The association between flavonoid intake and first clinical diagnosis of central nervous system demyelination: a case-control study.

BACKGROUND

Dietary flavonoids, compounds found in foods like fruits, vegetables, and nuts, are prominent in the Mediterranean diet. Emerging evidence suggests flavonoids may influence multiple sclerosis (MS) pathology and risk, though observational studies are lacking.

OBJECTIVES

This study investigated associations between dietary flavonoid intake and risk of first clinical diagnosis of central nervous system demyelination (FCD).

METHODS

Analyses here utilise data from the Ausimmune Study, a multicenter case-control study (282 cases; 558 controls) matched on age, sex, and study region. Intakes of dietary flavonoids and subclasses thereof were estimated from food frequency questionnaire data. Conditional logistic regression models assessed associations between quartiles of flavonoid intake and FCD, adjusting for potential confounders. Mediation analysis evaluated whether food-derived flavonol and flavone intake mediated the relationship between Mediterranean diet adherence and FCD risk.

RESULTS

Higher total flavone intake was associated with reduced FCD risk in both unadjusted (OR: Q4vsQ1 = 0.55, 95 % CI 0.35-0.84, p-trend = 0.01) and adjusted models (aOR = 0.56, 95 % CI 0.34-0.91, p-trend = 0.01). When stratified by dietary source, significant inverse associations were observed for food-derived flavones and flavonols. Participants with the highest intake of food-derived flavones (aOR = 0.59, 95 % CI 0.36-0.97, p-trend = 0.02) and flavonol (aOR = 0.61, 95 % CI 0.38-1.00, p-trend = 0.02) had lower odds of FCD compared with the lowest quartile. Other subclasses and beverage-derived flavonoids were not significantly associated with FCD. Mediation analysis indicated that food-derived flavone and flavonol intake partially mediated the association between Mediterranean diet adherence and FCD risk (indirect effect aOR 0.89, 95 % CI 0.76-1.00), accounting for an estimated 28 per cent of the total effect.

CONCLUSION

Food-derived flavones and flavonols were inversely associated with FCD risk, and flavonoids may contribute to the potentially protective role of the Mediterranean diet in MS risk. Prospective studies are needed to investigate these dynamics further, including in MS progression.