B-vitamins, methylenetetrahydrofolate reductase (MTHFR) and hypertension

Association of MTHFR Polymorphisms with H-Type Hypertension: A Systemic Review and Network Meta-Analysis of Diagnostic Test Accuracy

Purpose

An association between MTHFR polymorphisms and H-type hypertension (H-HTN) has been investigated by epidemiological studies, but results have been inconsistent. Thus, a systematic assessment of the association was performed based on a literature review and pooled analysis, to provide stronger evidence on the effects of single nucleotide polymorphisms on H-HTN risk.

Methods

Three investigators independently retrieved relevant studies in PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), Wanfang Database, and China Biomedical Literature Database (CBM). A fixed or random effects model was selected to calculate pooled odds ratio (OR) and 95% confidence intervals (CIs). A network meta-analysis of diagnostic test and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false-positive report probability (FPRP) for noteworthy associations. All data were processed using Stata 15.0 and Meta-Disc.

Results

A total of 14 studies involving 1759 cases and 1581 controls for MTHFR were included in our meta-analysis. In a direct meta-analysis, we found that MTHFR C667T rs1801133 significantly increased the risk of H-HTN susceptibility except for an overdominant model. However, MTHFR A1298C rs1801131 polymorphism had no significant correlation with H-HTN risk. Besides, MTHFR C667T rs1801133 is a potential diagnostic biomarker for estimating H-HTN risk. The results indicated that the dominant model was an optimal diagnosis model for excluding diseases, which could reduce a missed diagnosis rate and further improve the accuracy of disease diagnosis.

Conclusion

The present result suggests that MTHFR C667T rs1801133 polymorphism is associated with H-HTN risk and may act as a promising predictive biomarker for H-HTN risk. However, further well-designed studies are warranted to confirm these results.

Proteomics and metabolomics of raw rhubarb and wine-processed rhubarb in the treatment of rats with intracerebral hemorrhage

Background

To explore the mechanisms of raw rhubarb and wine-processed rhubarb treatment in a rat model of intracerebral hemorrhage (ICH).

Methods

After adapting to their environment, 30 male Wistar rats were divided into 5 treatment groups: blank control group (CK) (normal saline), sham operation group (SICH) (normal saline), ICH model group (ICH) (normal saline), ICH + raw rhubarb enema group (RO) (raw rhubarb 3.60 g/kg), and ICH + wine-processed rhubarb enema group (WRO) (wine-processed rhubarb 3.60 g/kg). The rhubarb enema (once a day) was given since 3 days before ICH treatment, and was consistently given until 12 hours, 24 hours, 3 days, and 7 days post operation. Serum oxidative stress and inflammatory markers were detected by ELISA, and differences between raw rhubarb and wine-processed rhubarb treatment in ICH rats were screened by proteomics and metabolomics.

Results

Both rhubarb treatments effectively improved oxidative stress and inflammatory responses. After ICH, the proteins and metabolites in the brain tissue were significantly altered. Compared with raw rhubarb, wine-processed rhubarb had a better protective effect by dysregulating amino acid metabolism in the ICH model.

Conclusions

Our study provides a basis for further research into the mechanisms of rhubarb treatment from different processing technologies, and promotes the application of rhubarb as a therapeutic approach to ICH.

Personalised nutrition - phenotypic and genetic variation in response to dietary intervention

Personalised nutrition allows individual differences in dietary, lifestyle, anthropometry, phenotype and/or genomic profile to be used to direct specific dietary advice. For personalised nutrition advice to be effective both sides need to be considered; firstly, that factors influencing variation in response to dietary intervention are identified and appropriate advice can be derived and secondly; that these are then used effectively in the provision of nutrition advice, resulting in a positive dietary and/or lifestyle behaviour change. There is considerable evidence demonstrating genetic and phenotypic influence on the biological response to the consumption of nutrients and bioactives. However, findings are often mixed, with studies often investigating at the level of a single nutrient/bioactive and/or a single genetic/phenotypic variation, meaning the derivation of specific advice at a dietary level in an individual/group of individuals can be complex. Similarly, the impact of using this information to derive personalised advice is also mixed, with some studies demonstrating no effectiveness and others showing a significant impact. The present paper will outline examples of phenotypic and genetic variation influencing response to nutritional interventions, and will consider how they could be used in the provision of personalised nutrition.

Association of MTHFR C677T gene polymorphism with metabolic syndrome in a Chinese population: a case-control study

Objective

To investigate the association of the MTHFR C677T gene polymorphism with metabolic syndrome (MetS) in people in Hubei Province, China.

Methods

A case–control study was conducted with 651 subjects with MetS (MetS group) and 727 healthy controls (control group) at Renmin Hospital of Wuhan University between January and December 2016. The MTHFR C677T genotype was detected by the gene chip technique and clinical data were collected.

Results

Body mass index, waist circumference, the waist-hip-ratio, systolic and diastolic blood pressure, fasting blood glucose, fasting insulin, triglyceride, total cholesterol, low-density lipoprotein-cholesterol, and homocysteine levels, and the homeostasis model assessment of insulin resistance were higher in the MetS group than in controls. The risk of MetS was higher for the TT genotype and T allele carriers than for the CC genotype and C allele carriers. With MetS, the TT genotype increased the risk of elevated blood pressure, fasting glucose levels, and triglyceride levels. Patients with MetS and the TT genotype showed more severe abdominal obesity, dyslipidaemia, insulin resistance, elevated blood pressure, elevated fasting glucose levels, and hyperhomocysteinaemia compared with those with the CC genotype.

Conclusions

In this population, MTHFR C677T gene polymorphism may be a risk factor for MetS.

Proposed guidelines to evaluate scientific validity and evidence for genotype-based dietary advice

Nutrigenetic research examines the effects of inter-individual differences in genotype on responses to nutrients and other food components, in the context of health and of nutrient requirements. A practical application of nutrigenetics is the use of personal genetic information to guide recommendations for dietary choices that are more efficacious at the individual or genetic subgroup level relative to generic dietary advice. Nutrigenetics is unregulated, with no defined standards, beyond some commercially adopted codes of practice. Only a few official nutrition-related professional bodies have embraced the subject, and, consequently, there is a lack of educational resources or guidance for implementation of the outcomes of nutrigenetic research. To avoid misuse and to protect the public, personalised nutrigenetic advice and information should be based on clear evidence of validity grounded in a careful and defensible interpretation of outcomes from nutrigenetic research studies. Evidence requirements are clearly stated and assessed within the context of state-of-the-art 'evidence-based nutrition'. We have developed and present here a draft framework that can be used to assess the strength of the evidence for scientific validity of nutrigenetic knowledge and whether 'actionable'. In addition, we propose that this framework be used as the basis for developing transparent and scientifically sound advice to the public based on nutrigenetic tests. We feel that although this area is still in its infancy, minimal guidelines are required. Though these guidelines are based on semi-quantitative data, they should stimulate debate on their utility. This framework will be revised biennially, as knowledge on the subject increases.

Biomarkers of Nutrition for Development-Folate Review

The Biomarkers of Nutrition for Development (BOND) project is designed to provide evidence-based advice to anyone with an interest in the role of nutrition in health. Specifically, the BOND program provides state-of-the-art information and service with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect. To accomplish this objective, expert panels are recruited to evaluate the literature and to draft comprehensive reports on the current state of the art with regard to specific nutrient biology and available biomarkers for assessing nutrients in body tissues at the individual and population level. Phase I of the BOND project includes the evaluation of biomarkers for 6 nutrients: iodine, iron, zinc, folate, vitamin A, and vitamin B-12. This review represents the second in the series of reviews and covers all relevant aspects of folate biology and biomarkers. The article is organized to provide the reader with a full appreciation of folate's history as a public health issue, its biology, and an overview of available biomarkers (serum folate, RBC folate, and plasma homocysteine concentrations) and their interpretation across a range of clinical and population-based uses. The article also includes a list of priority research needs for advancing the area of folate biomarkers related to nutritional health status and development.

Hypertension and the fat-soluble vitamins A, D and E

Hypertension affects populations globally and is thus a public health and socio-economic problem. Macronutrient and micronutrient deficiencies are common in the general population, and may be even more prevalent in hypertensive patients. This study aimed to determine a possible association between hypertension and intake of fat-soluble vitamins A, D and E. Participants were from the cross-sectional Hortega nutrition study conducted with a random sample of 1514 people (50.3% women, 49.7% men) and two groups: nonhypertensive controls ≥40 years old (n = 429; 28.3%); unknown untreated hypertension cases ≥40 years old (n = 246; 16.2%). Biochemical and anthropometric measurements were taken. Data on dietary intakes, education, socio-economic status, place of residence, health habits, comorbidities, alcohol consumption and smoking were collected and assessed. A descriptive data study was done and compared by ANOVA and Chi-Square. No p value higher than 0.05 was considered significant. The results showed that vitamin A intake was higher in the hypertensive subpopulation (1732.77 ± 962.27 µg vs. 1655.89 ± 902.81 µg), and vitamin D and E intakes were lower (8.13 ± 9.71 µg vs. 8.25 ± 9.52 µg and 18.79 ± 7.84 mg vs. 18.60 ± 8.20 mg, respectively). No statistically significant differences were found in any adjusted model. This study did not significantly associate intake of vitamins A, D and E with hypertension in people aged over 40. Future studies on this topic and a larger sample are necessary.

Dietary contributors to hypertension in adults reviewed

Recent national surveys which measured respondents' blood pressure (BP) levels have shown a high prevalence of hypertension amongst the Irish population, with approximately two-thirds of men and over half of women aged 45 years and over affected. Higher prevalence rates are observed with advancing age. Established diet- and lifestyle-related risk factors for hypertension such as high salt intake, high alcohol consumption and physical inactivity are pervasive in Ireland and are believed to contribute significantly to the high national prevalence of this condition. Additional dietary deficits have been implicated in the development of hypertension, however, including low fruit and vegetable intake, low dairy food consumption and low intake of oily fish. Deficiencies of single micro-nutrients such as folate, riboflavin, vitamin C and vitamin D have also been recently recognised as risk factors for hypertension. For each of these factors, there is evidence that the food and nutrient intakes of many Irish adults fall short of the ideal. These dietary and nutritional deficits, when superimposed on Ireland's existing health-subversive behaviours and escalating rates of obesity, constitute a potent constellation of risk factors for hypertension. However, they also represent viable and potentially effective targets for health promotion initiatives. This review aims to describe the main nutritional, dietary and lifestyle contributors to hypertension in Ireland with a view to informing future interventions aimed at alleviating Ireland's burden of hypertensive disease.

Concept mapping One-Carbon Metabolism to model future ontologies for nutrient-gene-phenotype interactions

Advances in the development of bioinformatic tools continue to improve investigators' ability to interrogate, organize, and derive knowledge from large amounts of heterogeneous information. These tools often require advanced technical skills not possessed by life scientists. User-friendly, low-barrier-to-entry methods of visualizing nutrigenomics information are yet to be developed. We utilized concept mapping software from the Institute for Human and Machine Cognition to create a conceptual model of diet and health-related data that provides a foundation for future nutrigenomics ontologies describing published nutrient-gene/polymorphism-phenotype data. In this model, maps containing phenotype, nutrient, gene product, and genetic polymorphism interactions are visualized as triples of two concepts linked together by a linking phrase. These triples, or "knowledge propositions," contextualize aggregated data and information into easy-to-read knowledge maps. Maps of these triples enable visualization of genes spanning the One-Carbon Metabolism (OCM) pathway, their sequence variants, and multiple literature-mined associations including concepts relevant to nutrition, phenotypes, and health. The concept map development process documents the incongruity of information derived from pathway databases versus literature resources. This conceptual model highlights the importance of incorporating information about genes in upstream pathways that provide substrates, as well as downstream pathways that utilize products of the pathway under investigation, in this case OCM. Other genes and their polymorphisms, such as TCN2 and FUT2, although not directly involved in OCM, potentially alter OCM pathway functionality. These upstream gene products regulate substrates such as B12. Constellations of polymorphisms affecting the functionality of genes along OCM, together with substrate and cofactor availability, may impact resultant phenotypes. These conceptual maps provide a foundational framework for development of nutrient-gene/polymorphism-phenotype ontologies and systems visualization.

Nutrigenetics and personalized nutrition: are we ready for DNA-based dietary advice?

Common genetic variation affects individual nutrient requirements and the use of DNA-based dietary advice, derived from nutrigenetics, has been growing. The growth is about to accelerate as the cost of genotyping continues to fall and research results from major nutrigenetics projects are published. There is still some skepticism; some barriers remain including some commercial tests, which make exaggerated, incorrect claims. There is a need for more public resources dedicated to unbiased, objective review and dissemination of nutrigenetics information; however, nutrigenetics evidence should be assessed in the context of standard nutritional evidence and should not require higher standards. This article argues that we are ready for some DNA-based dietary advice in general nutrition and it can be beneficial. Examples of the scientific validity and health utility of gene-diet interactions will be given and the development of guidelines for assessment and validation of benefits will be discussed.

Vitamins and iron blood biomarkers are associated with blood pressure levels in European adolescents. The HELENA study

OBJECTIVES

Previous research showed that low concentration of biomarkers in the blood during adolescence (i.e., iron status; retinol; and vitamins B6, B12, C, and D) may be involved in the early stages of development of many chronic diseases, such as hypertension. The aim was to evaluate if iron biomarkers and vitamins in the blood are associated with blood pressure in European adolescents.

METHODS

Participants from the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study (N = 1089; 12.5-17.5 y; 580 girls) were selected by complex sampling. Multilevel linear regression models examined the associations between iron biomarkers and vitamins in the blood and blood pressure; the analyses were stratified by sex and adjusted for contextual and individual potential confounders.

RESULTS

A positive association was found in girls between RBC folate concentration and systolic blood pressure (SBP) (β = 3.19; 95% confidence interval [CI], 0.61-5.77), although no association between the vitamin serum biomarkers concentrations and diastolic blood pressure (DBP) was found. In boys, retinol was positively associated with DBP (β = 3.84; 95% CI, 0.51-7.17) and vitamin B6 was positively associated with SBP (β = 3.82; 95% CI, 1.46-6.18). In contrast, holotranscobalamin was inversely associated with SBP (β = -3.74; 95% CI, -7.28 to -0.21).

CONCLUSIONS

Levels of RBC folate and vitamin B6 in blood may affect BP in adolescents. In this context, programs aimed at avoiding high BP levels should promote healthy eating behavior by focusing on the promotion of vegetable proteins and foods rich in vitamin B12 (i.e., white meat and eggs), which may help to achieve BP blood control in adolescents.

A nutrient-wide association study on blood pressure

BACKGROUND

A nutrient-wide approach may be useful to comprehensively test and validate associations between nutrients (derived from foods and supplements) and blood pressure (BP) in an unbiased manner.

METHODS AND RESULTS

Data from 4680 participants aged 40 to 59 years in the cross-sectional International Study of Macro/Micronutrients and Blood Pressure (INTERMAP) were stratified randomly into training and testing sets. US National Health and Nutrition Examination Survey (NHANES) four cross-sectional cohorts (1999-2000, 2001-2002, 2003-2004, 2005-2006) were used for external validation. We performed multiple linear regression analyses associating each of 82 nutrients and 3 urine electrolytes with systolic and diastolic BP in the INTERMAP training set. Significant findings were validated in the INTERMAP testing set and further in the NHANES cohorts (false discovery rate <5% in training, P<0.05 for internal and external validation). Among the validated nutrients, alcohol and urinary sodium-to-potassium ratio were directly associated with systolic BP, and dietary phosphorus, magnesium, iron, thiamin, folacin, and riboflavin were inversely associated with systolic BP. In addition, dietary folacin and riboflavin were inversely associated with diastolic BP. The absolute effect sizes in the validation data (NHANES) ranged from 0.97 mm Hg lower systolic BP (phosphorus) to 0.39 mm Hg lower systolic BP (thiamin) per 1-SD difference in nutrient variable. Inclusion of nutrient intake from supplements in addition to foods gave similar results for some nutrients, though it attenuated the associations of folacin, thiamin, and riboflavin intake with BP.

CONCLUSIONS

We identified significant inverse associations between B vitamins and BP, relationships hitherto poorly investigated. Our analyses represent a systematic unbiased approach to the evaluation and validation of nutrient-BP associations.

Importance of riboflavin kinase in the pathogenesis of stroke

AIMS

To explore risk factors for stroke independent of hypertension and the relationship between riboflavin kinase (RFK) and stroke.

METHODS

Gene expression profiling in the brains of spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) was comparatively analyzed by gene chips. The differentially expressed gene RFK was further verified by q-PCR and Western blot. The protective role of RFK-regulated flavins (including riboflavin, flavin mononucleotide, and flavin adenine dinucleotide) in stroke was observed in middle cerebral artery occlusion (MCAO) mice. Influence of flavins on apoptosis and death in oxygen and glucose deprivation (OGD)-treated neurons was examined by flow cytometry. Bax and Bcl-2 proteins were detected by Western blot.

RESULTS

Of the 76 differentially expressed genes, 41 genes were upregulated, and 35 genes were downregulated in SHRSP as compared with SHR. RFK was significantly downregulated in SHRSP. Flavins markedly decreased infarct area in MCAO mice, inhibited apoptosis and death in OGD-treated neurons, and decreased Bax protein expression.

CONCLUSIONS

Physiological downregulation of RFK may be a new potential risk factor for stroke, which probably affects the absorbance and utility of riboflavin and further destroys the protective effect of flavins on stroke. RFK might act as a therapeutic target for stroke.