Age modifies the relationship between ultra-processed food intake and hyperuricemia: findings from NHANES 1999–2018

Hyperuricemia is a growing public health concern linked to gout, cardiovascular diseases, and metabolic syndrome. Ultra-processed foods (UPFs), characterized by industrial formulation with additives and minimal whole food content, have been hypothesized to be linked to uric acid overproduction through high levels of sugars, unhealthy fats, and purine precursors. This study aimed to investigate the association between UPF consumption and hyperuricemia across different age groups, hypothesizing that higher UPF intake is associated with higher odds of hyperuricemia, particularly in individuals under 60 years. Data from 43,713 adults aged ≥ 20 years from the National Health and Nutrition Examination Survey (NHANES) 1999–2018 were analyzed. Logistic regression models adjusted for sociodemographic, clinical, and lifestyle factors were used to assess the association between UPF ratio and hyperuricemia. Generalized additive models and stratified analyses were employed to evaluate non-linear relationships and potential interactions. In fully adjusted models, each unit increase in UPF ratio was associated with 31% higher odds of hyperuricemia in the total population (OR 1.31, 95% CI 1.15–1.48, P < 0.001). This association was strongest among middle-aged adults (45–59 years) (OR 1.49, 95% CI 1.15–1.92, P < 0.01), followed by young adults (< 45 years) (OR 1.35, 95% CI 1.10–1.66, P < 0.01), while no significant association was observed among older adults (≥ 60 years). Significant interactions modifying the UPF-hyperuricemia association were observed for race/ethnicity, drinking status, and diabetes in young adults, and for gender, race/ethnicity, and drinking status in older adults. UPF consumption is significantly associated with higher odds of hyperuricemia in adults under 60 years, with the strongest association observed in middle-aged adults. Age substantially modifies this relationship, with no significant association in adults aged ≥ 60 years. These findings suggest that age-specific dietary recommendations targeting UPF reduction may be relevant for hyperuricemia management, particularly in younger and middle-aged populations.