Her presentation at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2020, held in Florida on Feb. 27–29, was titled “Caloric restriction and dietary interventions in MS.“
Diet, Obesity and MS
Mowry opened her talk with an overview of studies finding a link between healthier food choices and lower MS risk.
One that compared dietary patterns in adults with MS and healthy people in Australia (the Ausimmune Study) concluded that people who ate a Mediterranean diet — allowing for about one daily serving (65 g) of unprocessed red meat — were less likely to be diagnosed with MS. Eating more fish, particularly canned fish, also appeared to lower the chances of this disease.
Fish was seen as a good food choice in other work as well. A preliminary study of dietary habits in 1,153 people associated high consumption of fatty fish (one serving/week or 1–3 servings/month, plus daily fish oil supplements) with 45% lower odds of developing clinically isolated syndrome (CIS) or MS, compared to a diet poor in fish (less than once a month) and no fish oil supplements.
Omega-3 fatty acids, unsaturated fats abundant in seafood and flaxseed, could be responsible for this protective effect, although more data is needed.
Not all research supports healthier foods influencing MS risk. Data on more than 185,000 women participating in the Nurses‘ Health Study I and II found no meaningful link between diet quality and a person’s propensity for MS.
Results are also conflicting regarding salt or sodium intake. An Argentinian study found an association between a high-salt diet and worse clinical and radiological disease activity in relapsing-remitting MS (RRMS) patients. But a U.S. study in pediatric patients with CIS and RRMS, and data from the BENEFIT trial in CIS patients, found no such links.
Obesity as an MS risk factor is supported by several studies. In people with the disease, conditions related to obesity — like high levels of cholesterol and triglycerides, heart disease, or high blood pressure — appear to be linked with increases in brain lesions and inflammation.
A study by Mowry’s team, which followed 469 adults with CIS or RRMS for five years, suggests that obese patients lose gray matter volume (brain atrophy) more quickly over time. An excess in ‘bad’ fats (LDL cholesterol, triglycerides) that may promote inflammation, aggravating brain lesions, was given as a potential reason, but other mechanisms could also be involved.
Acknowledging a growing body of evidence, however, does not mean ignoring the potential pitfalls in many MS diet and risk studies. Patients may change their diets after being diagnosed, which can mislead results, and much of the work done looked at single points in time, instead of following outcomes over time (longitudinal studies).
Mowry is leading a long-term research project, called the CHARMS study (Characterizing Healthy Actions Relevant to MS), that aims to address these shortcomings. CHARMS, which is still recruiting people for its online surveys, will look into how lifestyle choices and habits, including diet, exercise habits, sleep schedules, or time spent outdoors, might influence MS progression.
Surveys arrive once every three months, and participants are asked to also contribute clinical records, like blood tests and MRI scans, for use (with safeguards) by Hopkins researchers in this study.
Responses collected to date seem to support a link between higher quality diets and better walking ability, cognitive function, and hand dexterity.
Studies into dietary approaches
Can any specific diet change disease course in MS?
Not anytime soon, in Mowry’s opinion, because no solid evidence exists.
She also noted considerable challenges in setting up and conducting relevant studies: Which type of diet and regimen should one choose? Can effectiveness best be measured by patient reports, or standard evaluations of biologic or neurologic outcomes? How can researchers ensure patients are following a diet as required?
Popular dietary plans, such as the Paleolithic (Wahls protocol), the gluten-free, and the Swank diet, provide very weak evidence of altering MS prognosis, Mowry said, noting much of the supporting evidence is “anecdotal” rather than “rigorous.”
A number of small pilot trials, however, are either underway or have results.
The modified diet studied consisted of eating fish and other foods high in poly- and mono-unsaturated fats (including omega-3 fatty acids), fresh fruits, vegetables, and whole grains. It eliminated meat, dairy, and most processed foods, and limited salt intake to less than 2 g/day.
This trial provided relevant information for future studies. Its researchers noted “high interest” and high adherence to the dietary plan, suggesting that patients are willing to participate in diet studies and improve their eating habits.
While patients tolerated and adhered to the diet well, no significant benefits were seen on brain MRI scans, relapse rates, or disability scores. People on this diet, however, reported a drop in fatigue levels and weight, and showed a better lipid (fat) profile, all of which could yield long-term health benefits, its researchers said.
Another single-site study put 20 relapsing MS patients on a modified Atkins diet, a type of ketogenic diet (a high-fat, low-carbohydrate diet that mimics fasting), for six months. Researchers found this diet to be safe and well-tolerated, and concluded it lessens fatigue and depression in patients, while promoting weight loss and reducing pro-inflammatory markers. Its lack of a non-diet patient group for comparison, however, weakens the value of its findings as evidence.
ATAC-MS fasting study
Preclinical evidence supports fasting, or caloric restriction, as beneficial to people with disorders that include MS. Disease severity and inflammation eased in MS mice models fed with 40% less food than normal (caloric restriction) or given a fasting-like diet.
Both diets were seen to protect the central nervous system (CNS) from nerve cell damage and demyelination (loss of the myelin coating on nerve fibers), a hallmark of MS. One that mimicked fasting also seemed to support myelin regeneration, or remyelination.
A pilot trial by Mowry’s group (NCT02647502), called the ATAC-MS Study (Altering the Timing or Amount of Calories in MS), compared two types of calorie-restricted diets against an unrestricted diet in 36 adults with RRMS.
Participants were randomized to one of three diets for eight weeks: a control diet (a normal, regular diet), a continuous calorie-restricted diet (a 22% reduction in calories each day), or an intermittent restricted diet (75% fewer calories for two days each week).
Weekly calorie intake was similar between the two restricted dietary plans. All meals were shipped directly to patients to ensure compliance. Thirty-one people finished the study: nine in the control group and 11 in each diet group.
Patients did fairly well, with those on a restricting diet losing weight (a median of 3.4 kg), showing a greater diversity in gut bacteria, and fewer symptoms of depression. Blood samples are now being studied for relevant changes in metabolism tied to a given diet.
Mowry also mentioned an ongoing intermittent fasting trial in RRMS patients (NCT03539094), which is now enrolling up to 60 people at its one site, the John L. Trotter MS Center at Washington University in St Louis.
“Likely diet is important for MS because of the direct effects, and indirectly through influencing obesity and the gut microbiota [the microorganisms residing in the gut],” Mowry said.
However, any one factor “likely does not exist in isolation — many lifestyle factors are intertwined and may have implications beyond MS,” she added.
While current evidence does not support any particular diet, people with MS — like those without this disease — should keep a healthy diet to promote overall good health and weight.
A number of MS specialists recommend that patients follow general guidelines given by the American Heart Association and the American Cancer Society: a diet low in fats and high in fiber, rounded off by regular exercise.
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