Association Between Dietary Anthocyanidin Intake and Thyroid Autoimmunity: A Cross-Sectional Study From NHANES...

Despite extensive documentation of the immunomodulatory effects of anthocyanidins, population-based epidemiological studies have yet to elucidate their association with thyroid autoimmunity (TAI).

Using flavonoid intake data from the Flavonoid and Anthocyanidin Database (FNDDS) and 2007-2010 National Health and Nutrition Examination Survey (NHANES) datasets (n = 5,487), we constructed multivariable logistic regression and restricted cubic spline models to examine the dose-response relationship between the log10-transformed anthocyanidin intake values (LgAAs) and TAI incidence, adjusting for demographic, anthropometric, and metabolic covariates.

The intake of anthocyanidins by TAI patients was significantly greater than that by controls [median (IQR): 2.20(0.00, 14.92) vs. 0.98 (0.00, 7.18) mg/d, p < 0.001]. Each unit increase in LgAA corresponded to a 16% increase in the risk of TAI (adjusted OR 1.16, 95% CI 1.04-1.29; p = 0.0088). Compared with the lowest quartile, the highest LgAA quartile was associated with a 47% increase in the incidence of TAI (OR 1.47, 95% CI 1.12-1.93; p = 0.0055; P trend = 0.014), with consistent associations across subgroups (P interaction = 0.528). Restricted cubic spline analysis confirmed a linear dose-response relationship (P nonlinearity = 0.217).

This cross-sectional study identified an association between dietary anthocyanidin intake and TAI. Future prospective cohort studies and randomized trials are warranted to validate our observations and elucidate underlying mechanisms.