ORLANDO, Florida — A Paleolithic elimination diet (Wahls diet) or a low-saturated fat diet (Swank diet) are associated with improved cognition, among other clinical outcomes, in relapsing-remitting multiple sclerosis (RRMS), new research suggests.
In a randomized study of patients with RRMS, the group that followed a Wahls diet and the group that followed a Swank diet both showed significant, unique improvement in measures of cognitive dysfunction, fatigue, and quality of life.
“Several dietary intervention studies have demonstrated favorable results on MS-related fatigue and quality of life. However, these results are among the first to show favorable reductions in cognitive dysfunction,” co-investigator Tyler Titcomb, PhD, Department of Internal Medicine, University of Iowa in Iowa City, told Medscape Medical News.
The results were presented at the Consortium of Multiple Sclerosis Centers (CMSC) 2021 annual meeting.
Similar Diets
The CMSC findings came from a secondary analysis of a randomized trial published online in July in the Multiple Sclerosis Journal – Experimental, Translational and Clinical (MSJ-ETC).
The primary analysis of the single-blind, parallel group, randomized trial showed the Wahls and Swank diets were linked to significant improvement in outcomes on the Fatigue Severity Scale (FSS), the Modified Fatigue Impact Scale (MFIS), and other measures among participants with RRMS. There were no significant differences between the two dietary regimens.
The Swank diet restricts saturated fat to a maximum of 15 g per day while providing 20 g to 50 g (4 to 10 teaspoons) of unsaturated fat per day, with four servings each of whole grains, fruits, and vegetables.
The Wahls diet recommends six to nine servings of fruits and vegetables per day, in addition to 6 to 12 ounces of meat per day, according to gender. Grains, legumes, eggs and dairy, with the exception of clarified butter or ghee, are not permitted on this diet. Both diets eschew processed foods.
To further evaluate the diets’ effects in perceived fatigue and cognitive dysfunction, the researchers returned to the trial, which enrolled 95 adults with stable RRMS at the University of Iowa Prevention Intervention Center between August 2016 and May 2019.
After a 12-week run-in period with support and education from registered dietitians, participants were randomly assigned to either the Swank or Wahls diets in a 24-week intervention that did not include dietitian support.
Inclusion criteria included having moderate to severe fatigue, as shown by an FSS score of at least 4.0, while not having severe mental impairment, an eating disorder, or liver or kidney disease. There were no significant differences in baseline demographic or clinical characteristics between the groups.
Of the patients, 77 completed the 12-week run-in (38 in the Swank diet group and 39 in the Wahls group). A total of 72 participants completed the 24-week follow-up (37 and 35, respectively).
Reduction in Fatigue, Cognitive Dysfunction
After controlling for smoking, alcohol consumption, age, sex, baseline distance 6-minute walk test, body mass index, serum vitamin D, and years with MS, results at 12 and 24 weeks showed significant improvements from baseline in the key outcomes of fatigue and cognitive function, as measured by the Fatigue Scale for Motor and Cognitive Function (FSMC).
Scores were −5.7 and −9.0, respectively, for the Swank diet group and −9.3 and −14.9 for the Wahls group (P ≤ .001 for all comparisons).
In addition, there was a significant reduction in both groups on the total Perceived Deficits Questionnaire (PDQ) at 12 and 24 weeks (Swank, −7.4 and −6.3, respectively; Wahls, −6.8 and −10.8; P ≤ .001 for all).
There were similar improvements for both diets in an analysis of the mental and physical scores on FSMC and on the subscales on PDQ of attention, retrospective memory, prospective memory, and planning.
As observed in the primary analysis, there were no significant differences between the two groups in absolute mean scores on FSMC, PDQ, or their subscales at any timepoint.
“Both diets led to significant reductions in fatigue and cognitive dysfunction,” Titcomb said.
Of note, the primary analysis further showed statistically and clinically significant increases in the 6-minute walk test at 24-weeks of 6% in the Wahls group (P = .007). After removal of nonadherent participants, the improvement was still significant at 24 weeks in the Wahls group (P = .02), as well as in the Swank group (P = .001).
Titcomb noted that the majority of study participants were taking disease-modifying therapies (DMTs). However, there were no interactions between any specific DMTs and dietary benefits.
Potential Mechanisms
Although the similar outcomes between the diets point to a common mechanism, there are also various other possibilities, said Titcomb. These include modulation of the microbiome, inflammation, immune system, or micronutrient optimization, he said.
Previous research has shown reduced mass and diversity in the gut microbiota among patients with MS compared with those without MS, potentially promoting inflammation. Other research has shown improvements in those factors with dietary modification.
While there is no evidence of gut microbiota changes with the Wahls and Swank diets, each is rich in fiber and plant-derived phytochemicals, which are known to be associated with improvements in gut microbiota and neuroinflammation, the investigators note.
Titcomb reported that research into the diets is continuing as they evaluate longer-term and other effects.
“This trial was a short-term parallel arm trial that did not include MRI or a control group,” he said, adding that the investigators will soon start recruiting for a follow-up study that will include a control group, long-term follow-up, and MRIs.
That upcoming study “has the potential to answer several of the unknown questions regarding the effect of diet on MS,” Titcomb said.
Notable Research With Limitations
Commenting on the study for Medscape Medical News, Rebecca Spain, MD, MSPH, associate professor of neurology at the Oregon Health & Science University, and associate director of clinical care at VA MS Center of Excellence West in Portland, said there were several notable findings.
This includes that most people with MS “were able to adhere to the protocols for significant lengths of time, even without the support of dietitians for the final 12 weeks of the study,” said Spain, who was not involved with the research.
A significant limitation was the lack of a control group. Without that, “it’s hard to know for sure if the improvements in fatigue and cognition were from the diets or were simply from the social support of participating in a research study,” she said
Nevertheless, trials reporting on dietary effects in MS such as the current study are important, Spain noted. They demonstrate “that it is feasible and safe to conduct dietary studies, and suggest which key MS symptoms may benefit and should be evaluated in future studies.”
“Critically, diet studies address one of the most frequent concerns of people with MS, promoting self-management and empowerment,” Spain concluded.
General guidelines for common dietary elements with evidence of improving fatigue, cognition, and mood are available on the National MS Society’s website.
The study received no outside funding. Titcomb and Spain have disclosed no relevant financial relationships. Terry L. Wahls, MD, who developed the Wahls diet, was a senior author of the study.
Consortium of Multiple Sclerosis Centers (CMSC) 2021 Annual Meeting. Presented October 25, 2021.
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