Healthy eating appears to be linked with reduced disability in people with all types of MS, according to analysis of their self-reported dietary habits and disability levels, researchers found.
A large cross sectional survey of almost 8,000 people with MS in the North American Research Committee on MS (NARCOMS) Registry found that, compared to people with the least healthy diet, those with the healthiest eating habits had 20% lower risk for severe versus mild disability (P=0.002 for trend), according to Kathryn C. Fitzgerald, ScD, of Johns Hopkins School of Medicine in Baltimore, and colleagues.
The researchers also found 18% lower risk for severe versus mild depression after adjusting for disability status (P=0.01 for trend), they reported online in Neurology.
Respondents were divided into five groups based on their 2015 responses on the dietary screener questionnaire (DSQ). The healthiest diet included more fruits, vegetables, legumes and whole grains, less sugar in desserts and drinks, and less red meat and processed meat. Dairy was not included due to its differing health effects, due for instance to saturated fat content. Results were significant after controlling for health-related factors such as age, MS duration, body mass index, income, and smoking.
Past or current exposure to any of 19 special diets, including MS-specific (Swank, Wahls) and popular diets (Mediterranean, Paleo, gluten-free) was associated with a modest 11% reduction in the odds of increasing disability (P=0.009).
"People with MS often ask if there is anything they can do to delay or avoid disability, and many people want to know if their diet can play a role, but there have been few studies investigating this," said Fitzgerald.
"While this study does not determine whether a healthy lifestyle reduces MS symptoms or whether having severe symptoms makes it harder for people to engage in a healthy lifestyle, it provides evidence for the link between the two," Fitzgerald noted.
Relative benefits were even more marked in people with an overall healthy lifestyle – those who maintained a healthy diet and a healthy weight (<25 BMI), engaged in regular physical activity, and did not smoke had 55% lower odds of severe versus mild disability (P<0.0001) than those who did not have an overall healthy lifestyle, and this effect persisted (with 17% lower odds, P=0.008) after physical activity was excluded from overall lifestyle factors to control for possible effects of disability on activity levels.
Compared to people who did not practice a healthy lifestyle, those who did also reduced their odds of severe versus mild depression by 47%, pain by 44%, fatigue by 31%, cognitive symptoms by 34%, after adjusting for disease duration, Patient-Determined Disease Steps (PDDS), age, and sex.
In contrast, diet quality alone was not associated with severity of fatigue, pain, or cognitive symptoms, nor with relapse within the previous 6 months, or gradual symptom worsening.
Responders, who represented one-third of the NARCOMS database, were Caucasian (92%), married (42%), an average of 59.5 years of age), had been living with MS for an average of 20 years, and had an average PDDS of 3. About 55% had relapsing remitting MS, about 23% had secondary progressive MS, and less than 10% had primary progressive MS.
This highlights a response bias: compared to nonresponders from the NARCOMS population, responders were older, with longer disease duration and were more likely to be Caucasian, married, and of higher income.
Many MS patients ask about diet, said Elisabeth Lucassen, MD, of Penn State University's Hershey medical campus, who was not involved in the study.
"The bonus of this study is its assessment of general trends in the large sample provided by NARCOMS database," she told MedPage Today. The downside is that it is retrospective, there is selection-bias, reports are based on patients' accounts of what they ate (so may not be that accurate), and causality cannot be assumed."
In an accompanying editorial, James Sumowski, MD, of Mount Sinai Hospital in New York City, and two colleagues noted that on separate analysis, the only component of the diet score reliably linked to lower disability was higher intake of whole grains (1.7 versus 0.3 average servings/day). Highest versus lowest intake of fruits, vegetables, and legumes (excluding French fries) was 3.3 versus 1.7 servings per day.
They lauded the "convincing observational link between diet and disability," though they also noted the lack of investigation of "fish intake, with the interesting link to vitamin D, as a potentially important dietary factor."
Findings reflect the current belief that "diets rich in vegetables, fruit, legumes, fish, prebiotics/probiotics help upregulate oxidative metabolism, downregulate the synthesis of proinflammatory molecules, and promote a healthy symbiotic gut microbiota," Lucassen noted.
Cautioning that the study design limits causal inferences, Fitzgerald told MedPage Today, "In addition to these [above] hypothesized biological mechanisms that have been linked with MS, previous studies have also shown that people with MS are at an increased risk of several cardio-metabolic comorbidities (like hypertension, high-cholesterol) and that having them may adversely affect MS outcomes. Other studies have shown that eating a healthy diet lowers risk of these comorbidities. So, it's possible that a healthy diet may impact MS-disability through its beneficial effects on cardio-metabolic risk."
The next important but challenging steps are to perform randomized controlled trials of diet to yield causal evidence for dietary interventions, wrote Sumowski and colleagues, noting that pilot studies have been completed or are underway.
This work was supported by the Consortium of multiple sclerosis Centers (CMSC) and the Foundation of the CMSC.
Fitzgerald disclosed research funding from the Consortium of MS Centers and the National MS Society; several coauthors disclosed relationships with industry.
Editorialist Sumowski has worked as a consultant for Genzyme; his co-authors declared they had nothing to disclose.
last updated 12.08.2017
Source : https://www.medpagetoday.com/neurology/multiplesclerosis/69725