Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disease primarily affecting individuals between the ages of 20 and 40. It is characterized by lesions in the central nervous system (CNS) which can lead to various cognitive and physical impairments, such as lack of coordination, paralysis, sensory disturbances, and visual impairments.
MS is classified into several subtypes based on different phenotypes, including clinically isolated syndrome, relapsing-remitting, primary progressive, and secondary progressive MS.
In England, there are eight to eleven new cases of MS per 100,000 individuals each year. Women are twice as likely to be diagnosed with MS compared to men.
MS is a multifactorial disease influenced by both genetic and environmental factors, including exposure to ultraviolet B (UVB) light, Epstein-Barr virus (EBV) infection, obesity, and smoking.
The Role of Diet in MS
Diet is a vital modulator of gut homeostasis and may influence CNS health through the gut-brain axis. Several studies have demonstrated that frequent consumption of food additives can lead to a “leaky gut” or gut dysbiosis, increasing the risk of Alzheimer’s disease (AD) and potentially MS.
A pro-inflammatory gut environment has been linked to an increased risk of MS. A recent United Kingdom Biobank cohort study found that a healthy lifestyle, including regular physical activity, maintaining a healthy body mass index (BMI), and following a healthy diet, is inversely associated with MS prevalence.
Consistent with these findings, another study observed that the intake of vegetables, fish, seafood, nuts, dairy, and whole grains positively impacts MS symptom improvement. Although several studies have reported the positive effects of a healthy diet on MS symptoms, the relationship between specific foods and MS risk remains unclear.
Study Overview
The current study utilized data 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 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 study employed 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, of which 70,467 participants met the eligibility criteria.
Over an average of twelve years of follow-up, 478 MS cases were identified within the study cohort, reflecting a prevalence rate of 7.78 MS events per 100,000 person-years.
Smoking as a Risk Factor
Smoking was identified as a modifiable risk factor that increases the risk of MS, with current smokers at greater risk compared to past smokers. Previous studies suggest that quitting smoking could reduce MS incidence by at least 13%.
Individuals who smoke, have vitamin D deficiency, a history of EBV infection, or carry the human leukocyte antigen (HLA) DR15*1501 gene are at increased risk of developing MS. Additionally, childhood and adolescent obesity, along with genetic determinants for obesity, were found to elevate the risk of MS. The cumulative effect of low-grade chronic inflammation, increased levels of leptin, decreased vitamin D bioavailability, and obesity can contribute to the development of MS.
The Protective Role of Fish Consumption
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, especially for individuals in regions with lower solar exposure that contributes to poor vitamin D synthesis.
A 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 preventive effects against AD and inflammatory diseases. Moreover, daily supplementation of four grams of fish oil has been shown to reduce the relapse rate and inflammation in MS patients.
The Impact of the Mediterranean Diet and Alcohol
Consistent with previous studies, the Mediterranean diet is associated with a reduction in non-communicable diseases. The current study also observed an inverse association between weekly alcohol consumption and MS risk. However, further research is needed to identify the types of alcohol that influence MS.
Conclusions
The study utilized data from the U.K. Biobank to evaluate the role of diet in the onset of MS. According to the FFQ data, moderate consumption of fatty fish and alcohol appears to reduce the risk of developing MS. Future research is needed to further explore the types of alcohol that influence MS and to clarify the complex relationship between diet and MS risk.
These findings underscore the importance of diet in modulating the risk of MS and suggest that lifestyle interventions, including dietary modifications, could play a crucial role in MS prevention and management.