Association Between Dietary Anthocyanidin Intake and Thyroid Autoimmunity: A Cross‐Sectional Study From NHANES (2007–2010)

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