Low-fat Vegan Diet May Reduce Fatigue But Doesn't Slow Down MS

Patient Expert

People who are newly diagnosed with MS are often interested in learning as much as possible about what they can do NOW to fight the disease. In addition to learning about MS and discussing disease-modifying therapy (DMT) with your neurologist, I frequently recommend that people focus on staying as healthy as possible through nutrition and exercise.

In addition to fighting MS with medication, patients may turn to diet, exercise, and alternative medicine to push back on the disease. Several studies have connected exercise to positive patient outcomes including reduced fatigue and improved cognitive function. But research exploring the effects of diet and nutrition on MS is less clear cut. A pioneer on the subject, Roy Swank, M.D., published several papers prior to 1991 discussing the benefits of a low-fat diet in MS patients before DMT were available. Modern day MS diet proponents may also observe subjective benefits of diet for MS patients, but research is difficult and expensive to conduct.

Since the holy grail of slowing MS progression is the reduction of MRI-assessed disease activity and accumulation of disability, researchers need to include those measurements in any study which aims to demonstrate that diet can fight MS progression. In a randomized controlled trial of a very low-fat, plant-based diet in MS that was recently published, researchers at the Oregon Health & Science University, in collaboration with the McDougall Research & Education Foundation, did just that.

The primary results of the pilot study (total subjects: 61, with 53 completing the study) are disappointing in that the very low-fat vegan diet — called the McDougall Diet — did not affect MS disease activity as measured by MRI (brain lesions and brain atrophy), number of relapses, or disability progression in patients with active relapsing-remitting MS and mild-to-moderate disability. However, the study did show significant reductions and improvement in MS-related fatigue, body weight, and cholesterol levels.

Participants in the trial were randomized into one of two groups: the diet group who attended a 10-day residential diet training program in Santa Rosa, California, to jump-start their new way of eating and who had on-going support from study staff and access to an online discussion board throughout the 12-month study; and the control group who ate their normal diet for 12 months, received an exercise education seminar at the beginning of the study, and were offered access to the residential program at the end of the study.

The study diet was based on starchy plant foods (beans, breads, corn, pastas, potatoes, sweet potatoes, and rice with the addition of fruits and non-starchy vegetables). Approximately 10 percent of calories were derived from fat,14 percent from protein, and 76 percent from carbohydrate. Meat, fish, eggs, dairy products and vegetable oils (such as corn and olive oil) were prohibited. During the diet training period, participants reported difficulty in limiting fat intake, but found that eliminating animal products was easier.

Most of the participants in both groups were on a DMT with 24/32 (75 percent) in the diet group and 20/29 (69 percent) in the control group using disease-modifying therapy. Fifteen participants (seven from the diet group and eight from the control group) experienced relapses during the study. Six participants in the diet group and two participants in the control group did not complete the study. However, a large majority (22/26; 85 percent) of the final diet group were able to stay on the diet consistently throughout the study.

Participants in the diet group lost weight primarily within in the first six months (about one-two pounds/month) which correlated with reductions in LDL cholesterol, total cholesterol, and fasting insulin levels. These changes would likely enhance long-term quality of life by reducing risk of cardiovascular disease in people with MS.

Researchers found a significant relationship between the diet intervention, weight loss, and reduced fatigue levels. After analyzing the results, researchers attribute 42.5 percent of the improvement of MS fatigue levels directly to weight loss. However, authors also suggested that improvement in fatigue may have resulted from increased socialization, participation in the dietary intervention, and the expectation of experiencing benefits from the diet. Future studies will need to include a control group that does not experience weight loss to better determine cause/effect relationships.

Bottom line: This study showed that eating a very low-fat, plant-based diet is feasible, safe, reduced BMI (body mass index), lipid and insulin levels, and appeared to improve fatigue. It remains uncertain whether this type of diet will positively change the course of MS. Larger and longer controlled studies are warranted.

See more helpful articles:

Can Diet Stop the Progression of MS?

MS Diet and Nutritional Approaches to Treatment

Diet That Mimics Fasting May Help Reduce MS Symptoms


Yadav V, Marracci G, et al. Low-fat, plant-based diet in multiple sclerosis: A randomized controlled trial. Mult Scler Rel Disord. 2016 Sep;9:80-90. http://dx.doi.org/10.1016/j.msard.2016.07.001

Oregon Oregon Health & Science University (2014). Low-fat diet helps fatigue in people with MS [press release]. Retrieved from http://www.ohsu.edu/xd/about/news_events/news/2014/05-01-low-fat-diet-helps-fatig.cfm