So far, no cure has been developed for multiple sclerosis (MS), and available treatments focus on managing the symptoms.
Some suggest that specific dietary interventions could help with the management of MS, but as yet, there is insufficient research to lend full support to such claims.
Now, specialists from Washington University School of Medicine in St. Louis, MO, and the Jackson Laboratory for Genomic Medicine in Farmington, CT, are testing the effectiveness of one dietary approach in the management of this condition: intermittent fasting.
According to study co-author Dr. Laura Piccio, "People hear these miraculous stories about patients recovering the ability to walk after they started on this diet or that, and everyone wants to believe it."
But, she adds, "All we have right now are anecdotes. The fact is that diet may indeed help with MS symptoms, but the studies haven't been done."
After testing the effect of intermittent fasting on a mouse model of MS and obtaining promising results, Dr. Piccio and team conducted a pilot study on human patients to verify if the positive outcomes held strong.
The researchers' findings are now published in the journal Cell Metabolism.
Diet style may influence symptoms
Initially, Dr. Piccio and colleague Dr. Yanjiao Zhou conducted research on a mouse model of MS. In this study, some animals were on a limited fasting regimen, in which they were fed every other day for a period of 4 weeks.
Another set of mice was allowed to eat freely over the same period. All the mice then received a type of immunization meant to trigger symptoms consistent with MS.
Following these steps, all the rodents continued their respective diet regimens for an additional 7 weeks.
The researchers found that the mice placed on an intermittent fasting diet were more resilient to neurological damage and were less likely to develop symptoms such as muscle weakness, paralysis, and difficulty in moving.
Some of the rodents exposed to intermittent fasting did develop symptoms consistent with MS, however these were less critical than those seen in the mice that were fed plentifully on a daily basis.
Fasting and the immune response
Also, the fasting rodents appeared to be less exposed to inflammation, as they had lower levels of pro-inflammatory cells (T helper 17 cells), and instead they had higher levels of immunoregulatory cells (regulatory T cells).
"There are several possible ways fasting can affect inflammation and the immune response," says Dr. Picco. "One is by changing hormone levels."
"We found that levels of the anti-inflammatory hormone corticosterone were nearly twice as high in the fasting mice. But it also could act through the gut microbiome."
Dr. Laura Piccio
The researchers explain that the fasting mice also appeared to have more diverse gut microbiota, which has been linked to better health outcomes.
Thus, the rodents following the intermittent fasting regimen had higher levels of the Lactobacillus bacterium, a probiotic whose abundance in the gut has been linked to less severe MS symptoms.
Also, when the researchers tried transferring gut bacteria collected from the fasting mice to the guts of the non-fasting ones, they noticed that the latter became more resilient to MS-like symptoms.
This, the investigators say, suggests that certain gut bacteria may play a protective role.
Diet: 'An add-on to current treatments?'
Following these promising results in mice, Dr. Piccio and team started a pilot trial of 16 patients with MS. The participants were all asked to follow an intermittent energy restriction diet, which limited their calorie intake every other day for a period of 2 weeks.
At the end of the pilot trial, the team found similar changes in the participants' gut microbiota and immune systems to the ones previously observed in mice.
Now, Dr. Piccio and team are organizing a much larger study focusing on patients with relapsing-remitting MS, which is the most common form of this condition. It is characterized by bouts of symptoms with stable periods in-between.
This study will follow the participants over a 12-week period, during which half of the volunteers will continue to follow their usual Western-style diet without any alterations, whereas the other half will follow their usual diet for only 5 days each week and only consume 500 calories of vegetables for 2 days per week.
All the participants will continue to follow any injectable MS treatment already prescribed, and any patients experiencing a relapse during the study will receive the necessary treatment.
"We're not looking for clinical benefit, although we certainly hope to see an improvement," states Dr. Piccio.
"Because MS is so variable and people with relapsing-remitting MS can be stable and nearly symptom-free for long periods, you'd need a huge study to see any benefit," she explains.
"Instead," adds Dr. Piccio, "what we want to find out is whether people on limited fasts undergo changes to their metabolism, immune response, and microbiome similar to what we see in the mouse."
The researchers caution that such dietary changes — even if found effective — will not cure the disease, though they could make an important difference to MS patients' lives.
"I don't think any physician working with this disease thinks you can cure MS with diet alone," explains Dr. Piccio. "But we may be able to use it as an add-on to current treatments to help people feel better."