Dietary glycine and blood pressure: the International Study on Macro/Micronutrients and Blood Pressure

Dietary amino acid profile and risk of hypertension: findings from the Ravansar cohort study

INTRODUCTION

Hypertension (HTN) is a significant global health concern associated with morbidity and mortality. Recent research has explored the potential relationship between dietary protein intake and the development of HTN. This study aims to investigate the association between dietary amino acids and the incidence of HTN.

METHODS

This nested case-control study utilized data from the Ravansar Non-Communicable Disease (RaNCD) Cohort Study. The study included 491 new HTN cases identified over a 6-year follow-up period. For each case, four controls were randomly selected through density sampling. A food frequency questionnaire (FFQ) consisting of 125 food items was used to calculate dietary amino acid intake. HTN was determined based on systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg and/or current use of antihypertensive medication in subjects without pre-existing HTN at the start of the cohort study. Conditional logistic regression was used to estimate crude and adjusted odds ratios for HTN risk.

RESULTS

The median intake of all amino acids was lower in patients with HTN compared to the control group. After adjusting for various variables in different models, the risk of developing HTN tended to increase with higher dietary amino acid intake (excluding tryptophan and acidic amino acids). Specifically, individuals in the third tertile had a higher risk of developing new HTN than those individuals in the lowest tertile, although this difference was not statistically significant (P > 0.05).

CONCLUSION

The findings suggest that there may be an association between increased dietary amino acid intake and the risk of developing HTN, although this association was not statistically significant in this study. Further investigations in diverse populations are needed to explore the relationship between amino acids and HTN, as well as to determine the potential positive and negative effects of specific amino acid patterns on hypertension.

Dietary branched-chain amino acids intake and new-onset hypertension: a nationwide prospective cohort study in China

OBJECTIVE

This study aimed to investigate the relationship between dietary branched-chain amino acids (BCAAs) and the risk of developing hypertension.

METHODS

A cohort study of 14,883 Chinese adults without hypertension at baseline with were followed for an average of 8.9 years. Dietary intakes of BCAAs, including Ile, Leu, and Val, were collected using 3-day 24-h meal recall and household condiment weighing. Cox proportional hazards regression, restricted cubic splines, interaction analysis, and sensitivity analysis were used to assess the relationship between dietary BCAAs and risk of developing self-reported hypertension, adjusting for age, gender, region, body mass index (BMI), smoking and drinking status, physical activity, energy intake, salt intake.

RESULTS

Among 14,883 study subjects, 6386(42.9%) subjects aged ≥ 45 years at baseline, 2692 (18.1%) had new-onset hypertension during the study period, with a median age of 56 years. High levels of dietary BCAAs were associated with an increased risk of new-onset hypertension. Compared with the 41st-60th percentile, multivariable adjusted hazard ratio (HR) for new-onset hypertension was 1.16 (95% CI 1.01-1.32) for dietary BCAAs 61st-80th percentiles, 1.30 (1.13-1.50) for 81st-95th, 1.60 (1.32-1.95) for 96th-100th. The cut-off value of new-onset hypertension risk, total BCAAs, Ile, Leu, and Val were 15.7 g/day, 4.1 g/day, 6.9 g/day, 4.6 g/day, respectively, and the proportion of the population above these intake values were 13.9%, 13.1%, 15.4%, and 14.4%, respectively. Age, BMI, and salt intake had an interactive effect on this relationship (P < 0.001).

CONCLUSION

There was a significant positive association between total dietary BCAAs, Ile, Leu, Val intake and the risk of developing hypertension, after adjustment for confounders. This relationship was influenced by age, BMI, and salt intake. Further research is needed to clarify the mechanism and potential role of BCAAs in the pathogenesis of hypertension.

Genetic Insights into Glycine's Protective Role Against CAD - European and East Asia, 2015 and 2020

Introduction

The purpose of this study is to examine the potential causal relationship between levels of circulating glycine and coronary artery disease (CAD) using a two-step Mendelian randomization (MR) analysis.

Methods

We analyzed data from genome-wide association studies (GWAS) conducted on European and East Asian populations. To assess the causal effects of circulating glycine levels on the risk of CAD. We used the inverse-variance weighting (IVW), weighted median (WM), MR-Egger, and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) methods. Furthermore, we conducted mediation analysis to investigate the contribution of blood pressure and other cardiovascular disease-related traits.

Results

The two-step Mendelian randomization analysis revealed that higher levels of glycine in the blood were associated with a reduced risk of CAD in Europeans [odds ratio ( OR)=0.84, 95% confidence interval ( CI): 0.72, -0.98; P=0.029] and East Asians: ( OR=0.76, 95% CI: 0.66, -0.89; P=3.57×10 -4). Sensitivity analysis confirmed the robustness of these findings. Additionally, our results suggest that about 6.06% of the observed causal effect is mediated through genetically predicted systolic blood pressure (SBP) in the European population.

Discussion

Our results contribute to the current knowledge regarding the involvement of glycine in the progression of CAD, and provide valuable methodological insights for the prevention and treatment of this condition.

Dietary amino acids and risk of stroke subtypes: a prospective analysis of 356,000 participants in seven European countries

PURPOSE

Previously reported associations of protein-rich foods with stroke subtypes have prompted interest in the assessment of individual amino acids. We examined the associations of dietary amino acids with risks of ischaemic and haemorrhagic stroke in the EPIC study.

METHODS

We analysed data from 356,142 participants from seven European countries. Dietary intakes of 19 individual amino acids were assessed using validated country-specific dietary questionnaires, calibrated using additional 24-h dietary recalls. Multivariable-adjusted Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of ischaemic and haemorrhagic stroke in relation to the intake of each amino acid. The role of blood pressure as a potential mechanism was assessed in 267,642 (75%) participants.

RESULTS

After a median follow-up of 12.9 years, 4295 participants had an ischaemic stroke and 1375 participants had a haemorrhagic stroke. After correction for multiple testing, a higher intake of proline (as a percent of total protein) was associated with a 12% lower risk of ischaemic stroke (HR per 1 SD higher intake 0.88; 95% CI 0.82, 0.94). The association persisted after mutual adjustment for all other amino acids, systolic and diastolic blood pressure. The inverse associations of isoleucine, leucine, valine, phenylalanine, threonine, tryptophan, glutamic acid, serine and tyrosine with ischaemic stroke were each attenuated with adjustment for proline intake. For haemorrhagic stroke, no statistically significant associations were observed in the continuous analyses after correcting for multiple testing.

CONCLUSION

Higher proline intake may be associated with a lower risk of ischaemic stroke, independent of other dietary amino acids and blood pressure.

The Associations of Genetically Predicted Plasma Alanine with Coronary Artery Disease and its Risk Factors: A Mendelian Randomization Study

BACKGROUND

Alanine is an amino acid commonly used as a nutritional supplement and plays a key role in the glucose-alanine cycle. Plasma alanine has been associated in observational studies with a higher risk of coronary artery disease (CAD) and unhealthier lipid profiles. However, evidence from large randomized controlled trials is lacking.

OBJECTIVES

Using Mendelian randomization (MR), we assessed the unconfounded associations of plasma alanine with CAD and CAD risk factors.

METHODS

We applied single nucleotide polymorphisms that were strongly (P < 5 ×10-8) associated with plasma alanine as genetic instruments to large genome-wide association studies of CAD (63,108 cases; 296,901 controls), diabetes (90,612 cases; 583,493 controls), glucose (515,538 participants), lipids (low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, triglycerides, total cholesterol, and apolipoprotein B) (>1.1 million participants), blood pressure (BP) (757,601 participants), and body mass index (682,137 participants). Given the potential sex disparity, we also conducted sex-specific analyses. MR estimates per standard deviation increase in alanine concentrations were obtained using inverse variance weighting followed by sensitivity analyses using weighted median, MR-Egger, MR-Pleiotropy RESidual Sum and Outlier, and MR-Robust Adjusted Profile Score.

RESULTS

Genetically predicted plasma alanine was not associated with CAD but with a higher risk of diabetes (odds ratio [OR]: 1.35; 95% confidence interval [CI]: 1.06, 1.72), higher glucose (β: 0.11; 95% CI: 0.02, 0.19), LDL cholesterol (β: 0.08; 95% CI: 0.04, 0.12), triglycerides (β: 0.25; 95% CI: 0.13, 0.38), total cholesterol (β: 0.14; 95% CI: 0.08, 0.20), apolipoprotein B (β: 0.12; 95% CI: 0.03, 0.21), and BP (β: 1.17; 95% CI: 0.31, 2.04 for systolic BP: β: 0.97; 95% CI: 0.49, 1.45 for diastolic BP) overall. The positive associations of serum alanine with LDL cholesterol and triglycerides were more notable in women than in men.

CONCLUSIONS

Alanine or factors affecting alanine may have causal effects on diabetes, blood glucose, lipid profiles, and BP but not on CAD. Further studies are needed to clarify possible mechanisms.

Targeting metabolism in aortic aneurysm and dissection: from basic research to clinical applications

Aortic aneurysm and dissection (AAD) are a group of insidious and lethal cardiovascular diseases that characterized by seriously threatening the life and health of people, but lack effective nonsurgical interventions. Alterations in metabolites are increasingly recognized as universal features of AAD because metabolic abnormalities have been identified not only in arterial tissue but also in blood and vascular cells from both patients and animal models with this disease. Over the past few decades, studies have further supported this notion by linking AAD to various types of metabolites such as those derived from gut microbiota or involved in TCA cycle or lipid metabolism. Many of these altered metabolites may contribute to the pathogenesis of AAD. This review aims to illustrate the close association between body metabolism and the occurrence and development of AAD, as well as summarize the significance of metabolites correlated with the pathological process of AAD. This provides valuable insight for developing new therapeutic agents for AAD. Therefore, we present a brief overview of metabolism in AAD biology, including signaling pathways involved in these processes and current clinical studies targeting AAD metabolisms. It is necessary to understand the metabolic mechanisms underlying AAD to provides significant knowledge for AAD diagnosis and new therapeutics for treatment.

Dietary amino acids and anthropometric indices: Tehran Lipid and Glucose Study

Objective

Recent studies investigated the role of amino acids (AAs) in weight management. We aimed to determine the association between AAs and three-year change of anthropometric indices and incident obesity.

Materials and methods

Height, weight, hip, and waist circumference (WC) were collected at baseline and follow up. Three-year changes in anthropometric indices and obesity incident according to body mass index (BMI) (overweight & obesity) and WC cutoffs (obesity-WC) were ascertained. Dietary intakes of AAs were collected at baseline, using a food frequency questionnaire. Data analyses were conducted on 4976 adult participants and two subsamples, including 1,570 and 2,918 subjects, for assessing the AAs relationship with 3-year changes on anthropometric indices and obesity incident.

Results

Lysine and aspartic acid were positively associated with higher weight change, whereas acidic AAs, cysteine, and glutamic acid showed a negative correlation with weight change. Furthermore, a weak positive correlation was shown for alkaline AAs, lysine, and valine with WC; however, acidic AAs, tryptophan, cysteine, and glutamic acid were negatively associated with WC. Aromatic and acidic AAs also demonstrated a weak negative relation with changes in BAI. Phenylalanine and Aromatic AAs showed a negative association with overweight &obesity incidence adjusting for potential confounders. Each quartile increases the dietary lysine, arginine, alanine, methionine, aspartic acid, and alkaline AAs related to a greater risk of obesity-WC, while tryptophan, glutamic acid, proline, and acidic AAs associated with lower obesity-WC risk.

Conclusion

Our results suggested that certain dietary AAs may potentially change anthropometric indices and risk of obesity incident.

Habitual Tea Consumption Increases the Incidence of Metabolic Syndrome in Middle-Aged and Older Individuals

In middle-aged and elderly individuals, the relationship between tea consumption and incident metabolic syndrome (MetS) is still unclear. Therefore, this study intends to figure out the relationship between tea-drinking frequency and MetS in rural middle-aged and older Chinese residents. In the Northeast China Rural Cardiovascular Health Study, 3632 middle-aged or older individuals (mean age 57 ± 8, 55.2% men) without MetS were included at baseline during 2012–2013 and were followed up on between 2015–2017. Participants showing differential tea consumption frequency were divided into the following classes: non-habitual tea drinkers, occasional tea drinkers, 1–2 times/day drinkers, and ≥3 times/day drinkers. Data showed that non-habitual tea drinking was more common among women. The frequency of tea consumption was higher in ethnic groups other than Han and among singles, as well as in concurrent smokers and drinkers and individuals with primary or lower educational status. The increasing tea consumption was in line with baseline elevations in body mass index, systolic and diastolic blood pressure, high-density lipoprotein cholesterol (HDL-C), and AST/ALT ratio. Multivariate logistic regression analysis confirmed that occasional tea drinking increased the incidence of low HDL-C [OR (95% CI): 1.268 (1.015, 1.584)], high waist circumference [OR (95% CI): 1.336 (1.102, 1.621)], and MetS [OR (95% CI): 1.284 (1.050, 1.570)]. In addition, 1–2 times/day tea drinking increased the cumulative incidence of high TG [OR (95% CI): 1.296 (1.040, 1.616)], high waist circumference [OR (95% CI): 1.296 (1.044, 1.609)] and MetS [OR (95% CI): 1.376 (1.030, 1.760)]. We demonstrated that regular tea consumption is correlated with a greater incidence of metabolic disorders and MetS. Our findings may help clarify the contradictory association reported between tea drinking and MetS development in middle-aged and older residents of rural China.

Effects of glycine on metabolic syndrome components: a review

PURPOSE

Glycine is the simplest and major amino acid in humans. It is mainly generated in the liver and kidney and is used to produce collagen, creatine, glucose and purine. It is also involved in immune function, anti-inflammatory processes and anti-oxidation reactions. Here, we reviewed the current evidence supporting the role of glycine in the development and treatment of metabolic syndrome components.

METHODS

We searched Scopus, PubMed and EMBASE databases for papers concerning glycine and metabolic syndrome.

RESULTS

Available evidence shows that the amount of glycine synthesized in vivo is insufficient to meet metabolic demands in these species. Plasma glycine levels are lower in subjects with metabolic syndrome than in healthy individuals. Interventions such as lifestyle modification, exercise, weight loss, or drugs that improve manifestations of metabolic syndrome remarkably increase circulating glycine concentrations.

CONCLUSION

Glycine supplementation improves various components of metabolic syndrome including diabetes, obesity, hyperlipidemia and hypertension. In the future, the use of glycine may have a significant clinical impact on the treatment of patients with metabolic syndrome.

Blood pressure and urine metabolite changes in spontaneously hypertensive rats treated with leaf extract of Ficus deltoidea var angustifolia

Ficus deltoidea var angustifolia (FD-A) reduces blood pressure in spontaneously hypertensive rats (SHR) but the mechanism remains unknown. Changes in urine metabolites following FD-A treatment in SHR were, therefore, examined to identify the mechanism of its antihypertensive action. Male SHR were given either FD-A (1000 mg kg^-1 day^-1) or losartan (10 mg kg^-1 day^-1) or 0.5 mL of ethanolic-water (control) daily for 4 weeks. Systolic blood pressure (SBP) was measured every week and urine spectra data acquisition, on urine collected after four weeks of treatment, were compared using multivariate data analysis. SBP in FD-A and losartan treated rats was significantly lower than that in the controls after four weeks of treatment. Urine spectra analysis revealed 24 potential biomarkers with variable importance projections (VIP) above 0.5. These included creatine, hippurate, benzoate, trimethylamine N-oxide, taurine, dimethylamine, homocysteine, allantoin, methylamine, n-phenylacetylglycine, guanidinoacetate, creatinine, lactate, glucarate, kynurenine, ethanolamine, betaine, 3-hydroxybutyrate, glycine, lysine, glutamine, 2-hydroxyphenylacetate, 3-indoxylsulfate and sarcosine. From the profile of these metabolites, it seems that FD-A affects urinary levels of metabolites like taurine, hypotaurine, glycine, serine, threonine, alanine, aspartate and glutamine. Alterations in these and the pathways involved in their metabolism might underlie the molecular mechanism of its antihypertensive action.

Association between Protein Intake and Skeletal Muscle Mass among Community-Dwelling Older Japanese: Results from the DOSANCO Health Study: A Cross-Sectional Study

Whether the source of dietary protein intake is related to appendicular skeletal muscle mass (AMM) and muscle mass (MM) remains unclear. We conducted this cross-sectional study of 277 residents (115 men, 162 women) aged ≥65 years in Japan to examine the association of the amount of dietary protein intake with AMM and MM. We measured dietary protein intake using a brief self-administered diet history questionnaire. AMM and MM were assessed based on bioelectrical impedance. Multivariable linear regression analyses were used to estimate β coefficients that were adjusted for potential confounders. Among Japanese women aged ≥75 years, but not among women aged 65-74 years, dietary animal protein intake was significantly associated with AMM (β (95% confidence interval (CI)): 0.25 (0.10, 0.40)) and MM (β (95% CI): 0.40 (0.16, 0.64)). However, dietary vegetable protein intake was not associated with AMM (β (95% CI): -0.17 (-0.74, 0.41)) and MM (β (95% CI): -0.30 (-1.23, 0.63)). Furthermore, in men aged ≥65 years, dietary protein intake was not associated with AMM or MM. In conclusion, dietary animal protein intake, but not vegetable protein intake, were positively associated with AMM and MM among this population of Japanese women aged ≥75 years.

Association Between Blood Pressure and Branched-Chain/Aromatic Amino Acid Excretion Rate in 24-Hour Urine Samples from Elderly Hypertension Patients

BACKGROUND

Recently, the association between lifestyle-related diseases and free amino acids in the blood plasma-especially branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs)-has been highlighted. However, few studies have been carried out on 24-hour urine samples. Therefore, we aimed to explore the relationships between 24-hour urinary BCAAs and AAAs excretion rate and blood pressure (BP) in elderly patients with hypertension.

METHODS AND RESULTS

Each of the 322 elderly patients with hypertension completed an in-person questionnaire interview, underwent a physical examination, and provided a 24-hour urine specimen. We measured their BCAAs and AAAs excretion rate, and used multiple linear regression analysis with variable selection to construct models describing the relationships between their BCAAs and AAAs excretion rate and BP. After adjusted for age, gender, height, and weight, valine was inversely associated with both systolic blood pressure (SBP) (β: -0.232, 95% CI: -0.16, -0.006) and diastolic blood pressure (DBP) (β: -0.144, 95% CI: -0.089, -0.005). These findings were invariant even following adjustment for urine volume and drugs history, and Ile was positively associated with DBP (β: 0.170, 95% CI: 0.001, 0.066).

CONCLUSION

The data revealed that the excretion rate of 24-hour urinary BCAAs was closely related to BP in elderly hypertension patients, and these findings will provide new insights into the association between BACC metabolism and BP.

Amino Acids and Developmental Origins of Hypertension

During pregnancy, amino acids are important biomolecules that play essential roles in fetal growth and development. Imbalanced amino acid intake during gestation may produce long-term morphological or functional changes in offspring, for example, developmental programming that increases the risk of developing hypertension in later life. Conversely, supplementation with specific amino acids could reverse the programming processes in early life, which may counteract the rising epidemic of hypertension. This review provides an overview of the evidence supporting the importance of amino acids during pregnancy and fetal development, the impact of amino acids on blood pressure regulation, insight from animal models in which amino acids were used to prevent hypertension of developmental origin, and interactions between amino acids and the common mechanisms underlying development programming of hypertension. A better understanding of the pathophysiological roles of specific amino acids and their interactions in developmental programming of hypertension is essential so that pregnant mothers are able to benefit from accurate amino acid supplementation during pregnancy in order to prevent hypertension development in their children.

Metabolites and Hypertension: Insights into Hypertension as a Metabolic Disorder: 2019 Harriet Dustan Award

For over 100 years, essential hypertension has been researched from different perspectives ranging from genetics, physiology, and immunology to more recent ones encompassing microbiology (microbiota) as a previously underappreciated field of study contributing to the cause of hypertension. Each field of study in isolation has uniquely contributed to a variety of underlying mechanisms of blood pressure regulation. Even so, clinical management of essential hypertension has remained somewhat static. We, therefore, asked if there are any converging lines of evidence from these individual fields that could be amenable for a better clinical prognosis. Accordingly, here we present converging evidence which support the view that metabolic dysfunction underlies essential hypertension.

Human urine 1H NMR metabolomics reveals alterations of protein and carbohydrate metabolism when comparing habitual Average Danish diet vs. healthy New Nordic diet

OBJECTIVES

The aim of this study was to investigate the alteration of the human urine metabolome by means of diet and to compare the metabolic effects of the nutritionally healthy New Nordic Diet (NND) with an Average Danish Diet (ADD). The NND was designed a decade ago by scientists and chefs, based on local and sustainable foods, including fish, shellfish, vegetables, roots, fruit, and berries. The NND has been proven to lower blood pressure, reduce glycemia, and lead to weight loss.

METHODS

The human urine metabolome was measured by untargeted proton nuclear magnetic resonance spectroscopy in samples from 142 centrally obese Danes (20-66 years old), randomized to consume the ADD or the NND. The resulting metabolomics data was processed and analyzed using advanced multivariate data analysis methods to reveal effects related to the design factors, including diet, season, sex, and changes in body weight.

RESULTS

Exploration of the nuclear magnetic resonance profiles revealed unique metabolite markers reflecting changes in protein and carbohydrate metabolism between the two diets. Glycine betaine, glucose, trimethylamine N-oxide and creatinine were increased in urine of the individuals following the NND compared with the ADD population, whereas relative concentrations of tartrate, dimethyl sulfone, and propylene glycol were decreased. Propylene glycol had a strong association with the homeostatic model assessment for insulin resistance in the NND group. The food intake biomarkers found in this study confirm the importance of these as tools for nutritional research.

CONCLUSIONS

Findings from this study provided new insights into the effects of a healthy diet on glycemia, reduction of inflammation, and weight loss among obese individuals, and alteration of the gut microbiota metabolism.

BOLA (BolA Family Member 3) Deficiency Controls Endothelial Metabolism and Glycine Homeostasis in Pulmonary Hypertension

BACKGROUND

Deficiencies of iron-sulfur (Fe-S) clusters, metal complexes that control redox state and mitochondrial metabolism, have been linked to pulmonary hypertension (PH), a deadly vascular disease with poorly defined molecular origins. BOLA3 (BolA Family Member 3) regulates Fe-S biogenesis, and mutations in BOLA3 result in multiple mitochondrial dysfunction syndrome, a fatal disorder associated with PH. The mechanistic role of BOLA3 in PH remains undefined.

METHODS

In vitro assessment of BOLA3 regulation and gain- and loss-of-function assays were performed in human pulmonary artery endothelial cells using siRNA and lentiviral vectors expressing the mitochondrial isoform of BOLA3. Polymeric nanoparticle 7C1 was used for lung endothelium-specific delivery of BOLA3 siRNA oligonucleotides in mice. Overexpression of pulmonary vascular BOLA3 was performed by orotracheal transgene delivery of adeno-associated virus in mouse models of PH.

RESULTS

In cultured hypoxic pulmonary artery endothelial cells, lung from human patients with Group 1 and 3 PH, and multiple rodent models of PH, endothelial BOLA3 expression was downregulated, which involved hypoxia inducible factor-2α-dependent transcriptional repression via histone deacetylase 1-mediated histone deacetylation. In vitro gain- and loss-of-function studies demonstrated that BOLA3 regulated Fe-S integrity, thus modulating lipoate-containing 2-oxoacid dehydrogenases with consequent control over glycolysis and mitochondrial respiration. In contexts of siRNA knockdown and naturally occurring human genetic mutation, cellular BOLA3 deficiency downregulated the glycine cleavage system protein H, thus bolstering intracellular glycine content. In the setting of these alterations of oxidative metabolism and glycine levels, BOLA3 deficiency increased endothelial proliferation, survival, and vasoconstriction while decreasing angiogenic potential. In vivo, pharmacological knockdown of endothelial BOLA3 and targeted overexpression of BOLA3 in mice demonstrated that BOLA3 deficiency promotes histological and hemodynamic manifestations of PH. Notably, the therapeutic effects of BOLA3 expression were reversed by exogenous glycine supplementation.

CONCLUSIONS

BOLA3 acts as a crucial lynchpin connecting Fe-S-dependent oxidative respiration and glycine homeostasis with endothelial metabolic reprogramming critical to PH pathogenesis. These results provide a molecular explanation for the clinical associations linking PH with hyperglycinemic syndromes and mitochondrial disorders. These findings also identify novel metabolic targets, including those involved in epigenetics, Fe-S biogenesis, and glycine biology, for diagnostic and therapeutic development.

Various proline food sources and blood pressure: substitution analysis

The aim of this study was to investigate the association of total proline intake, proline of various food sources, and substitution analysis for proline of food sources with blood pressure (BP) and 3.1-year incidence of hypertension in the framework of the Tehran Lipid and Glucose Study. The cohort consisted of 4287 participants (41.9% male), aged ≥ 20-70 years. In fully-adjusted model, individuals in the highest tertile for proline intake had an increased risk of incident hypertension than those in the lowest one (OR: 1.45; 95%CI: 1.06-1.97; p for trend: .017). Replacing proline of cheese and legumes source with that of yogurt, poultry, milk, and red meat source was associated with significant negative β coefficient for BP. The present study indicated that high dietary intakes of proline may increase the risk of incident hypertension. Also, substituting proline intake of cheese and legumes by those of proline intake of meats and milk is associated with a lower risk of high BP.

Amino Acids and Hypertension in Adults

Accumulating evidence suggests a potential role of dietary protein among nutritional factors interfering with the regulation of blood pressure. Dietary protein source (plant versus animal protein), and especially, protein composition in terms of amino acids has been postulated to interfere with mechanisms underlying the development of hypertension. Recently, mounting interest has been directed at amino acids in hypertension focusing on habitual dietary intake and their circulating levels regardless of single amino acid dietary supplementation. The aim of the present review was to summarize epidemiological evidence concerning the connection between amino acids and hypertension. Due to the large variability in methodologies used for assessing amino acid levels and heterogeneity in the results obtained, it was not possible to draw robust conclusions. Indeed, some classes of amino acids or individual amino acids showed non-causative association with blood pressure as well as the incidence of hypertension, but the evidence was far from being conclusive. Further research should be prompted for a thorough understanding of amino acid effects and synergistic actions of different amino acid classes on blood pressure regulation.

Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: the Adventist Health Study-2 cohort

Background

Current evidence suggests that plant and animal proteins are intimately associated with specific large nutrient clusters that may explain part of their complex relation with cardiovascular health. We aimed at evaluating the association between specific patterns of protein intake with cardiovascular mortality.

Methods

We selected 81 337 men and women from the Adventist Health Study-2. Diet was assessed between 2002 and 2007, by using a validated food frequency questionnaire. Dietary patterns based on the participants' protein consumption were derived by factor analysis. Cox regression analysis was used to estimate multivariate-adjusted hazard ratios (HRs) adjusted for sociodemographic and lifestyle factors and dietary components.

Results

There were 2276 cardiovascular deaths during a mean follow-up time of 9.4 years. The HRs for cardiovascular mortality were 1.61 [98.75% confidence interval (CI), 1.12 2.32; P-trend < 0.001] for the 'Meat' protein factor and 0.60 (98.75% CI, 0.42 0.86; P-trend < 0.001) for the 'Nuts & Seeds' protein factor (highest vs lowest quintile of factor scores). No significant associations were found for the 'Grains', 'Processed Foods' and 'Legumes, Fruits & Vegetables' protein factors. Additional adjustments for the participants' vegetarian dietary pattern and nutrients related to cardiovascular disease outcomes did not change the results.

Conclusions

Associations between the 'Meat' and 'Nuts & Seeds' protein factors and cardiovascular outcomes were strong and could not be ascribed to other associated nutrients considered to be important for cardiovascular health. Healthy diets can be advocated based on protein sources, preferring low contributions of protein from meat and higher intakes of plant protein from nuts and seeds.

Serum amino acid profiles and risk of type 2 diabetes among Japanese adults in the Hitachi Health Study

Amino acids have emerged as novel biomarkers for predicting type 2 diabetes (T2D), but the epidemiologic data linking circulating amino acid profiles with T2D are sparse in Asian populations. We conducted a nested case-control study within a cohort of 4,754 nondiabetic Japanese employees who attended a comprehensive health checkup in 2008-2009 and agreed to provide blood samples. During a 5-year follow-up, incident T2D cases were ascertained based on plasma glucose, glycated hemoglobin, and self-report. Two controls matched to each case on sex, age, and the date of serum sampling were randomly selected by using density sampling, resulting in 284 cases and 560 controls with amino acid measures. High concentrations of valine, leucine, isoleucine, phenylalanine, tyrosine, alanine, glutamate, ornithine, and lysine were associated with an increased risk of incident T2D, in a linear manner. High glutamine concentrations were associated with a decreased risk of incident T2D. Further adjustment for the homeostasis model assessment of insulin resistance attenuated these associations. Overall, these amino acids may be novel useful biomarkers in the identification of people at risk of T2D before overt symptoms. Insulin resistance may account for or mediate the relationship between these amino acids and risk of incident T2D.

Do dietary amino acid ratios predict risk of incident hypertension among adults?

In the current study, we investigated the association between dietary amino acid ratios and the 3-year incidence of hypertension, conducted in the framework of the Tehran Lipid and Glucose Study with 4287 adults(41.9% men), aged 20-70 y. Dietary intakes of amino acids were assessed using a valid and reliable food frequency questionnaire and reported as percentage of protein. Then amino acid ratios including Leu.Ser/Thr.Trp, Leu/Trp, Leu/Thr, and Ser/Thr were calculated. We identified 429(10%) cases of hypertension during 3.1 y of follow up. The adjusted OR of the highest quartile of dietary Leu.Ser/Thr.Trp intake was 1.48 (95%CI:1.04-2.09, P for trend:0.02) compared with the lowest one. Furthermore, the OR of hypertension in the highest, compared with the lowest quartile of the leu/Thr ratio(2.19 vs 2.02) was 1.46(1.01-2.12), P for trend = 0.07. Our findings suggest that high dietary intakes of Leu.Ser/Thr.Trp ratio were associated with higher risk of incident hypertension and BP levels.

Mortality after admission for heart failure in the UK compared with Japan

Objective

Mortality amongst patients hospitalised for heart failure (HHF) in Western and Asian countries may differ, but this has not been investigated using individual patient-level data (IPLD). We sought to remedy this through rigorous statistical analysis of HHF registries and variable selection from a systematic literature review.

Methods and results

IPLD from registries of HHF in Japan (n=3781) and the UK (n=894) were obtained. A systematic literature review identified 23 models for predicting outcome of HHF. Five variables appearing in 10 or more reports were strongly related to prognosis (systolic blood pressure, serum sodium concentration, age, blood urea nitrogen and creatinine). To compare mortality in the UK and Japan, variables were imputed in a propensity model using inverse probability of treatment weighting (IPTW) and IPTW with logistic regression (doubly robust IPTW). Overall, patients in the UK were sicker and in-patient and post-discharge mortalities were greater, suggesting that the threshold for hospital admission was higher. Covariate-adjusted in-hospital mortality was similar in the UK and Japan (IPTW OR: 1.14, 95% CI 0.70 to 1.86), but 180-day postdischarge mortality was substantially higher in the UK (doubly robust IPTW OR: 2.33, 95% CI 1.58 to 3.43).

Conclusions

Despite robust methods to adjust for differences in patient characteristics and disease severity, HHF patients in the UK have roughly twice the mortality at 180 days compared with those in Japan. Similar analyses should be done using other data sets and in other countries to determine the consistency of these findings and identify factors that might inform healthcare policy and improve outcomes.

Dietary amino acids and incidence of hypertension: A principle component analysis approach

The current study aimed to investigate the association between dietary amino acid patterns and incidence of hypertension, using principal components factor analyses. This study was conducted within the framework of Tehran Lipid and Glucose Study on 4288 adults, who were free of hypertension at baseline (2008–2011) and were followed for three years (2011–2014). Principal component factor analyses were conducted based on eight amino acid groups and three amino acid patterns were extracted. The first pattern was characterized by branched chain, aromatic, and alcoholic amino acids, and proline. Acidic amino acids and proline were highly loaded in the second pattern and the third was characterized by sulphuric and small amino acids. Adjusted odds ratio of the highest quartile of the first pattern was 1.83 (95%CI: 1.21–2.77, P for trend = 0.002) compared to the lowest one. The first pattern had high positive correlation with dietary intakes of animal protein and dairy, but was negatively correlated with plant protein, fruit, and vegetable. There was no significant association for the second and third patterns. Findings indicate that the dietary amino acid pattern, rich in branched chain, aromatic, and alcoholic amino acids, and proline could increase the risk of hypertension.

High dietary intake of aromatic amino acids increases risk of hypertension

Recent studies investigated the relation between amino acids and blood pressure. Our aim was to examine the association between intake of aromatic amino acids (AAAs) and risk of hypertension. A total of 4288 individuals, aged 20-70 years, participants of the Tehran Lipid and Glucose Study, who were free of hypertension at baseline (2008-2011), were followed for 3 years (2011-2014). Average intakes of AAAs including phenylalanine, tyrosine, and tryptophan were collected using a valid and reliable food frequency questionnaire at baseline. Adjusted logistic regression models were used to report odds ratio (OR) of hypertension across quartiles of AAAs. At the end of follow-up, 429 (10%) hypertension cases were ascertained. The adjusted OR of hypertension for percentage of AAAs from total protein intakes was 1.63 (95% confidence interval, 1.06-2.50; P for trend: .03) when comparing the highest quartile to the lowest. Furthermore, in the adjusted analyses, a statistically significant positive relationship was observed between the highest versus the lowest quartile intake of phenylalanine (OR = 1.66; 95% confidence interval, 1.14-2.47; P for trend: .03). However, there was no significant association of tyrosine and tryptophan intakes with hypertension risk. Our data suggest that AAAs may increase the risk of incident hypertension.

Dietary Protein Consumption and the Risk of Type 2 Diabetes: A Systematic Review and Meta-Analysis of Cohort Studies

Recently, some studies have focused on the relationship between dietary protein intake and the risk of type 2 diabetes mellitus (T2DM), but the conclusions have been inconsistent. Therefore, in this paper, a systematic review and meta-analysis of cohort studies regarding protein consumption and T2DM risk are conducted in order to present the association between them. We searched the PubMed and Embase databases for cohort studies on dietary protein, high-protein food consumption and risk of T2DM, up to July 2017. A summary of relative risks was compiled by the fixed-effect model or random-effect model. Eleven cohort studies regarded protein intake and T2DM (52,637 cases among 483,174 participants). The summary RR and 95% CI (Confidence Interval) of T2DM was 1.12 (1.08–1.17) in all subjects, 1.13 (1.04–1.24) in men, and 1.09 (1.04–1.15) in women for total protein; 1.14 (1.09–1.19) in all subjects, 1.23 (1.09–1.38) in men, and 1.11 (1.03–1.19) in women for animal protein; 0.96 (0.88–1.06) in all subjects, 0.98 (0.72–1.34) in men, and 0.92 (0.86–0.98) in women for plant protein. We also compared the association between different food sources of protein and the risk of T2DM. The summary RR (Relative Risk) and 95% CI of T2DM was 1.22 (1.09–1.36) for red meat, 1.39 (1.29–1.49) for processed meat, 1.03 (0.89–1.17) for fish, 1.03 (0.64–1.67) for egg, 0.89 (0.84–0.94) for total dairy products, 0.87 (0.78–0.96) for whole milk, 0.83 (0.70–0.98) for yogurt, 0.74 (0.59–0.93) in women for soy. This meta-analysis shows that total protein and animal protein could increase the risk of T2DM in both males and females, and plant protein decreases the risk of T2DM in females. The association between high-protein food types and T2DM are also different. Red meat and processed meat are risk factors of T2DM, and soy, dairy and dairy products are the protective factors of T2DM. Egg and fish intake are not associated with a decreased risk of T2DM. This research indicates the type of dietary protein and food sources of protein that should be considered for the prevention of diabetes.

Metabolic phenotyping for discovery of urinary biomarkers of diet, xenobiotics and blood pressure in the INTERMAP Study: an overview

The etiopathogenesis of cardiovascular diseases (CVDs) is multifactorial. Adverse blood pressure (BP) is a major independent risk factor for epidemic CVD affecting ~40% of the adult population worldwide and resulting in significant morbidity and mortality. Metabolic phenotyping of biological fluids has proven its application in characterizing low-molecular-weight metabolites providing novel insights into gene-environmental-gut microbiome interaction in relation to a disease state. In this review, we synthesize key results from the INTERnational study of MAcro/micronutrients and blood Pressure (INTERMAP) Study, a cross-sectional epidemiologic study of 4680 men and women aged 40-59 years from Japan, the People's Republic of China, the United Kingdom and the United States. We describe the advancements we have made regarding the following: (1) analytical techniques for high-throughput metabolic phenotyping; (2) statistical analyses for biomarker identification; (3) discovery of unique food-specific biomarkers; and (4) application of metabolome-wide association studies to gain a better understanding into the molecular mechanisms of cross-cultural and regional BP differences.

Dietary protein intake and risk of type 2 diabetes: results from the Melbourne Collaborative Cohort Study and a meta-analysis of prospective studies

BACKGROUND

Reported associations between protein intake from different sources and type 2 diabetes (T2D) have been inconsistent.

OBJECTIVE

We prospectively examined the relations of total, animal, and plant protein intakes with incident T2D.

DESIGN

We followed 21,523 participants (women: 61.7%) between 1990 and 2007 from the Melbourne Collaborative Cohort Study who were free of diabetes, cardiovascular disease, cancer, and kidney stones at baseline. We also conducted a meta-analysis that included the results from our cohort and from 10 previous prospective studies.

RESULTS

A total of 929 new cases (4.3%) of T2D were documented during a mean of 11.7 y of follow-up. Multivariate-adjusted ORs for incident T2D in the highest compared with lowest quintiles of total and animal protein intakes as percentages of energy were 1.23 (95% CI: 0.96, 1.56; P-trend = 0.029) and 1.29 (95% CI: 0.99, 1.67; P-trend = 0.014), respectively. These associations appeared to be greater in men and in participants with normal baseline plasma glucose, body mass index, or blood pressure. Plant protein intake was inversely associated with incident T2D in women only (OR; 0.60; 95% CI: 0.37, 0.99). In the meta-analysis of 11 prospective cohort studies with 505,624 participants and 37,918 T2D cases (follow-up range: 5-24 y), pooled RRs for the comparison of the highest with lowest categories of total, animal, and plant protein intakes were 1.09 (95% CI: 1.06, 1.13), 1.19 (95% CI: 1.11, 1.28), and 0.95 (95% CI: 0.89, 1.02), respectively. Associations between animal protein intake and T2D were similar across sex, geographic region, length of follow-up, study quality, and method of expressing protein intake. An inverse association between plant protein intake and T2D was observed in women (RR: 0.93; 95% CI: 0.85, 1.00) and in US populations (RR: 0.91; 95% CI: 0.84, 0.97).

CONCLUSION

Higher intakes of total and animal protein were both associated with increased risks of T2D, whereas higher plant protein intake tended to be associated with lower risk of T2D.

An Update on Nutrients and Blood Pressure

Adverse blood pressure (BP) is a major independent risk factor for epidemic cardiovascular diseases affecting almost one-quarter of the adult population worldwide. Dietary intake is a major determinant in the development and progression of high BP. Lifestyle modifications, including recommended dietary guidelines, are advocated by the American Society of Hypertension, the International Society of Hypertension, the Japanese Society of Hypertension, and many other organisations for treating all hypertensive people, prior to initiating drug therapy and as an adjunct to medication in persons already on drug therapy. Lifestyle modification can also reduce high BP and prevent development of hypertension. This review synthesizes results from the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP), a cross-sectional epidemiological study of 4,680 men and women aged 40-59 years from Japan, the People's Republic of China, the United Kingdom, and the United States, published over the past few years on cross cultural BP differences. INTERMAP has previously reported that intakes of vegetable protein, glutamic acid, total and insoluble fibre, total polyunsaturated fatty acid and linoleic acid, total n-3 fatty acid and linolenic acid, phosphorus, calcium, magnesium, and non-heme iron were inversely related to BP. Direct associations of sugars (fructose, glucose, and sucrose) and sugar-sweetened beverages (especially combined with high sodium intake), cholesterol, glycine, alanine, and oleic acid from animal sources with BP were also reported by the INTERMAP Study.

Prevalence of hypertension and associated risk factors in Chinese Jing compared with Mulao populations

OBJECTIVE

*These authors contributed equally to this work. At present, they work at the Hezhou People's Hospital, Hezhou, China.To retrospectively compare differences in the prevalence of hypertension and associated risk factors between the Chinese Jing and Mulao populations.

METHODS

Subjects of Jing and Mulao ethnicities were surveyed using stratified randomized sampling. Demography, diet and lifestyle data were collected using standardized questionnaires. Several anthropometric parameters, blood pressure (BP) levels and serum lipid concentrations were obtained.

RESULTS

Data from 915 Jing and 911 Mulao subjects aged ≥ 35 years were included. Diastolic BP levels and prevalence of hypertension were lower, but prevalence of isolated systolic hypertension was higher, in the Jing compared with the Mulao population. Prevalence of hypertension in the age 60-69 years, body mass index (BMI) > 24 kg/m(2), and smoker subgroups was lower in the Jing compared with the Mulao populations. Prevalence of hypertension correlated with age, cigarette smoking, triglyceride level, waist circumference, sodium intake and total dietary fibre in the Jing population; hypertension prevalence also correlated with age, triglyceride level, BMI, total fat, sodium intake and total dietary fibre in the Mulao population (unconditional logistic regression analyses).

CONCLUSIONS

Prevalence of hypertension and associated risk factors were different between the two ethnic minorities, which might result from the combined effects of differences in their geographic, dietary, lifestyle, and genetic backgrounds.

Amino Acid Intakes Are Inversely Associated with Arterial Stiffness and Central Blood Pressure in Women

BACKGROUND

Although data suggest that intakes of total protein and specific amino acids (AAs) reduce blood pressure, data on other cardiovascular disease risk factors are limited.

OBJECTIVE

We examined associations between intakes of AAs with known mechanistic links to cardiovascular health and direct measures of arterial stiffness, central blood pressure, and atherosclerosis.

METHODS

In a cross-sectional study of 1898 female twins aged 18-75 y from the TwinsUK registry, intakes of 7 cardioprotective AAs (arginine, cysteine, glutamic acid, glycine, histidine, leucine, and tyrosine) were calculated from food-frequency questionnaires. Direct measures of arterial stiffness and atherosclerosis included central systolic blood pressure (cSBP), mean arterial pressure (MAP), augmentation index (AI), pulse wave velocity (PWV), and intima-media thickness (IMT). ANCOVA was used to assess the associations between endpoints of arterial stiffness and intake (per quintile), adjusting for potential confounders.

RESULTS

In multivariable analyses, higher intakes of total protein and 7 potentially cardioprotective AAs were associated with lower cSBP, MAP, and PWV. Higher intakes of glutamic acid, leucine, and tyrosine were most strongly associated with PWV, with respective differences of -0.4 ± 0.2 m/s (P-trend = 0.02), -0.4 ± 0.2 m/s (P-trend = 0.03), and -0.4 ± 0.2 m/s (P-trend = 0.03), comparing extreme quintiles. There was a significant interaction between AA intakes and protein source, and higher intakes of AAs from vegetable sources were associated with lower central blood pressure and AI. Higher intakes of glutamic acid, leucine, and tyrosine from animal sources were associated with lower PWV.

CONCLUSIONS

These data provide evidence to suggest that intakes of several AAs are associated with cardiovascular benefits beyond blood pressure reduction in healthy women. The magnitude of the observed associations was similar to those previously reported for other lifestyle factors. Increasing intakes of these AAs could be an important and readily achievable way to reduce cardiovascular disease risk.

Dietary protein and amino acids intake and its relationship with blood pressure in adolescents: the HELENA STUDY

OBJECTIVE

To analyze the association between dietary protein and amino acids intake and systolic (SBP) and diastolic (DBP) blood pressure in European adolescents.

METHODS

Participants were from the cross-sectional study performed in Europe, Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA study; n = 1605; 12.5-17.5 years; 833 girls) selected by complex sampling. The associations between dietary protein and amino acids intake and SBP/DBP were examined by multilevel linear regression models (context variable by school); the analysis being stratified by sex. Cities, seasonality, age, socioeconomic level, parental education level, body mass index, waist circumference, Tanner stage and physical activity were used as covariates.

RESULTS

In boys, we found an inverse association between protein (animal and vegetable) intake and DBP; and a positive association between histidine and SBP. In girls, we observed a positive association among tryptophan, histidine with SBP and methionine with DBP. On the other hand, we observed an inverse association between tyrosine and both SBP and DBP levels in girls.

CONCLUSIONS

The association between amino acids and BP levels is controversial and depends on the type of amino acids, and protein intake can help control the DBP in boys.

Dietary intakes of glutamic acid and glycine are associated with stroke mortality in Japanese adults

BACKGROUND

Dietary intakes of glutamic acid and glycine have been reported to be associated with blood pressure. However, the link between intakes of these amino acids and stroke has not been studied.

OBJECTIVE

We aimed to examine the association between glutamic acid and glycine intakes and the risk of mortality from stroke in a population-based cohort study in Japan.

METHODS

The analyses included 29,079 residents (13,355 men and 15,724 women) of Takayama City, Japan, who were aged 35-101 y and enrolled in 1992. Their body mass index ranged from 9.9 to 57.4 kg/m(2). Their diets were assessed by a validated food frequency questionnaire. Deaths from stroke were ascertained over 16 y.

RESULTS

During follow-up, 677 deaths from stroke (328 men and 349 women) were identified. A high intake of glutamic acid in terms of a percentage of total protein was significantly associated with a decreased risk of mortality from total stroke in women after controlling for covariates; the HR (95% CI) for the highest vs. lowest quartile was 0.72 (0.53, 0.98; P-trend: 0.03). Glycine intake was significantly associated with an increased risk of mortality from total and ischemic stroke in men without history of hypertension at baseline; the HRs (95% CIs) for the highest vs. lowest tertile were 1.60 (0.97, 2.51; P-trend: 0.03) and 1.88 (1.01, 3.52; P-trend: 0.02), respectively. There was no association between animal or vegetable protein intake and mortality from total and any subtype of stroke.

CONCLUSION

The data suggest that glutamic acid and glycine intakes may be associated with risk of stroke mortality. Given that this is an initial observation, our results need to be confirmed.