Background: Diet has been associated with the onset and progression of multiple sclerosis (MS). Multiple diets, varying in recommendations, have been proposed as beneficial to people with MS. The characteristics of those who follow specific diet-programs and the relationships of these diet-programs with diet quality is under-explored.

Methods: Data from the HOLISM study were analysed. Adherence to selected MS-specific diets (Ashton Embry Best Bet, McDougall, Overcoming MS (OMS), Palaeolithic, Swank, and Wahls Elimination) were each queried on 5-point Likert scales, and moderate (≥3/5) and rigorous (≥4/5) adherence defined. Sociodemographic and clinical characteristics of adherence were evaluated by log-binomial regression. Relationships of diet-program adherence with diet quality as measured by Diet Habits Questionnaire were assessed by linear and log-binomial regression, as appropriate, adjusted for age, sex, socioeconomic status (SES), education, and clinically significant fatigue.

Results: Forty-nine percent of participants reported at least 12-month adherence to a diet-program for their MS. Of these, 31.3% rigorously adhered to OMS, 4.9% to Swank, 1.7% to Wahls, and <1.5% to other diet-programs. Only adherence to any diet-program, OMS, Wahls, and Swank, were quantitatively assessed. Females, and participants of lower-than-average SES and longer disease duration were less adherent to any diet-program for MS, as well as those with higher disability, more clinically significant fatigue, greater depression risk, and more comorbidities. Those with higher-than-average SES were more adherent, as were those with higher physical and mental quality of life. Similar relationships were seen for OMS diet-program adherence. Adherence to Wahls diet-program was higher among those with progressive MS types and longer disease duration. No associations were found for adherence to Swank diet-program. Overall diet quality was higher among participants following any diet-program, particularly OMS and Swank, but not Wahls.

Conclusion: Greater adherence to MS specific diets was associated with higher SES, and higher quality of life. Following any diet program was associated with higher overall diet quality, with those adhering to the OMS diet having the highest diet quality. These results may inform health professionals in providing guidance to patients regarding diet in MS.