Does diet influence the onset of multiple sclerosis?

A recent Nutrients journal study determines whether diet influences the onset of multiple sclerosis (MS).

Study: The Role of Diet in Multiple Sclerosis Onset: A Prospective Study Using UK Biobank. Image Credit: Josep Suria / Shutterstock.com

What causes MS?

MS is a chronic autoimmune inflammatory disease that generally affects individuals between 20 and 40 years of age. MS is characterized by central nervous system (CNS) lesions that may cause cognitive or physical impairment, such as lack of coordination, paralysis, sensory disturbances, and visual impairments.

MS has been classified into many sub-types based on different phenotypes. These subtypes include clinically isolated syndrome, relapsing-remitting, primary progressive, and secondary progressive MS.

In England, eight to 11 new cases of MS out of every 100,000 individuals are reported each year. As compared to men, women are twice as likely to be diagnosed with MS.

MS is a multifactorial disease that can develop due to genetic and environmental factors such as exposure to ultraviolet B (UVB) light, Epstein-Barr virus (EBV) infection, obesity, and smoking.  

Diet is a vital modulator of gut homeostasis that may influence CNS health through the gut-brain axis. Several studies have shown that frequent consumption of food additives may lead to a “leaky gut” or gut dysbiosis that increases the risk of Alzheimer’s disease (AD).

A pro-inflammatory gut environment has also been reported to increase the risk of MS. To this end, a recent United Kingdom Biobank cohort study revealed a healthy lifestyle consisting of regular physical activity, healthy body mass index (BMI) values, and a healthy diet is inversely associated with MS prevalence.

Consistent with these findings, another study observed a positive impact of vegetable, fish, seafood, nuts, dairy, and whole grain intake with MS symptom improvement. Although several studies have reported the positive effects of a healthy diet on MS symptoms, the relationship between single foods and MS risk remains unclear.

About the study

The current study utilized data obtained from the U.K. Biobank cohort to explore the association between diet and MS onset. The U.K. Biobank is one of the largest publicly available healthcare resources used to identify the genetic, environmental, and lifestyle factors for various health conditions.

At baseline, study participants completed a food frequency questionnaire (FFQ) that provided relevant information about their diet. National Health Service (NHS) records from England, Scottish Morbidity Records, and the Patient Episode Database for Wales were used to assess MS diagnoses and outcomes.

Study findings

The current study utilized a prospective and multi-faceted approach to elucidate the role of diet in MS onset. Data from 502,507 individuals between the ages of 40 and 69 were available from the U.K. Biobank, 70,467 of whom were selected for the study based on the eligibility criteria.

An average of twelve years of long-term follow-up data were available, during which 478 MS cases from the study cohort were identified. This reflected a prevalence rate of 7.78 MS events for every 100,000 person-years.

Smoking was identified as a modifiable risk factor that increases the risk of MS, with current smokers, not past smokers, found to be at a greater risk of developing MS. Notably, previous studies have predicted that quitting smoking could reduce MS incidence by at least 13%.

Individuals who smoke, have vitamin D deficiency, a history of EBV infection, or human leukocyte antigen (HLA) DR15*1501 are at an increased MS risk. In addition to smoking, both childhood and adolescent obesity, as well as genetic determinants for obesity, were found to increase the risk of MS. A cumulative effect of low-grade chronic inflammation, increased levels of leptin, decreased vitamin D bioavailability, and obesity can contribute to the development of MS.

Moderate fish consumption, particularly eating oily fish once a week, was associated with a slightly better protective effect against MS incidence than more frequent intake. Fatty fish intake during adolescence or later in life is inversely associated with MS risk, with these benefits particularly applicable for individuals residing in areas with lower solar exposure that contributes to poor vitamin D synthesis.

One previous study indicated that fatty fish, a good source of omega-3 polyunsaturated fatty acids (PUFAs), mediate the immunomodulatory functions of vitamin D. PUFAs have been found to have a preventive effect against AD and inflammatory diseases. Moreover, four grams of fish oil supplementation daily has also been shown to reduce the relapse rate and inflammation in MS patients.

Consistent with previous studies, the Mediterranean diet positively prevents non-communicable diseases. An inverse association between weekly alcohol consumption and MS risk was also observed.

Conclusions

The current study used the U.K. Biobank database to evaluate the role of diet on MS onset. Based on the FFQ data, moderate fatty fish and alcohol consumption reduced the risk of MS development. In the future, additional research is needed to identify the types of alcohol that influence MS.