Red blood cell folate and cardiovascular deaths among hypertensive adults, an 18-year follow-up of a national cohort

Association between RBC folate and diabetic nephropathy in Type2 diabetes mellitus patients: a cross-sectional study

Folates play a crucial role as cofactors in metabolic pathways, influencing biological methylation and nucleotide synthesis, which has a significant impact on overall health and disease susceptibility. Diabetic nephropathy (DN) is a prevalent and severe complication of diabetes mellitus (DM). The correlation between RBC folate and DN remains unclear currently. This study aims to assess whether RBC folate is associated with DN. Based on data from the NHANES (2011-2018), we conducted a cross-sectional study involving 3070 adults with type 2 DM (T2DM). Demographic factors, levels of folate and vitamin B12, dietary folate intakes, and relevant laboratory data were obtained from all participants. Logistic regression, fitting smooth curves, interaction effects were utilized to support the research objectives. Regression analyses demonstrated a positive relation between RBC folate and DN. (P < 0.001). A positive association between levels of RBC folate and the risk of DN was observed after full adjustment for all the confounding variables (odds ratio: 1.38, 95% confidence interval: 1.27-1.49, P < 0.001). Similar patterns of association were observed for subgroup analysis (all P values for interaction > 0.05). In addition, curve fitting after adjusting for all the confounding variables demonstrated that there was a linear relationship between RBC folate and DN (P for non-linearity = 0.147). Increased RBC folate levels were linked to a higher risk of DN in type 2 diabetes. RBC folate should be considered as a crucial indicator for folate status in DN.

High red blood cell folate is associated with an increased risk of diabetes death among a hypertensive cohort

The relationship between folate and diabetes remains inconclusive, possibly because of folate measured differentially between studies. Interference from mandatory folic acid fortification (FAF) has also been blamed. With both folate intake and circulating concentration measured, we assessed the relationship between folate and the risk of diabetes death in a hypertensive cohort established before FAF. We hypothesized that the association between folate and diabetes death is measurement dependent. We analyzed the data of 3133 hypertensive adults aged ≥19 years who participated in the Third National Health and Nutrition Examination Survey (1991-1994) and were followed up through December 31, 2010. Hazard ratios of diabetes death were estimated for participants with high (4th quarter) folate compared with those with moderate (2nd and 3rd quarters) or low (1st quarter) concentrations of folate. Dietary folate intake, total folate intake (including folate from supplements), serum, and red blood cell (RBC) folate were measured. After 42,025 person-years of follow-up, 165 diabetes deaths were recorded, and a dose-response positive association was observed between diabetes death and RBC folate. The adjusted hazard ratios of diabetes death were 1.00 (reference), 1.42 (95% CI. 1.20-1.68), and 2.21 (1.73-2.82), respectively, for hypertensive adults with low, moderate, and high RBC folate. No association was detected between diabetes death and serum folate concentration, folate intake, or either dietary intake or total intake. With minimized interference from FAF, neither dietary nor serum folate was associated with diabetes death, but elevated RBC folate was associated with a high risk of diabetes deaths among hypertensive patients.

Interactions of arsenic exposure, arsenic metabolism with red blood cell folate on the risk of hypertension: NHANES 2007-2016

PURPOSE

Arsenic exposure was associated with hypertension, and arsenic metabolism might be influenced by folate concentrations. Thus, this study aimed to explore the interaction between arsenic exposure and metabolism with folate concentrations on hypertension.

METHODS

We studied 6643 adults aged 20 years and older who participated in the National Health and Nutrition Examination Survey from 2007 through 2016. Urinary total arsenic (UTAs), the percentage of urinary dimethylarsinic acid (DMA%), serum and red blood cell (RBC) folate were collected. Logistic regression and restricted cubic spline (RCS) analyses were performed to determine the association and dose-response relationship. Interaction analyses were conducted on both additive and multiplicative scales.

RESULTS

UTAs (median: 7.05 μg/L) was positively associated with hypertension risk, and the adjusted OR was 1.44 (95% CI: 1.06-1.95) when comparing the third with the lowest quartile. And participants with the highest quintile of RBC folate had increased hypertension risk than those with the lowest quintile (adjusted OR = 1.43, 95% CI: 1.06-1.94). Significant additive interaction was observed between excessive RBC folate with high UTAs (AP = 0.323, 95% CI: 0.083-0.564) and low DMA% (AP = 0.381, 95% CI: 0.119-0.643) on hypertension risk.

CONCLUSION

Our results suggested significant interactions between high UTAs and low DMA% with excessive RBC folate on hypertension risk.

Non-linear associations of serum and red blood cell folate with risk of cardiovascular and all-cause mortality in hypertensive adults

This study aims to assess the associations of serum and red blood cell (RBC) folate with cardiovascular and all-cause mortality in hypertensive adults. Data on serum and RBC folate from the 1999-2014 National Health and Nutrition Examination Survey were included. Through December 31, 2015, cardiovascular and all-cause mortality were identified from the National Death Index. Multiple Cox regression and restricted cubic spline analyses were used to determine the relationship between folate concentrations and outcomes. A total of 13,986 hypertensive adults were included in the analysis (mean age, 58.5 ± 16.1 years; 6898 [49.3%] men). At a median of 7.0 years of follow-up, 548 cardiovascular deaths and 2726 all-cause deaths were identified. After multivariable adjustment, the fourth quartile of serum folate was associated with cardiovascular (HR = 1.32 [1.02-1.70]) and all-cause (HR = 1.20 [1.07-1.35]) mortality compared to the second quartile, whereas the first quartile was only linked with increased all-cause (HR = 1.29 [1.15-1.46]) mortality. The inflection points for the non-linear associations of serum folate with cardiovascular and all-cause mortality were 12.3 ng/mL and 20.5 ng/mL, respectively. In addition, the highest quartile of RBC folate was associated with cardiovascular (HR = 1.68 [1.30-2.16]) and all-cause (HR = 1.30 [1.16-1.46]) mortality compared to the second quartile, but the lowest quartile was not associated with either outcome. The inflection points for the non-linear associations of RBC folate with cardiovascular and all-cause mortality were 819.7 and 760.1 ng/mL, respectively. The findings suggest non-linear associations between serum and RBC folate levels and the risk of cardiovascular and all-cause mortality in hypertensive adults.

Associations of Serum Folate and Homocysteine Concentrations with All-Cause, Cardiovascular Disease, and Cancer Mortality in Men and Women in Korea: the Cardiovascular Disease Association Study

BACKGROUND

Evidence on the association of serum folate and homocysteine concentrations with risk of mortality in the general population is unclear.

OBJECTIVES

This study aimed to examine the associations of serum folate and homocysteine concentrations with all-cause, CVD, and cancer mortality risk in Korean men and women aged ≥40 y.

METHODS

In this population-based prospective cohort study, serum folate and homocysteine concentrations were measured in a subset of participants enrolled between 2005 and 2012. A total of 21,260 participants were linked to mortality data from the survey date to 31 December 2019. Cox proportional hazards models and restricted cubic splines were used to identify the associations of serum folate and homocysteine concentrations with mortality.

RESULTS

During a median follow-up of 12.3 y, 2501, 549, and 842 deaths were attributed to all-cause, CVD, and cancer, respectively. The prevalence of folate deficiency and hyperhomocysteinemia were higher in men than in women. In men, a nonlinear inverse association was observed between serum folate concentrations and all-cause mortality. Men in the third quartile of serum folate concentrations exhibited a lower risk of all-cause mortality (HR: 0.85; 95% CI: 0.73, 0.99) than those in the lowest quartile. Serum homocysteine concentration was positively associated with all-cause and CVD mortality. Men and women in the highest compared with those in the lowest serum homocysteine quartile showed a higher risk of CVD mortality (HR: 1.60; 95% CI: 1.07, 2.39; and HR: 1.79; 95% CI: 1.11, 2.89, respectively). Hyperhomocysteinemia combined with folate deficiency was associated with increased all-cause, CVD, and cancer-related mortality rates.

CONCLUSIONS

Higher serum homocysteine and lower serum folate concentrations were associated with an increased risk of all-cause, CVD, and cancer-related mortality in Korean adults. The finding of a nonlinear inverse relationship between serum folate concentration and mortality in men warrants further investigation.

Blood Lead Levels and Risk of Deaths from Cardiovascular Disease

Environmental exposure could be an important modifiable risk factor for cardiovascular disease (CVD). In this study, we investigated the relation between lead exposure, measured as blood lead levels (BLLs) and CVD mortality in a national cohort. A total of 15,036 adults aged ≥19 who participated in the National Health and Nutrition Examination Survey (1988 to 1994) as the baseline examination were followed up through December 31, 2010. Adjusted hazard ratios (HRs) derived from Cox proportional hazard regressions were used to estimate the risk of dying from CVD in association with BLLs. Cardiovascular mortality was 3.76, 8.11, and 14.77 per 1,000 person-years for patients in low, moderate, and high BLLs, respectively. After adjusting for potential confounders, patients in the high lead level had a significantly increased risk of death from all CVD (HR 1.35, 95% confidence interval 1.03 to 1.77), compared with those with low level. Participants in both moderate and high lead levels showed a significantly increased risk of death from heart disease, with an HR of 1.37 (1.04 to 1.81) and 1.60 (1.21 to 2.13), respectively. A significant linear association with all CVD and heart disease deaths was also seen with an HR of 1.08 (1.00 to 1.16) and 1.09 (1.02 to 1.16), respectively, per 1-unit increase in BLLs. In conclusion, the study demonstrates that increasing BLLs were associated with an increased risk of cardiovascular deaths, especially from heart disease. This further supports the possible cardiovascular effects that lead poses on patients at low levels of exposure and the importance of further reducing lead exposure in the general population.

Folate Status and Mortality in US Adults With Diabetes: A Nationally Representative Cohort Study

Background

Public health concerns have gradually shifted from inadequate intakes to potential adverse effects associated with excessive folate intakes following the full implementation of mandatory folate fortification. This study aimed to examine the associations of red blood cell (RBC) folate with all-cause and cardiovascular disease (CVD) mortality among patients with diabetes.

Methods

Data of 15,514 adults aged 20 years or older, who participated in the National Health and Nutrition Examination Survey (1988–1994), were analyzed as the baseline examination. The participants were linked to mortality data from the survey date until December 31, 2015. The associations of RBC folate with all-cause and CVD mortality were examined using multivariable Cox regression models.

Results

During 297,708 person–years of follow-up (median of 19.2 years), 6,106 total deaths occurred, including 1,867 deaths from CVD, 1452 deaths from ischemic heart disease, and 415 deaths from stroke disease. The participants with the highest quartile of RBC folate had higher odds of diabetes (fully-adjusted odds ratio: 1.94 [95% CI: 1.53–2.48]). In Cox regression analyses, compared with the participants with the lowest quartile of RBC folate for diabetes, those from quartile 3 and quartile 4 had HRs (95% CIs) of 1.12 (0.87, 1.43) and 1.30 (1.04, 1.63) in all-cause mortality, respectively; in CVD mortality, the HRs were 1.73 (1.08, 2.76) and 1.47 (0.98, 2.22); in ischemic heart disease mortality, they were 2.01 (1.19, 3.39) and 1.62 (1.05, 2.50), respectively. However, high levels of RBC folate were negatively associated with all-cause mortality, CVD mortality and ischemic heart disease mortality in non-diabetes.

Conclusion

From the nationally representative data, increasing levels in RBC folate were independently associated with an increased risk of all-cause and CVD mortality among those diagnosed with diabetes, but high levels of RBC folate had a mild protective effect in non-diabetes. The underlying mechanism regarding folate and adverse outcomes in diabetes warrants further clarification.

Associations of Serum and Red Blood Cell Folate With All-Cause and Cardiovascular Mortality Among Hypertensive Patients With Elevated Homocysteine

Objectives

This study aims to explore the associations between serum and red blood cell (RBC) folate as indicators of short- and long-term folate status, respectively, and all-cause as well as CVD mortality among hypertensive patients with elevated homocysteine.

Methods

A prospective cohort study of the National Health and Nutrition Examination Survey (1999–2006) and 2015 Linked Mortality File was performed. All-cause and CVD mortality risk estimated using Cox proportional hazards models with adjusting for multiple potential covariates.

Results

A total of 1,753 hypertensive patients with elevated homocysteine [mean (SD) age, 68.5 (13.1)] were included in the analysis. During a median follow-up of 10.0 years, a total of 899 all-cause and 257 CVD deaths occurred. Compared the highest with the lowest quartile of RBC folate, the multivariable adjusted hazard ratios and 95% confidence intervals for all-cause and CVD death were 1.13 (0.92–1.39) and 1.47 (1.01–2.16) respectively. There was a significant and positive trend between RBC folate and the risk of CVD death (p for trend = 0.0196). No significant association was found between serum folate and mortality risk among the study sample.

Conclusions

High level of RBC folate is associated with an increased risk of cardiovascular mortality among hypertensive patients with elevated homocysteine while serum folate has no such effects.