BY SARAH OWENS
A healthy diet high in fruits, vegetables, and whole grains and low in red meat and added sugars, combined with a healthy lifestyle defined by a healthy body mass index (BMI) and routine exercise, was associated with lower disability and reduced symptom burden in patients with multiple sclerosis (MS), according to a study published online on December 6 in Neurology.
While the current findings from a cross-sectional study do not prove causality, the robust associations observed in a large population suggest that patients with MS "who maintain a healthier lifestyle have a lower prevalence of severe depression, pain, fatigue, and cognitive problems," the study authors, led by Kathryn C. Fitzgerald, ScM, of the Harvard School of Public Health in Boston, MA, wrote.
For the study, researchers assessed data on 7,639 participants in the North American Research Committee on MS Registry. The patients also provided demographic information as well as information on their health, including their smoking status, alcohol intake, physical activity, and their height and weight (used to calculate BMI).
Participants reported whether they had experienced an MS relapse or a gradual worsening of symptoms in the previous six months. They reported their level of disability using the Patient-Determined Disease Steps (PDDS), a scale of MS disability that strongly correlates with clinician-assessed measures such as the Extended Disability Status Scale.
In addition,the participants completed a dietary screener questionnaire (DSQ), a 26-item questionnaire that collects information on dietary intake for different food groups, including fruits, vegetables, legumes, dairy/calcium, added sugars (including those from sugar-sweetened beverages and dessert foods), whole grains/fiber, and red/processed meat. The DSQ applies age- and sex-adjusted scoring algorithms to patients' responses into estimates of total dietary intake for each category. The researchers then constructed an overall diet quality score for each participant based on these food groups, with higher scores denoting a healthier diet.
Finally, the researchers developed standards for a composite healthy lifestyle, defined as maintaining a healthy weight (BMI <25), routine physical activity (defined as running, calisthenics, golf, gardening, or walking in the last month), abstaining from smoking, and consuming a better-than-average diet (>median diet quality score).
The researchers adjusted for age, sex, income, BMI, smoking status, and disease duration.
They found that participants with diet quality scores in the highest quintile had lower levels of disability (PDDS; proportional odds ratio [OR] for Q5 vs Q1 0.80; 95% confidence interval [CI] 0.69–0.93) and lower depression scores (proportional OR for Q5 vs Q1 0.82; 95% CI 0.70–0.97) compared to patients in the lower quintiles. In addition, they found that patients who reported a composite healthy lifestyle had lower odds of reporting MS symptoms, including severe fatigue (0.69; 95% CI 0.59–0.81), depression (0.53; 95% CI 0.43–0.66), pain (0.56; 95% CI 0.48–0.67), or cognitive impairment (0.67; 95% CI 0.55–0.79).
Given that diet and lifestyle are modifiable, the study authors concluded, they "offer a promising, safe avenue to ameliorate MS-associated symptoms and influence the disease course."
In an editorial accompanying the study, James F. Sumowski, PhD, associate professor of neurology at the Mount Sinai Health System in New York; Gavin V. McDonnell, MD, FRCP, neurologist at Belfast Health and Social Care Trust; and Dennis Bourdette, MD, FAAN, the chair and Roy and Eulalia Swank Family Research Professor at Oregon Health and Science University wrote that the study "adds substantive and robust empirical data" to support the benefit of a healthy diet for patients with MS. However, they noted that the study's cross-sectional design prevented the researchers from determining causality, and randomized controlled trials testing the benefits of specific dietary interventions are needed.
The study authors acknowledged that the cross-sectional nature of their study prevented them from making causal inferences. They noted a number of other limitations, including that the study population lacked diversity, and the DSQ lacked detailed information on "potentially important dietary factors," including different types of fats and dairy foods.
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