Effect of the Swank and Wahls Elimination Diets on Perceived Fatigue and Cognitive Dysfunction in Relapsing-Remitting Multiple Sclerosis: A Randomized Parallel-Arm Trial

Background: The Swank and Wahls Elimination (Wahls) dietary patterns are popular in the multiple sclerosis (MS) community but there is limited data regarding their effect on fatigue and cognitive dysfunction from randomized clinical trials.

Objectives: To evaluate the impact of both diets on secondary outcomes of perceived fatigue and cognitive disfunction within and between the diet groups among individuals with relapsing-remitting MS (RRMS).

Methods: Individuals (n = 95) with RRMS were randomized to either the Swank or Wahls diets in a 36-week randomized, parallel group clinical trial consisting of a 12-week run-in followed by a 24-week intervention. After the 12-week run-in, participants were randomized and provided study diet specific materials and education by registered dietitians. From baseline to 12 weeks, the registered dietitians provided active support to study participants but did not continue support from 12- to 24-weeks. The Fatigue Scale for Motor and Cognitive Functions (FSMC) and Perceived Deficits Questionnaire (PDQ) were collected at four timepoints: 1) run-in, 2) baseline, 3) 12 weeks, and 4) 24 weeks. The outcomes were analyzed using general linear mixed models to assess changes within and between groups over time using demographic and clinical control variables.

Results: There was no difference in baseline demographic or clinical characteristics (including FSMC and PDQ) between diet groups, with 77 participants completing 12 weeks and 72 completing 24 weeks. Both groups experienced significant mean (±SEM) reductions in total FSMC at 12- and 24-weeks (Swank, -5.7 ± 1.7 and -9.0 ± 2.4, respectively; Wahls, -9.3 ± 2.0 and -14.9 ± 2.5, respectively; P ≤ 0.001 for all). Similarly, both groups experienced significant reductions in total PDQ at 12- and 24-weeks (Swank, -7.4 ± 1.7 and -6.3 ± 1.7, respectively; Wahls -6.8 ± 2.0 and -10.8 ± 2.2, respectively; P ≤ 0.001 for all). Analysis of the mental and physical FSMC and the attention, retrospective memory, prospective memory, and planning PDQ subscales demonstrated similar patterns. There were no differences between groups in absolute mean FSMC, PDQ, or their subscale values at any time point.

Conclusions: The Swank and Wahls diet groups demonstrated significant reductions in perceived fatigue and cognitive dysfunction scores at 12- and 24-weeks. Future large randomized controlled dietary intervention trials should include measures of fatigue and cognitive dysfunction.