Higher urinary nitrate was associated with lower prevalence of congestive heart failure: results from NHANES.BACKGROUND
 Some studies have reported that nitrate intake from vegetables was inversely associated with many vascular diseases, but few studies have paid attention to the relationship between urinary nitrate and cardiovascular diseases (CVDs).  This cross-sectional study aimed to explore the connections between urinary nitrate and prevalence of CVDs.


 The data of this study was collected from National Health and Nutrition Examination Survey (NHANES).  Finally, several years' data of NHANES were merged into 14,894 observations.  Logistic regression models were used to examine the associations between urinary nitrate and CVDs by using the "survey" package in R software (version 3.2.3).


 RESULTS
 In the univariable logistic analysis, significant association was discovered between urinary nitrate and congestive heart failure, coronary heart disease, angina pectoris, myocardial infarction (all P < 0.001).  By adjusting related covariates, the multivariable logistic analysis showed that the significant association only existed between urinary nitrate and congestive heart failure (OR = 0.651, 95% CI 0.507-0.838, P < 0.001).  Compared to Q1 urinary nitrate level as reference, the risk for prevalent heart failure diminished along with increasing levels of urinary nitrates, (OR of Q2 level = 0.633, 95% CI 0.403-0.994), (OR of Q3 level = 0.425, 95% CI 0.230-0.783), (OR of Q4 level = 0.375, 95% CI 0.210-0.661), respectively.  Moreover, urinary nitrate levels were associated with congestive heart failure in a dose-dependent manner in both 20-60 years group, 60+ years group and male, female group (P < 0.001, P = 0.011 and P = 0.009, P = 0.004).


 Independent of related covariates, higher urinary nitrate was associated with lower prevalent congestive heart failure.
R
Logistic regression models were used to examine the associations between urinary nitrate and CVDs by using the "survey" package in R software (version 3.2.3).



R software (version 3.2.3)