Impact of Dietary Niacin on Metabolic Dysfunction-Associated Steatotic Liver Disease in Mediterranean Subjects: A Population-Based Study.

Background: The impact of dietary niacin on metabolic dysfunction-associated steatotic liver disease (MASLD) is elusive. This sub-study aimed to investigate the relationship between dietary niacin intake and the presence of MASLD in participants from two Catalonian cohorts.

Methods: A total of 222 subjects with MASLD were age- and sex-matched to 222 non-MASLD subjects. Dietary nutrients were analyzed using a validated food frequency questionnaire (FFQ). Dietary niacin and other nutrients were adjusted for total energy intake. MASLD was defined by a Fatty Liver Index (FLI) of >60 and by having at least one component of metabolic syndrome. The association between niacin intake (distributed into tertiles) and the presence of MASLD was assessed using multivariate logistic regression. Potential non-linear relationships were also analyzed through restricted cubic spline regression (RCS).

Results: Our data revealed that subjects with MASLD had worse metabolic profiles. The dietary intake of niacin did not differ between subjects with and without MASLD. Even after adjusting for different confounding variables, i.e., sociodemographic variables, smoking status, physical activity, and cardiometabolic comorbidities, no significant associations were observed between higher intakes of niacin (tertiles 2 and 3) and the presence of MASLD: odds ratio (95% confidence) second tertile: 0.99 (0.89-1.09); third tertile: 0.98 (0.89-1.10). However, RCS analysis uncovered a significant non-linear dose-response association between dietary niacin intake and odds of MASLD. Specifically, such analysis revealed that MASLD risk was decreased in subjects with niacin intake values of <35 mg/day.

Conclusions: Our data showed that dietary niacin intake was associated with lower odds of MASLD in a Mediterranean population; however, our logistic regression analysis failed to reveal significant associations between the intake of niacin and the risk of MASLD. Further research is warranted to establish a causal relationship between dietary niacin interventions and MASLD.