Serum Vitamin C concentrations are inversely related to biological aging: a population-based cross-sectional study.

Background and objective: Vitamin C (Vit C), which has antioxidant properties, may reduce oxidative stress and delay aging. However, the relationship between Vit C and biological aging is poorly established. Therefore, we aimed to investigate the association between serum Vit C (S-vit C) concentrations and phenotypic age acceleration (PhenoAgeAccel), an indicator of biological aging.

Methods: The present study utilized a cross-sectional design using NHANES-retrieved data from 10,118 participants aged 20-79. Weighted linear regression models alongside restricted cubic spline analysis were deployed to determine the association. A two-piecewise linear regression model and a log-likelihood ratio test were utilized to assess the potential threshold effect. Using the subgroup analyses, we explored variations in association across different subgroups while utilizing the sensitivity analyses to validate the strength of the outcomes.

Results: S-vit C concentrations were inversely related to PhenoAgeAccel. Participants in the highest quartile of S-vit C levels showed significantly reduced PhenoAgeAccel compared to those in the lowest quartile. A nonlinear relationship was identified between S-vit C levels and PhenoAgeAccel, characterized by an inflection point at 1.46 mg/dL. Beyond this threshold, further increases in S-vit C concentrations did not result in statistically significant reductions in PhenoAgeAccel. The results of subgroup analyses showcased that the inverse association was more substantial among older adults and individuals with hypertension or diabetes. The sensitivity analyses validated the strength of the outcomes.

Conclusions: S-vit C levels exhibit an inverse association with biological aging, particularly in older individuals and those with chronic conditions, highlighting the potential role of Vit C in healthy aging.