Increased antioxidant levels favour psoriasis risk reduction in specific populations: a cross-sectional study based on National Health and Nutrition Examination Survey (NHANES)

Oxidative stress is an important pathomechanism in psoriasis, and the oxidative balance score (OBS) serves as a standardised metric for assessing systemic oxidative status, but its association with psoriasis is unclear. This study included 18 023 adults from the National Health and Nutrition Examination Survey to investigate the relationship between OBS and psoriasis. After using a complex sampling weighting method, we performed multi-model logistic regression and stratified analysis with OBS as the exposure and psoriasis as the outcome for the primary analysis. Restricted cubic spline (RCS) plots were used to evaluate potential non-linear associations between OBS and psoriasis. In addition, we performed replication analyses using two 24-h dietary records data as a sensitivity test to ensure robustness of the results. Multi-model logistic regression analyses revealed no statistically meaningful link between OBS and psoriasis prevalence when accounting for all confounders (<i>P</i> > 0·05), but in stratified analyses, OBS demonstrated a significant association with reduced risk of psoriasis in individuals aged 60-80 years (OR = 0·27-0·35, <i>P</i> < 0·05). As part of the overall OBS, moderate dietary OBS demonstrated an association with reduced psoriasis risk in 60- to 80-year-olds (OR = 0·39-0·43, <i>P</i> < 0·05). Lifestyle OBS (LOBS) indicates a significant negative correlation with psoriasis risk among the 'Other Hispanic' group. (Q3 OR = 0·23, <i>P</i> < 0·05). The RCS showed a non-linear relationship between LOBS and psoriasis (non-linear <i>P</i> = 0·013). This study provides the first systematic confirmation of an association between OBS and a reduced risk of psoriasis in elderly populations and specific ethnic groups. These findings offer new insights and directions for the prevention and treatment of psoriasis.