Project description:BackgroundData are available that indicate an independent inverse relationship of dietary vegetable protein to the blood pressure (BP) of individuals. Here, we assess whether BP is associated with glutamic acid intake (the predominant dietary amino acid, especially in vegetable protein) and with each of 4 other amino acids that are relatively higher in vegetable than animal protein (proline, phenylalanine, serine, and cystine).Methods and resultsThis was a cross-sectional epidemiological study with 4680 persons 40 to 59 years of age from 17 random population samples in China, Japan, the United Kingdom, and the United States. BP was measured 8 times at 4 visits; dietary data (83 nutrients, 18 amino acids) were obtained from 4 standardized, multipass, 24-hour dietary recalls and 2 timed 24-hour urine collections. Dietary glutamic acid (percentage of total protein intake) was inversely related to BP. Across multivariate regression models (model 1, which controlled for age, gender, and sample, through model 5, which controlled for 16 possible nonnutrient and nutrient confounders), estimated average BP differences associated with a glutamic acid intake that was higher by 4.72% of total dietary protein (2 SD) were -1.5 to -3.0 mm Hg systolic and -1.0 to -1.6 mm Hg diastolic (z scores -2.15 to -5.11). Results were similar for the glutamic acid-BP relationship with each of the other amino acids also in the model; eg, with control for 15 variables plus proline, systolic/diastolic pressure differences were -2.7/-2.0 mm Hg (z scores -2.51, -2.82). In these 2-amino acid models, higher intake (by 2 SD) of each of the other amino acids was associated with small BP differences and z scores.ConclusionsDietary glutamic acid may have independent BP-lowering effects, which may contribute to the inverse relation of vegetable protein to BP.
Project description:Pre-clinical studies show that dietary protein restriction (DPR) improves healthspan and retards many age-related diseases such as type 2 diabetes. While mouse studies have shown that restriction of certain essential amino acids is required for this response, less is known about which amino acids are affected by DPR in humans. Here, using a within-subjects diet design, we examined the effects of dietary protein restriction in the fasted state, as well as acutely after meal feeding, on blood plasma amino acid levels. While very few amino acids were affected by DPR in the fasted state, several proteinogenic AAs such as isoleucine, leucine, lysine, phenylalanine, threonine, tyrosine, and valine were lower in the meal-fed state with DPR. In addition, the non-proteinogenic AAs such as 1- and 3-methyl-histidine were also lower with meal feeding during DPR. Lastly, using in silico predictions of the most limiting essential AAs compared with human exome AA usage, we demonstrate that leucine, methionine, and threonine are potentially the most limiting essential AAs with DPR. In summary, acute meal feeding allows more accurate determination of which AAs are affected by dietary interventions, with most essential AAs lowered by DPR.
Project description:High dietary sodium intake triggers increased blood pressure (BP). Animal studies show that dietary salt loading results in dermal Na+ accumulation and lymphangiogenesis mediated by VEGF-C (vascular endothelial growth factor C), both attenuating the rise in BP. Our objective was to determine whether these mechanisms function in humans. We assessed skin electrolytes, BP, and plasma VEGF-C in 48 healthy participants randomized to placebo (70 mmol sodium/d) and slow sodium (200 mmol/d) for 7 days. Skin Na+ and K+ concentrations were measured in mg/g of wet tissue and expressed as the ratio Na+:K+ to correct for variability in sample hydration. Skin Na+:K+ increased between placebo and slow sodium phases (2.91±0.08 versus 3.12±0.09; P=0.01). In post hoc analysis, there was a suggestion of a sex-specific effect, with a significant increase in skin Na+:K+ in men (2.59±0.09 versus 2.88±0.12; P=0.008) but not women (3.23±0.10 versus 3.36±0.12; P=0.31). Women showed a significant increase in 24-hour mean BP with salt loading (93±1 versus 91±1 mm Hg; P<0.001) while men did not (96±2 versus 96±2 mm Hg; P=0.91). Skin Na+:K+ correlated with BP, stroke volume, and peripheral vascular resistance in men but not in women. No change was noted in plasma VEGF-C. These findings suggest that the skin may buffer dietary Na+, reducing the hemodynamic consequences of increased salt, and this may be influenced by sex.
Project description:BackgroundTo identify novel metabolites associated with salt sensitivity of blood pressure (SSBP) in Chinese Han population.MethodsA case-control study was conducted with 25 salt sensitive (SS) and 26 salt resistant (SR) participants, which was selected from the Systems Epidemiology Study on Salt Sensitivity of Blood Pressure (EpiSS) study. The modified Sullivan's acute oral saline load and diuresis shrinkage test (MSAOSL-DST) was conducted to identify SS. Untargeted, ultra-high performance liquid chromatograph-high resolution mass spectrometer (UPLC-HRMS) was conducted and orthogonal partial least squares-discriminate analysis (OPLS-DA) and multivariable logistic regression model were used to screen the metabolites related to SS, mixed linear regressions models were used to examined the association of SSBP with metabolites during saline load period and diuresis shrinkage period. Receiver operating characteristic (ROC) curve analysis was performed. The area under the curve's (AUC) sensitivity and specificity were calculated to identified metabolites biomarkers for SS.ResultsThere were 39 differentially expressed metabolites (DE-metabolites) between SS and SR. Thirty-five and four of DE-metabolites were inversely or positively associated with SS, respectively. Four biochemical pathways demonstrated significant enrichment for identified metabolites. In single-metabolite analyses, L-Glutamine displayed the best diagnostic performance (AUC = 0.88, 95% CI: 0.78-0.97). In multi-metabolites analyses, L-Glutamine + Cholesterol ester 22:5n6 combination showed the best diagnostic performance (AUC = 0.96, 95% CI: 0.91-1.00). Adjusted for traditional risk factors, L-Glutamine and Cholesterol ester 22:5n6 explained an additional 38.3% of SS susceptibility.ConclusionsThis study provide potential evidence for clarifying the mechanism of SS and provide novel biological insights into salt sensitive hypertension.