The L-shaped link between total antioxidant capacity and phenotypic age acceleration: evidence from NHANES 2003–2010

This study aimed to investigate the relationship between total antioxidant capacity (TAC) and phenotypic age acceleration (PhenoAgeAccel), a measure of accelerated biological aging, using data from the National Health and Nutrition Examination Survey (NHANES). Data from the 2003-2010 NHANES surveys, encompassing 16,395 participants, were analyzed. Principal component analysis (PCA) was used to reduce data dimensionality. Multivariate logistic regression models were employed to evaluate the association between TAC and antioxidant vitamins (α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein-zeaxanthin, vitamin A, vitamin C, vitamin E) with PhenoAgeAccel, adjusting for demographic, lifestyle, and clinical factors. Smoothed curve fitting and threshold effects analysis were conducted to explore the nonlinear relationship between log-transformed TAC and PhenoAgeAccel. Subgroup analyses were performed to assess potential effect modifiers based on age, gender, race, education, smoking, alcohol use, diabetes, hypertension, and hyperlipidemia. The weak correlations between the original variables prevent PCA from effectively capturing the primary variability within the data. Higher TAC was significantly inversely associated with PhenoAgeAccel in both unadjusted and adjusted models. Participants in the second tertile (T2) of TAC exhibited 11% lower odds of PhenoAgeAccel compared to those in the first tertile (T1) (OR = 0.89, 95% CI: 0.81-0.98, P = 0.0176). Intake of several antioxidant vitamins, including α-carotene, β-carotene, lutein-zeaxanthin, vitamin A, vitamin C, and vitamin E, was also inversely associated with the odds of PhenoAgeAccel. A nonlinear relationship between log-transformed TAC and PhenoAgeAccel was observed, with a significant protective effect within a specific range of TAC. Subgroup analyses revealed no significant effect modification by most factors, except for gender, smoking, and alcohol consumption. TAC is closely associated with PhenoAgeAccel. A nonlinear relationship was observed, with higher TAC exhibiting significant protective effects within a specific range, particularly among males, smokers, and alcohol consumer. These findings underscore the potential value of TAC in mitigating the aging process.