.73 (21.88-25.57) and 20.56 (18.60-22.51), respectively; P = 0.020]. Conclusion: In conclusion, the results of this study highlighted the higher protective effects of the Mediterranean-like diet against MS-related fatigue than the standard healthy diet. However, no significant improvement was observed in the cognitive status of MS patients after a 1-year treatment with the Mediterranean-like diet. More randomized clinical trials with larger sample sizes are needed to elucidate the effects of dietary modifications on MS-associated symptoms and complications.