“ There is a growing interest in the role of modifiable lifestyle factors for their potential effects on MS risk and progression,” Steve Simpson-Yap, PhD, MPH, explains. “Of these, diet has garnered a significant interest in both the MS space and in other areas of health. A number of studies have implicated diet, as measured by overall diet quality, particular patterns of food intake, and individual foods and beverages, as potentially associated with aspects of health and wellbeing in MS, including disability, relapse rate, depression, and QOL.”

For a study published in the European Journal of Neurology, Dr. Simpson-Yap and colleagues examined the link between diet and disability, fatigue, and depression risk among individuals with MS. The researchers analyzed participants in the Health Outcomes and Lifestyle In a Sample of people with Multiple Sclerosis (HOLISM) international cohort for 2.5 years. Dietary data were gathered with a modified Diet Habits Questionnaire (DHQ), disability with the calculated Patientdetermined MS Severity Score (P-MSSS), fatigue with the Fatigue Severity Scale, and depression risk with the Patient Health Questionnaire-2.

Diet Impacts Disability Progression

Among 2,466 participants in the baseline HOLISM cohort, 1,346 with baseline DHQ data completed the 2.5-year survey and were included in the study.

In total, 14.1% screened positive for depression risk, and the median duration since onset was 14.0 years. More than 60% of patients reported eating meat and nearly 60% reported eating dairy.

“For our change in disability analysis, we found that higher-quality diet was associated with much lower disability progression 2.5 years later,” Dr. Simpson-Yap notes. “Those in the top two quartiles of Diet Habits Questionnaire (DHQ; >80%- 89% and >89%-100%) had 51% and 44% lower risk of their disability increasing over the next 2.5 years than people with the lowest DHQ score (32%-70%), with both associations persisting on adjustment for demographic and clinical factors. At the same time, participants who reported consuming meat at baseline had 86% higher risk for increasing disability during the next 2.5 years, with this also persisting on adjustment. Dairy consumption at baseline was associated with 47% higher risk for increasing disability over the next 2.5 years, but this association did not remain statistically significant on adjustment.”

The change in continuous disability analysis showed that participants in the top two quartiles of baseline DHQ score (>80%-89% and >89%- 100%) had 0.31 and 0.27 less disability progression per year, respectively, than those in the lowest DHQ quartile (32%-70%), with both findings persisting on adjustment, according to Dr. Simpson-Yap. Additionally, participants who reported consuming meat and dairy at baseline had 0.19 higher disability progression per year during the next 2.5 years of follow-up, with both findings persisting on adjustment.

More Diet & Depression Research Needed

Results of the current study, coupled with findings from previous research by Dr. Simpson-Yap and colleagues, indicate that “better diet quality is not causing lower depression, but rather, people with less depression are just more likely to consume a higher-quality diet,” he notes (Table).

“It is also possible that the nature of how we assessed diet quality and how we assessed depression may limit our ability to evaluate these very complex constructs,” Dr. Simpson-Yap says. “We merely say that, subject to replication in other settings, people with MS seeking to improve their mood and reduce depression risk may realize better outcomes by multiple avenues, both lifestyle modification and otherwise.”

Qualitative research that examines patients’ and caregivers’ beliefs about diet and its potential impact on MS would also be beneficial, according to Dr. Simpson-Yap.

“Neurologists and other medical professionals are somewhat reluctant to make recommendations to their patients about improving their diet beyond standard medical recommendations,” he says. “It would be worthwhile to get a better picture of how neurologists and other MS medical professionals discuss diet and other aspects of lifestyle with their patients, how they react and advise when patients say they want to modify their diet to improve their MS, and what ways they can most efficiently, but accurately, advise their patients about the potential MS and nonMS benefits of improved diet quality on their health and well-being.”