Red blood cell folate and severe abdominal aortic calcification: results from the NHANES 2013-2014
Long Zhou Nutrition, Metabolism and Cardiovascular Diseases August 23, 2020
Highlights
• Red blood cell (RBC) folate concentration is a better indicator reflecting long-term folate intake than dietary or serum folate.
• Abdominal aortic calcification (AAC), a marker of subclinical atherosclerosis and CVD risk, has been introduced as a good predictor of CVD events.
• Both low (<400 ng/mL) and high (>800 ng/mL) levels of RBC folate were positively associated with increased odds for severe AAC, resulting in a U-shaped dose-response relationship.
• Both benefits and potential risks should be taken into consideration before deciding to increase folate consumption.
Background and aims
Abdominal aortic calcification (AAC) has been introduced as a good predictor of CVD events, but no previous study has investigated the relationship between folate levels and AAC. The present study aims to explore the relationship between red blood cell (RBC) folate, a better indicator reflecting long-term folate intake, and severe AAC in the United States (US) middle-aged and elderly population.
Methods and Results
Cross-sectional data were derived from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 of 2818 men and women aged 40 years or older. Multivariable logistic regression models were used to determine odds ratios (ORs) and 95% confidence intervals (CIs) for severe AAC of each RBC folate quintile category. The restricted cubic spline model was used for the dose-response analysis. A U-shaped dose-response relation between RBC folate and the odds of severe AAC was found after adjustment for multiple potential confounding factors, p for nonlinear =0.0032. With the third quintile category of RBC folate as the reference, multivariable-adjusted ORs and 95% CIs of the lowest, second, fourth, and the highest quintile categories were 2.34 (1.37-4.00), 1.24 (0.70-2.19), 1.58 (0.92-2.70), and 2.26 (1.35-3.76), respectively.
Conclusions
Individuals with either low or high levels of RBC folate were at increased risks of severe AAC in a representative sample of US adults. While folate deficiency is widely recognized as harmful, these results highlight the need to investigate the potential adverse health outcomes of high folate level.