Swank and Wahls diets seen to improve RRMS hand, arm dexterity

Sticking to either plan helped ease functional disability at 6 months: Study

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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An illustration shows a balanced, varied diet of fish, greens, beans, nuts and seeds, and fruits and vegetables.

The Swank and Wahls diets — two dietary strategies often adopted by people with multiple sclerosis (MS) — were similarly effective at easing functional disability after six months among people with relapsing-remitting MS (RRMS), according to data from a small clinical trial.

These functional gains were mostly driven by improvements in cognitive processing speed and hand and arm dexterity for patients on both diets. Yet, these gains were found to be mediated by changes in fatigue levels, which was the trial’s main outcome measure.

“This study provides preliminary evidence for the effect of dietary interventions on functional disability … in RRMS and shows that fatigue mediates this effect,” the researchers wrote.

With improvements seen with both diets, the team added that “the benefits of dietary intervention in MS are driven by similar diet components, allowing patients to choose to follow dietary patterns based on their individual preferences.”

The study, “Diet-induced changes in functional disability are mediated by fatigue in relapsing-remitting multiple sclerosis: A secondary analysis of the WAVES randomized parallel-arm trial,” was published in the Multiple Sclerosis Journal — Experimental, Translational and Clinical.

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Diet is believed to be a lifestyle factor that can influence MS risk and progression. An accumulating number of studies assert that a generally healthy diet, or particular diet regimens, could have benefits for people with the neurodegenerative disease. As a result, about half of MS patients report having modified their diet in some way, according to the authors.

However, there is not enough scientific evidence to support one specific MS diet. Data are lacking on whether particular dietary interventions truly affect MS symptoms and progression, particularly as it relates to functional disability.

The WAVES trial (NCT02914964), launched in 2016, was designed to compare the effects of two diets — Swank and Wahls, each named for its developer — that are popular in the MS community.

The Swank diet, probably the best-known one in MS, was created by Roy Swank, MD, PhD, in the 1940s. It’s essentially a low-fat diet that restricts intake of saturated and unsaturated fats and encourages the eating of fruits, vegetables, nonfat dairy, lean meats, and whole grains.

The Wahls diet, a newer plan developed by Terry Wahls, MD, herself an MS patient, is a modified version of the Paleo diet. It involves eating foods that would have been consumed in the Paleolithic era, thousands to millions of years ago. This dietary plan is comprised of meat, fish, and plant-based foods — fruits, roots, and nuts — while avoiding highly processed foods, grains, dairy, legumes such as soy, eggs, and nightshade vegetables. Tomatoes, potatoes, and peppers are among the vegetables to avoid.

WAVES is being conducted at the University of Iowa, led by Wahls. A total of 87 adult RRMS patients experiencing fatigue were assigned to either diet for 24 weeks, or about six months, after a 12-week (about three-month) control period in which everyone followed their usual diet.

Trial results indicated that patients in both groups experienced clinically significant reductions in fatigue and life quality gains regardless of diet. Among participants who adhered to their assigned diet, both plans were associated with significant improvements in exercise capacity, measured by the six-minute walk test (6MWT).

Now, the researchers are reporting on secondary outcomes from the WAVES trial related to functional disability measures, as assessed by the Multiple Sclerosis Functional Composite (MSFC), which takes into account performance on a few different functional evaluations.

This includes the Timed 25-Foot Walk Test (T25FW), which measures walking ability, the Nine-hole Peg Test (NHPT) that looks at manual dexterity, and the oral Symbol Digit Modalities Test (SDMT-O), an assessment of cognitive function.

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In general, both diets were found to reduce functional disability, with no significant differences between the two at any time point in MSFC scores or on any of its individual components.

Those in the Swank group saw statistically significant increases, meaning improvements, in MSFC scores from the trial’s start at weeks 12 and 24. At the second time point, average scores had improved 0.27 points. MSFC performance improvements were statistically significant in the Wahls group only at 24 weeks, with a mean increase of 0.18 points.

After 24 weeks, 8.3% of the Swank group and 8.8% of the Wahls group had met the threshold for a clinically significant improvement in MSFC, or at increase of least 0.5 points.

Both groups experienced significant improvements in NHPT and SDMT-O performance at 24 weeks, whereas T25FW scores were not changed in either group.

[The similar outcome with these diets] suggests that the potential effects of diet on functional disability are modulated by similar diet components rather than the unique composition of each diet.


Additional analyses showed that, when fatigue was taken into account, changes in MSFC and in its individual components lost significance in both dietary groups. This indicated that changes in fatigue were responsible for the effects of diet on functional disability.

Altogether, the similar outcome with the two diets “suggests that the potential effects of diet on functional disability are modulated by similar diet components rather than the unique composition of each diet,” the researchers wrote.

Indeed, both diets emphasize the intake of fruits and vegetables, and avoid processed foods. This also is consistent with the Mediterranean diet, which also has been linked to improved disability outcomes in MS.

According to the researchers, this may mean that patients can choose a diet with these commonalities based on their individual preferences, and still see benefits.

“Future well-designed randomized controlled trials … are needed to confirm these findings and better understand the clinical usefulness of dietary interventions for disability management among people with MS,” the team concluded.