This study investigates the association between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and suicidal ideation in adults using data from the National Health and Nutrition Examination Survey (NHANES) in the United States from 2005 to 2016. The study found that higher NHHR levels were significantly and positively associated with an increased likelihood of suicidal ideation, even after adjusting for various confounding factors. The relationship between NHHR and suicidal ideation was described as an inverted U-shaped curve among nonsmokers, with an inflection point at 7.80. Subgroup analyses showed no significant interaction between NHHR and variables such as age, sex, race, BMI, education level, marital status, hypertension, diabetes, and smoking status. The study suggests that NHHR may serve as a predictive indicator of suicidal ideation, highlighting its potential utility in risk assessment and preventive strategies. The findings emphasize the potential link between lipid metabolism and mental health, prompting further research into preventive strategies and interventions. The study's strengths include the use of a nationally representative sample and comprehensive data analysis, while limitations include potential recall bias and the cross-sectional study design, which limits causal inference. Overall, the study contributes to the understanding of the relationship between lipid metabolism and suicidal ideation, suggesting that NHHR could be a valuable tool in assessing mental health risks.This study investigates the association between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and suicidal ideation in adults using data from the National Health and Nutrition Examination Survey (NHANES) in the United States from 2005 to 2016. The study found that higher NHHR levels were significantly and positively associated with an increased likelihood of suicidal ideation, even after adjusting for various confounding factors. The relationship between NHHR and suicidal ideation was described as an inverted U-shaped curve among nonsmokers, with an inflection point at 7.80. Subgroup analyses showed no significant interaction between NHHR and variables such as age, sex, race, BMI, education level, marital status, hypertension, diabetes, and smoking status. The study suggests that NHHR may serve as a predictive indicator of suicidal ideation, highlighting its potential utility in risk assessment and preventive strategies. The findings emphasize the potential link between lipid metabolism and mental health, prompting further research into preventive strategies and interventions. The study's strengths include the use of a nationally representative sample and comprehensive data analysis, while limitations include potential recall bias and the cross-sectional study design, which limits causal inference. Overall, the study contributes to the understanding of the relationship between lipid metabolism and suicidal ideation, suggesting that NHHR could be a valuable tool in assessing mental health risks.