Plasma concentrations and ACE-inhibitory effects of tryptophan-containing peptides from whey protein hydrolysate in healthy volunteers

Impact of Quantity and Type of Dietary Protein on Cardiovascular Disease Risk Factors Using Standard and Network Meta-analyses of Randomized Controlled Trials

CONTEXT

Higher protein diets (HPDs) have shown favorable outcomes on weight maintenance and body-composition management; however, their protective effects against cardiovascular diseases (CVDs) remain uncertain and contentious. Furthermore, it is important to consider the influence of other macronutrients in the diet and type of dietary protein when studying HPDs, because this aspect has been overlooked in previous studies.

OBJECTIVE

We assessed the impacts of quantity and type of dietary protein on CVD risk factors.

DATA SOURCES

A database search was conducted in PubMed, Embase, CINAHL, Web of Science, and Cochrane Library and a total of 100 articles met the eligibility criteria.

DATA EXTRACTION

Extracted data from 100 articles were analyzed using standard meta-analysis, and 41 articles were also analyzed using network meta-analysis.

DATA ANALYSIS

In the standard meta-analysis, an HPD had significant favorable effects on systolic blood pressure (SBP) (mean difference [MD] = -1.51 mmHg; 95% CI: -2.77, -0.25), diastolic blood pressure (DBP) (MD = -1.08 mmHg; 95% CI: -1.81, -0.35), and flow-mediated dilation (MD = 0.78%; 95% CI: 0.09, 1.47) compared with lower protein diets. The further network meta-analysis supported that the high-protein, high-carbohydrate, low-fat diet was the most recommended diet to ensure a maximum decrease in SBP, DBP, total cholesterol (TC), and low-density-lipoprotein cholesterol (LDL-C). In comparison to animal-protein-rich diets, plant-protein-rich diets (PPRs) exhibited a significant favorable effects on improving TC (MD = -0.12 mmol/L; 95% CI: -0.19, -0.05), triglyceride (MD = -0.05 mmol/L; 95% CI: -0.09, -0.01), LDL-C (MD = -0.11 mmol/L; 95% CI: -0.18, -0.04), and high-density-lipoprotein cholesterol (MD = 0.03 mmol/L; 95% CI: 0.02, 0.04) levels.

CONCLUSION

Consumption of HPDs and PPRs supports improvements in vascular health and lipid-lipoprotein profiles, respectively. Furthermore, macronutrient composition should be carefully designed in the dietary approach to maximize the effectiveness of HPDs in improving CVD risk factors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022369931.

Association between serum albumin concentration change trajectory and risk of hypertension: a cohort study in China

Background

We sought to assess the risk of hypertension based on the trajectory of changes in serum albumin concentrations.

Methods

A total of 11,946 nonhypertension adults aged 30-60 years who underwent at least 3 medical examinations between 2009 and 2016 were included in this study. Group-based trajectory models were obtained for 4 category groups, and logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for each category group of serum albumin concentration and the risk of hypertension.

Results

During a mean follow-up period of 4.30 years, 1,537 hypertension events occurred in 11,946 subjects without hypertension. A high stable trajectory of serum albumin concentrations (OR, 0.70, 95% CI, 0.51-0.96) was associated with a significantly lower risk of developing hypertension. The results of the sensitivity analysis of the high stable trajectory (OR, 0.64, 95% CI, 0.43-0.96) remained statistically significant. Subjects with normal weight and those ≥45 years of age had a significantly lower risk of hypertension at moderate increase (P = 0.053 or 0.026) and high stable trajectories (P = 0.011 or 0.016). In males and overweight subjects, the risk of hypertension was significantly lower in the high stable trajectory (P = 0.038 or 0.044).

Conclusion

In this study, we found that moderate increase in serum albumin concentrations and a high stable trajectory were significantly associated with a reduced risk of hypertension in subjects aged ≥45 years and those with normal weight and that high stable serum albumin concentrations were significantly associated with a reduced risk of hypertension in males and overweight subjects.

Bioactive peptides in hydrolysates of bovine and camel milk proteins: A review of studies on peptides that reduce blood pressure, improve glucose homeostasis, and inhibit pathogen adhesion

The prevalence of diet-related chronic conditions including hypertension and cardiovascular disease, and diabetes mellitus has increased worldwide. Research regarding the use of food-derived bioactive peptides as an alternative strategy to mitigate chronic diseases is on the rise. Milk is recognized as one of the main dietary protein sources for health beneficial bioactive compounds. Hundreds of in vitro studies have suggested that milk-derived bioactive peptides offer multiple biological and physiological benefits, and some but not all were confirmed in vivo with animal models for hypertension, hyperglycemia, and pathogen adhesion. However, only a limited number of health benefits have been confirmed by randomized clinical trials. This review provides an overview of the current clinical studies that target hypertension, postprandial hyperglycemic, and adhesion of enteric pathogen with bioactive peptides derived from bovine and camel milk, with a focus on the factors affecting the efficacy of orally ingested products.

Whey proteins as a functional food: Health effects, functional properties, and applications in food

Functional foods are defined as foods and ingredients that exhibit health benefits beyond their nutritional value. Research on functional foods is increasing rapidly as they may help prevent and manage some non-communicable diseases. Whey proteins are recognized as a high-quality nutrient source and known to contain some bioactive components. They are rich in essential amino acids such as cysteine, branched-chain amino acids such as leucine, valine, and isoleucine, and bioactive peptides. Whey proteins look promising as a potential functional food, given its antioxidant, anti-inflammatory, blood pressure lowering, anti-obesity, and appetite suppressing effects that is discussed in the literature. Whey proteins also show functional properties that play an essential role in food processing as an emulsifier, fat-replacer, gelling and encapsulating agent and are known to improve sensory and textural characteristics of food. This review focuses on the functional food aspects of whey proteins, associated health effects, and current food applications.

Bioactive food-derived peptides for functional nutrition: Effect of fortification, processing and storage on peptide stability and bioactivity within food matrices

New challenges in food production and processing are appearing due to increasing global population and the purpose of achieving a sustainable food system. Bioactive peptides obtained from food proteins can be employed to prevent or pre-treat several diseases such as diabetes, cardiovascular diseases, inflammation, thrombosis, cancer, etc. Research on the bioactivity of protein hydrolysates is very extensive, especially in vitro tests, although there are also tests in animal models and in humans studies designed to verify their efficacy. However, there is very little published literature on the functionality of these protein hydrolysates as an ingredient in food matrices, as well as the effect that thermal or non-thermal processing, and storage may have on the bioactivity of these bioactive peptides. This review aims to summarize the published literature on protein hydrolysates as a functional ingredient including processing, storage and simulated gastrointestinal digestion regarding the bioactivity of these peptides inside food matrices.

Stability and bioactivity of peptides in food matrices based on processing conditions

Bioactive peptides (BPs) generated from food proteins can serve therapeutic purposes against degenerative and cardiovascular diseases such as inflammation, diabetes, and cancer. There are numerous reports on the in vitro, animal, and human studies of BPs, but not as much information on the stability and bioactivity of these peptides when incorporated in food matrices. The effects of heat and non-heat processing of the food products, and storage on the bioactivity of the BPs, are also lacking. To this end, we describe the production of BPs in this review, followed by the food processing conditions that affect their storage bioactivity in the food matrices. As this area of research is open for industrial innovation, we conclude that novel analytical methods targeting the interactions of BPs with other components in food matrices would be greatly significant while elucidating their overall bioactivity before, during and after processing.

Bioactive Peptides: An Understanding from Current Screening Methodology

Bioactive peptides with high potency against numerous human disorders have been regarded as a promising therapy in disease control. These peptides could be released from various dietary protein sources through hydrolysis processing using physical conditions, chemical agents, microbial fermentation, or enzymatic digestions. Considering the diversity of the original proteins and the complexity of the multiple structural peptides that existed in the hydrolysis mixture, the screening of bioactive peptides will be a challenge task. Well-organized and well-designed methods are necessarily required to enhance the efficiency of studying the potential peptides. This article, hence, provides an overview of bioactive peptides with an emphasis on the current strategy used for screening and characterization methods. Moreover, the understanding of the biological activities of peptides, mechanism inhibitions, and the interaction of the complex of peptide–enzyme is commonly evaluated using specific in vitro assays and molecular docking analysis.

Bioactive Peptides: From Basic Research to Clinical Trials and Commercialization

Chronic diseases, including metabolic diseases, have become a worldwide public health issue. Research regarding the use of bioactive peptides or protein hydrolysates derived from food, as the diet-based strategies for the prevention and mitigation of chronic diseases, has increased exponentially in the past decades. Numerous in vitro and in vivo studies report the efficacy and safety of food-derived bioactive peptides and protein hydrolysates as antihypertensive, anti-inflammatory, antidiabetic, and antioxidant agents. However, despite promising preclinical results, an inadequate understanding of their mechanisms of action and pharmacokinetics restrict their clinical translation. Commercialization of bioactive peptides can be further hindered due to scarce information regarding their efficacy, safety, bitter taste, as well as the lack of a cost-effective method of production. This review provides an overview of the current clinical evidence and challenges to commercial applications of food-derived bioactive peptides and protein hydrolysates for the prevention and alleviation of chronic diseases.

Potential Relevance of Bioactive Peptides in Sports Nutrition

Bioactive peptides are physiologically active peptides mostly derived from proteins following gastrointestinal digestion, fermentation or hydrolysis by proteolytic enzymes. It has been shown that bioactive peptides can be resorbed in their intact form and have repeatedly been shown to have a positive effect on health-related parameters such as hypertension, dyslipoproteinemia, inflammation and oxidative stress. In recent years, there has been increasing evidence that biologically active peptides could also play an important role in sports nutrition. Current studies have shown that bioactive peptides could have a positive impact on changes in body composition and muscular performance, reduce muscle damage following exercise and induce beneficial adaptions within the connective tissue. In the following overview, potential mechanisms as well as possible limitations regarding the sports-related effect of bioactive peptides and their potential mechanisms are presented and discussed. In addition, practical applications will be discussed on how bioactive peptides can be integrated into a nutritional approach in sports to enhance athletic performance as well as prevent injuries and improve the rehabilitation process.

Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Higher protein (HP) diets may lead to lower cardiometabolic risk, compared to lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP versus LP diets on cardiometabolic risk factors in adults, using the totality of the current evidence from randomised controlled trials (RCTs).

METHODS

Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.

RESULTS

Fifty-seven articles reporting on 54 RCTs were included, involving 4344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m²), with a mean study duration of 18 weeks (range: 4 to 156 weeks). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.

CONCLUSIONS

Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.

Activity and bioavailability of food protein-derived angiotensin-I-converting enzyme-inhibitory peptides

Angiotensin-I-converting enzyme (ACE) inhibitory peptides are able to inhibit the activity of ACE, which is the key enzymatic factor mediating systemic hypertension. ACE-inhibitory peptides can be obtained from edible proteins and have the function of antihypertension. The amino acid sequences and the secondary structures of ACE-inhibitory peptides determine the inhibitory activities and stability. The resistance of ACE-inhibitory peptides to digestive enzymes and peptidase affect their antihypertensive bioactivity in vivo. In this paper, the mechanism of ACE-inhibition, sources of the inhibitory peptides, structure-activity relationships, stability during digestion, absorption and transportation of ACE-inhibitory peptides, and consumption of ACE-inhibitory peptides are reviewed, which provide guidance to the development of new functional foods and production of antihypertensive nutraceuticals and pharmaceuticals.

The Influence of Peptidases in Intestinal Brush Border Membranes on the Absorption of Oligopeptides from Whey Protein Hydrolysate: An Ex Vivo Study Using an Ussing Chamber

For many years, it was believed that only amino acids, dipeptides, and tripeptides could be absorbed and thus reach the bloodstream. Nowadays, the bioavailability of oligopeptides is also considered possible, leading to new research. This pilot study investigates the activity of brush border enzymes on undigested whey protein hydrolysate (WPH) and on simulated intestinal digested (ID) whey hydrolysate and the subsequent absorption of resultant peptides through the proximal jejunum of a 7-week old piglet setup in an Ussing chamber model. Amongst all samples taken, 884 oligopeptides were identified. The brush border peptidase activity was intense in the first 10 min of the experiment, producing several new peptides in the apical compartment. With respect to the ID substrate, 286 peptides were detected in the basolateral compartment after 120 min of enzyme activity, originating from β-lactoglobulin (60%) and β-casein (20%). Nevertheless, only 0.6 to 3.35% of any specific peptide could pass through the epithelial barrier and thus reach the basolateral compartment. This study demonstrates transepithelial jejunum absorption of whey oligopeptides in an ex vivo model. It also confirmed the proteolytic activity of brush border enzymes on these oligopeptides, giving birth to a myriad of new bioactive peptides available for absorption.