Ultra-processed food consumption and multiple sclerosis incidence: A prospective cohort study

Emerging evidence suggests an association between ultra-processed food (UPF) consumption and neurodegenerative diseases, but there is limited evidence for multiple sclerosis (MS). Diets rich in UPFs promote inflammation and oxidative stress that both play an important role in modulating the immune system, and thereby, potentially the pathogenesis of MS. This study aimed to investigate the longitudinal association between UPF consumption and MS onset in middle-aged and older adults.

The study included 185,788 adults who completed at least one valid dietary assessment and did not have MS at baseline (2009-2012). Dietary data was collected at 5 time points using a web-based 24-h dietary recall, and UPFs were categorised using the Nova food classification system. MS cases were identified based on medical history and linkage to data on hospital admissions (using ICD-coded diagnoses ICD10-g35; ICD9-3409), and self-reported MS diagnosis. Prospective associations between UPF consumption (as a percentage of total food intake in grams per day) and risk of MS onset were assessed using multivariable Cox proportional hazards models were adjusted for age, sex, ethnicity, education, Townsend deprivation index, smoking status, total energy intake and serum 25-hydroxyvitamin D.

Participants had a mean age of 56.0 years (SD 8.0) and 54% were female. UPFs comprised 19.1% of total dietary grams intake, with carbonated drinks, ready-to- eat/heat meals and industrial-processed breads being the most consumed UPF subgroups. Over a mean follow-up of 8.9 years (SD: 2.7), 384 incident MS cases occurred. Each 10% increase in UPF consumption was associated with an estimated 9% increase in risk of MS (HR 1.09; 95% CI: 1.003 to 1.19; p-value = 0.04).

This study found a weak yet significant association between higher UPF consumption and increased risk of MS in middle-aged and older adults. Given the modest effect size and inconsistency of statistical significance across sensitivity analyses, these findings should be interpreted with caution. Research to confirm these findings in other population groups and contexts is needed.