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

Association between diet and measures of arterial stiffness in type 1 diabetes - Focus on dietary patterns and macronutrient substitutions

BACKGROUND AND AIMS

Increased arterial stiffness contributes to diabetic vascular complications. We identified dietary factors related to arterial stiffness in individuals with type 1 diabetes, a population with high risk of cardiovascular disease.

METHODS AND RESULTS

Altogether, 612 participants (40% men, mean ± standard deviation age 45 ± 13 years) completed a validated diet questionnaire and underwent measurements of arterial stiffness. Of these, 470 additionally completed a food record. Exploratory factor analysis was applied to identify dietary patterns from the diet questionnaires, and nutrient intakes were calculated from food record entries. Arterial stiffness was measured by applanation tonometry. Of the seven dietary factors formed, the factor scores of "Full-fat cheese and eggs" and "Sweet" patterns were negatively associated with measures of arterial stiffness. In the multivariable macronutrient substitution models, favouring carbohydrates over fats was associated with higher aortic mean arterial pressure and aortic pulse wave velocity. When carbohydrates were consumed in place of proteins, higher aortic pulse pressure, aortic mean arterial pressure, and augmentation index were recorded. Replacing energy from alcohol with proteins, was associated with lower aortic pulse pressure, aortic mean arterial pressure, and augmentation index. Relative distributions of dietary fatty acids were neutral with respect to the measures of arterial stiffness.

CONCLUSION

The macronutrient distribution of the diet is likely to affect the resilience of the arteries. Our observations suggest that reducing energy intake from carbohydrates and alcohol may be beneficial. These observations, especially those dealing with dietary patterns, need to be confirmed in a longitudinal study.

Specific Amino Acids Affect Cardiovascular Diseases and Atherogenesis via Protection against Macrophage Foam Cell Formation: Review Article

The strong relationship between cardiovascular diseases (CVD), atherosclerosis, and endogenous or exogenous lipids has been recognized for decades, underestimating the contribution of other dietary components, such as amino acids, to the initiation of the underlying inflammatory disease. Recently, specific amino acids have been associated with incident cardiovascular disorders, suggesting their significant role in the pathogenesis of CVD. Special attention has been paid to the group of branched-chain amino acids (BCAA), leucine, isoleucine, and valine, since their plasma values are frequently found in high concentrations in individuals with CVD risk. Nevertheless, dietary BCAA, leucine in particular, have been associated with improved indicators of atherosclerosis. Therefore, their potential role in the process of atherogenesis and concomitant CVD development remains unclear. Macrophages play pivotal roles in the development of atherosclerosis. They can accumulate high amounts of circulating lipids, through a process known as macrophage foam cell formation, and initiate the atherogenesis process. We have recently screened for anti- or pro-atherogenic amino acids in the macrophage model system. Our study showed that glycine, cysteine, alanine, leucine, glutamate, and glutamine significantly affected macrophage atherogenicity mainly through modulation of the cellular triglyceride metabolism. The anti-atherogenic properties of glycine and leucine, and the pro-atherogenic effects of glutamine, were also confirmed in vivo. Further investigation is warranted to define the role of these amino acids in atherosclerosis and CVD, which may serve as a basis for the development of anti-atherogenic nutritional and therapeutic approaches.

Leucine supplementation attenuates macrophage foam-cell formation: Studies in humans, mice, and cultured macrophages

Whereas atherogenicity of dietary lipids has been largely studied, relatively little is known about the possible contribution of dietary amino acids to macrophage foam-cell formation, a hallmark of early atherogenesis. Recently, we showed that leucine has antiatherogenic properties in the macrophage model system. In this study, an in-depth investigation of the role of leucine in macrophage lipid metabolism was conducted by supplementing humans, mice, or cultured macrophages with leucine. Macrophage incubation with serum obtained from healthy adults supplemented with leucine (5 g/d, 3 weeks) significantly decreased cellular cholesterol mass by inhibiting the rate of cholesterol biosynthesis and increasing cholesterol efflux from macrophages. Similarly, leucine supplementation to C57BL/6 mice (8 weeks) resulted in decreased cholesterol content in their harvested peritoneal macrophages (MPM) in relation with reduced cholesterol biosynthesis rate. Studies in J774A.1 murine macrophages revealed that leucine dose-dependently decreased cellular cholesterol and triglyceride mass. Macrophages treated with leucine (0.2 mM) showed attenuated uptake of very low-density lipoproteins and triglyceride biosynthesis rate, with a concurrent down-regulation of diacylglycerol acyltransferase-1, a key enzyme catalyzing triglyceride biosynthesis in macrophages. Similar effects were observed when macrophages were treated with α-ketoisocaproate, a key leucine metabolite. Finally, both in vivo and in vitro leucine supplementation significantly improved macrophage mitochondrial respiration and ATP production. The above studies, conducted in human, mice, and cultured macrophages, highlight a protective role for leucine attenuating macrophage foam-cell formation by mechanisms related to the metabolism of cholesterol, triglycerides, and energy production. © 2018 BioFactors, 44(3):245-262, 2018.

Markers of arterial health could serve as accurate non-invasive predictors of human biological and chronological age

The decline in functional capacity is unavoidable consequence of the process of aging. While many anti-aging interventions have been proposed, clinical investigations into anti-aging medicine are limited by lack of reliable techniques for evaluating the rate of ageing. Here we present simple, accurate and cost-efficient techniques for estimation of human biological age, Male and Female Arterial Indices. We started with developing a model which accurately predicts chronological age. Using machine learning, we arrived on a set of four predictors, all of which reflect the functioning of the cardiovascular system. In Arterial Indices models, results of carotid artery duplex scan that show the thickness of the intima media complex and quantitatively describe the degree of stenosis are combined with pulse wave velocity and augmentation index measurements performed by applanation tonometry. In our cohort, the age of men was determined with MAE = 6.91 years (adjusted R-squared = 0.55), and the age of women with MAE = 5.87 years (adjusted R² = 0.69). The Epsilon-accuracies of age-predicting models were at 86.5% and 80% for women and men, respectively. Substantially higher differences between the predicted age and the calendar age were noted for patients with Type 2 Diabetes Mellitus (T2D) as compared to non-T2D controls, indicating that the model could serve as a good approximation for an elusive biological age. Notably, in females with chronological and biological ages mismatching by 5 or more years, significant increases in in Framingham CVD scores and lower levels of IGF-1 were observed.

Proposed Male and Female Arterial Indices derive biological age from the results of functional tests which do not require specialized laboratory equipment and, therefore, could be performed in hospitals and community health clinics.

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.

Contribution of dietary amino acids composition to incidence of cardiovascular outcomes: A prospective population-based study

BACKGROUND AND AIM

Considering the limited data on the cardiovascular effects of dietary amino acid intakes, we assessed possible association of dietary amino acids with the risk of cardiovascular (CVD) events in a prospective population-based study.

METHODS

Participants without CVD (n = 2369) were recruited from the Tehran Lipid and Glucose Study and were followed for a mean of 6.7 years. Dietary protein and amino acid intakes were assessed at baseline (2006-2008); demographic, lifestyle and biochemical variables were evaluated at baseline and follow-up examination (2012-2014). Multivariate Cox proportional hazard regression models, adjusted for potential confounders, were used to estimate risk of CVD across tertiles of dietary amino acids.

RESULTS

Mean total protein intake was 76.9 ± 27.5 g/d, and dietary protein had no significant association with the risk of CVD (HR = 1.23, 95% CI = 0.65-2.31, and HR = 0.52, 95% CI = 0.19-1.41, in the second and third tertiles, respectively). After adjustment of potential confounders, the amino acid pattern with higher load of glycine, cysteine, arginine and tryptophan, was negatively associated with CVD (HR = 0.28, 95% CI = 0.09-0.88, P for trend = 0.08). Higher intake of sulfur-containing amino acids (cysteine and methionine), and potentially cardioprotective amino acids (arginine, cysteine, glutamic acid, glycine, histidine, leucine and tyrosine) corresponded to 73% (HR = 0.27, 95% CI = 0.09-0.86) and 74% (HR = 0.26, 95% CI = 0.09-0.78) decreased risk of CVD events. Higher intake of glutamic acid and proline (% of dietary total protein) increased the risk of CVD (HR = 1.30, 95% CI = 1.03-1.64, and HR = 1.33, 95% CI = 1.10-1.60, respectively).

CONCLUSION

These novel data provide evidence to suggest that amino acid composition of diet may modify the risk of CVD events.

Saturated Fatty Acids and Cardiovascular Disease: Replacements for Saturated Fat to Reduce Cardiovascular Risk

Dietary recommendations to decrease the risk of cardiovascular disease (CVD) have focused on reducing intake of saturated fatty acids (SFA) for more than 50 years. While the 2015-2020 Dietary Guidelines for Americans advise substituting both monounsaturated and polyunsaturated fatty acids for SFA, evidence supports other nutrient substitutions that will also reduce CVD risk. For example, replacing SFA with whole grains, but not refined carbohydrates, reduces CVD risk. Replacing SFA with protein, especially plant protein, may also reduce CVD risk. While dairy fat (milk, cheese) is associated with a slightly lower CVD risk compared to meat, dairy fat results in a significantly greater CVD risk relative to unsaturated fatty acids. As research continues, we will refine our understanding of dietary patterns associated with lower CVD risk.

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.

Plant Protein Intake and Dietary Diversity Are Independently Associated with Nutrient Adequacy in French Adults

BACKGROUND

Plant protein intake, which is favorably associated with the intake of many nutrients, is a marker of a healthy diet. However, the higher nutrient adequacy of diets rich in plant protein may also originate from overarching factors associated with more healthful dietary behaviors, such as a greater dietary diversity.

OBJECTIVE

Our main objective was to determine whether the relation between plant protein intake and nutrient adequacy could be explained, at least in part, by an association with overall dietary diversity.

METHODS

We used data from 1330 adults participating in the French Nutrition and Health Survey [Etude Nationale Nutrition Santé (ENNS); 2006-2007]. With the use of global, integrative approaches, we assessed nutrient adequacy [by using the probabilistic PANDiet (Probability of Adequate Nutrient Intake) scoring system] and overall dietary diversity (by using a 100-point score that accounts for the relative number of subgroups consumed in 7 food groups). Linear multivariate modeling was used for the analysis.

RESULTS

We found a positive association between plant protein (but not total or animal protein) intake and dietary diversity (β = 0.08) and a strong positive association between dietary diversity and nutrient adequacy (β = 0.33). However, the association between plant protein intake and nutrient adequacy was not explained by dietary diversity (r = 0.38 and partial r = 0.36, P < 0.0001). In multivariate analysis, nutrient adequacy was positively associated with dietary diversity (β = 0.44) and plant (β = 0.37) and animal (β = 0.15) protein intakes. Associations persisted after adjustment for potential confounders (total energy, energy density, sex, body mass index, income, occupational status, educational level, region, season, and smoking status).

CONCLUSIONS

Overall dietary diversity is greater in French adults who consume more plant protein. Both plant protein intake and dietary diversity are associated with the nutrient adequacy of the diet. But the plant protein-nutrient adequacy association was not related to the relative overall diversity of the diet.