Knowledge of Salt, Oil, and Sugar Reduction (“Three Reductions”) and Its Association with Nutrition-Related Chronic Diseases in Chinese Adults: A Nationwide Cross-Sectional Study

<b>Background/Objectives</b>: Excessive intake of salt, oil, and sugar constitutes a major dietary risk factor for chronic diseases in China. Although salt, oil, and sugar reduction ("Three Reductions") has been promoted at the national level, the population's knowledge remains inadequately evaluated. This study aimed to assess the "Three Reductions" knowledge level among Chinese adults and its association with nutrition-related chronic diseases. <b>Methods</b>: Data were obtained from the Chinese Nutrition and Health Knowledge Survey 2022, a nationally representative cross-sectional study. A total of 68,673 participants aged 18-64 years were recruited from 200 survey sites of 31 provinces by multi-stage stratified random cluster sampling methods. A standard questionnaire was used for data collection, and multivariable logistic regression models were employed to examine factors associated with "Three Reductions" knowledge and its relationship with chronic diseases. All analyses were weighted by complex sampling. <b>Results</b>: In 2022, the mean "Three Reductions" knowledge score was 16.43 ± 4.17 (the full score is 24 points), and the awareness rate was 49.3% (95% CI: 47.0-51.6%). Females, those with higher education and income levels, those employed in medical institutions, and residents in urban and eastern areas had higher "Three Reductions" levels (<i>p</i> < 0.05). The "Three Reductions" knowledge level was significantly associated with chronic disease risk (<i>p</i> < 0.05). Specifically, the risk of chronic disease was reduced by 5% in the medium-score group (OR = 0.95, 95% CI: 0.90-1.00) and by 11% in the high-score group (OR = 0.89, 95% CI: 0.84-0.95). <b>Conclusions</b>: "Three Reductions" knowledge among Chinese is at a moderate level, with a significant association between "Three Reductions" knowledge level and chronic disease status. Dissemination of "Three Reductions" knowledge, especially practical knowledge, should be enhanced at the national level through various routes to reduce chronic disease risk.