Encapsulation of short-chain bioactive peptides (BAPs) for gastrointestinal delivery: a review

The majority of known peptides with high bioactivity (BAPs) such as antihypertensive, antidiabetic, antioxidant, hypocholesterolemic, anti-inflammatory and antimicrobial actions, are short-chain sequences of less than ten amino acids. These short-chain BAPs of varying natural and synthetic origin must be bioaccessible to be capable of being adsorbed systemically upon oral administration to show their full range of bioactivity. However, in general, in vitro and in vivo studies have shown that gastrointestinal digestion reduces BAPs bioactivity unless they are protected from degradation by encapsulation. This review gives a critical analysis of short-chain BAP encapsulation and performance with regard to the oral delivery route. In particular, it focuses on short-chain BAPs with antihypertensive and antidiabetic activity and encapsulation methods via nanoparticles and microparticles. Also addressed are the different wall materials used to form these particles and their associated payloads and release kinetics, along with the current challenges and a perspective of the future applications of these systems.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Milk Antiviral Proteins and Derived Peptides against Zoonoses

Milk is renowned for its nutritional richness but also serves as a remarkable reservoir of bioactive compounds, particularly milk proteins and their derived peptides. Recent studies have showcased several robust antiviral activities of these proteins, evidencing promising potential within zoonotic viral diseases. While several publications focus on milk's bioactivities, antiviral peptides remain largely neglected in reviews. This knowledge is critical for identifying novel research directions and analyzing potential nutraceuticals within the One Health context. Our review aims to gather the existing scientific information on milk-derived antiviral proteins and peptides against several zoonotic viral diseases, and their possible mechanisms. Overall, in-depth research has increasingly revealed them as a promising and novel strategy against viruses, principally for those constituting a plausible pandemic threat. The underlying mechanisms of the bioactivity of milk's proteins include inhibiting viral entry and attachment to the host cells, blocking replication, or even viral inactivation via peptide-membrane interactions. Their marked versatility and effectiveness stand out compared to other antiviral peptides and can support future research and development in the post-COVID-19 era. Overall, our review helps to emphasize the importance of potentially effective milk-derived peptides, and their significance for veterinary and human medicines, along with the pharmaceutical, nutraceutical, and dairy industry.

Eugeniin improves cholesterol metabolism in HepG2 cells and Caco-2 cells

Considering the absence of prior studies on the cholesterol metabolism-improving effects of eugeniin, the present investigation aimed to explore the potential impact of eugeniin on cholesterol metabolism. This study sought to elucidate the molecular mechanisms involved in this process using HepG2 and Caco-2 cells treated with 5 µm eugeniin. The intracellular cholesterol levels in HepG2 and Caco-2 cells were significantly decreased in the 24-h eugeniin-treated group. The protein and messenger ribonucleic acid (mRNA) levels of the low-density lipoprotein receptor (LDLR) were increased, while 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase protein and mRNA levels were decreased in HepG2 cells 6 h of the eugeniin-treated group. Additionally, LDLR protein and mRNA levels were increased in HepG2 cells after 24 h of eugeniin treatment. In Caco-2, the protein and mRNA levels of ATP-binding cassette transporter 1 were increased after 24 h eugeniin treatment. This novel finding indicates that eugeniin improves cholesterol metabolism in human cell cultures.

The modulatory effects on enterohepatic cholesterol metabolism of novel cholesterol-lowering peptides from gastrointestinal digestion of Xuanwei ham

The aim of this study was to investigate the effects and mechanism of in vitro protein digestive products of Xuanwei ham with different ripening periods on cholesterol metabolism and hypercholesterolemia. The results showed that compared with other gastrointestinal digestion (GID) groups, the GID group of Xuanwei ham with 3-year ripening period (XWH3-GID) inhibited the expression of Niemann-Pick C1-like 1 (NPC1L1) and acetyl-CoA acetyltransferase 2 (ACAT2) through hepatocyte nuclear factor 1-alpha (HNF-1α), which in turn effectively inhibited cholesterol absorption in Caco-2 cell monolayers. Following absorption by Caco-2 cell monolayers, the XWH3-GID group suppressed the expression and secretion of proprotein convertase subtilisin/kexin type 9 (PCSK9) via HNF-1α, which enhanced the protein expression and fluorescence intensity of low density lipoprotein receptor (LDLR) on the HepG2 cell membrane, and thus promoted the uptake of low density lipoprotein (LDL). Importantly, three novel peptides (LFP, PKF and VPFP) derived from titin were identified after intestinal epithelial transport in the XWH3-GID group, which could exert cholesterol-lowering effects through inhibiting intestinal cholesterol absorption and promoting peripheral hepatic LDL uptake, and effectively ameliorate western diet-induced hypercholesterolemia in ApoE-/- mice. These results suggest that Xuanwei ham with 3-year ripening period can be used as a source of cholesterol-lowering peptides and has potential to intervene in hypercholesterolemia.

Bioactive milk peptides: an updated comprehensive overview and database

Partial digestion of milk proteins leads to the formation of numerous bioactive peptides. Previously, our research team thoroughly examined the decades of existing literature on milk bioactive peptides across species to construct the milk bioactive peptide database (MBPDB). Herein, we provide a comprehensive update to the data within the MBPDB and a review of the current state of research for each functional category from in vitro to animal and clinical studies, including angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, antioxidant, dipeptidyl peptidase (DPP)-IV inhibitory, opioid, anti-inflammatory, immunomodulatory, calcium absorption and bone health and anticancer activity. This information will help drive future research on the bioactivities of milk peptides.

Fermented milks with specific Lactobacillus spp. with potential cardioprotective effects

In vitro and in vivo studies have reported the potential cardioprotective effects of fermented milks (FM). The aim of the present study was to evaluate the inhibitory activities of angiotensin converting enzyme (ACE), thrombin enzyme (TI) and micellar solubility of cholesterol of FM after 24 and 48 h of fermentation with Limosilactobacillus fermentum (J20, J23, J28 and J38), Lactiplantibacillus plantarum (J25) or Lactiplantibacillus pentosus (J34 and J37) exposed to simulated gastrointestinal digestion. Results showed that FM with J20 and J23 at 48 h of fermentation presented significantly (p < 0.05) higher degree of hydrolysis than other FM, and were not significantly different (p > 0.05) between them. Conversely, peptide relative abundance was significantly (p < 0.05) higher in FM with J20 than FM with J23. Moreover, IC₅₀ (protein concentration necessary to inhibit enzyme activity by 50%) for ACE inhibition were 0.33 and 0.5 mg/mL for FM with J20 and J23, respectively. For TI inhibition, the IC₅₀ were 0.3 and 0.24 mg/mL for FM with J20 and J23, respectively. Results exhibited 51 and 74% inhibition of micellar solubility cholesterol for FM with J20 and J23, respectively. Therefore, these results showed that not only peptide abundance, but also specific peptides might be responsible for these potential cardioprotective effects.

Transportation of whey protein-derived peptides using Caco-2 cell model and identification of novel cholesterol-lowering peptides

Background

The increasing morbidity and mortality of cardiovascular disease have become a major factor in human death. Serum cholesterol is considered to be an important risk factor for inducing coronary heart disease, atherosclerosis and other cardiovascular diseases. To screen intestinal absorbable functional small peptides with cholesterol-lowering activity by enzymatic hydrolysis of whey protein and develop cholesterol-based functional food that may become a substitute for chemically synthesized drugs, providing new ideas for diseases caused by high cholesterol.

Objective

This study aimed to evaluate the cholesterol-lowering activity of intestinal absorbable whey protein-derived peptides hydrolyzed by alkaline protease, trypsin and chymotrypsin, respectively.

Method

The whey protein hydrolysates acquired by enzymatic hydrolysis under optimal conditions were purified by a hollow fiber ultrafiltration membrane with a molecular weight cutoff of 10 kDa. The fractions obtained by Sephadex G-10 gel filtration chromatography were transported through a Caco-2 cell monolayer. The transported peptides were detected in the basolateral aspect of Caco-2 cell monolayers using ultra- performance liquid chromatography-tandem mass spectrometry (UPLC-MS).

Results

His-Thr-Ser-Gly-Tyr (HTSGY), Ala-Val-Phe-Lys (AVFK) and Ala-Leu-Pro-Met (ALPM) were unreported peptides with cholesterol-lowering activity. The cholesterol-lowering activities of the three peptides did not change significantly during simulated gastrointestinal digestion.

Conclusion

This study not only provides theoretical support for the development of bioactive peptides that can be directly absorbed by the human body, but also provides new treatment ideas for hypercholesterolemia.

Novel Hypocholesterolemic Peptides Derived from Silver Carp Muscle: The Modulatory Effects on Enterohepatic Cholesterol Metabolism In Vitro and In Vivo

This research aimed to investigate the effect of silver carp hydrolysates (SCHs) on hypercholesterolemia and enterohepatic cholesterol metabolism. Results showed that in vitro gastrointestinal digestion products of Alcalase-SCH (GID-Alcalase) exhibited the highest inhibitory activity of cholesterol absorption mainly through downregulating the expression of essential genes related to cholesterol transport in a Caco-2 monolayer. After being absorbed by the Caco-2 monolayer, GID-Alcalase increased the low-density lipoprotein (LDL) uptake in HepG2 cells by enhancing the protein level of the LDL receptor (LDLR). The in vivo experiment showed that long-term intervention of Alcalase-SCH ameliorated hypercholesterolemia in ApoE^-/- mice fed with a Western diet (WD). After transepithelial transport, four novel peptides (TKY, LIL, FPK, and IAIM) were identified, and these peptides possessed dual hypocholesterolemic functions including inhibition of cholesterol absorption and promotion of peripheric LDL uptake. Our results indicated for the first time the potential of SCHs as functional food ingredients for the management of hypercholesterolemia.

Peptide profile of Parmigiano Reggiano cheese after simulated gastrointestinal digestion: From quality drivers to functional compounds

Time of ripening has a strong impact on shaping the valuable and recognizable characteristics of long-ripened types of cheese such as Parmigiano Reggiano (PR) due to the interrelationship between microbiota and proteolysis that occurs during ripening. The derived peptide profile is linked to cheese quality and represents the canvas for enzymes upon digestion, which could be responsible for the release of potentially bioactive peptides (BPs). In this study, we aimed at investigating the presence of BP in 72 PR cheese samples of different ripening times, from curd to 24 months of ripening, produced in six different dairies, and following their fate after simulated gastrointestinal digestion. A small number of peptide sequences sharing 100% similarity with known antimicrobial, antioxidant, and ACE-inhibitor sequences were found in PR cheeses, while a higher number of potential BPs were found after their simulated gastrointestinal digestion, in different amounts according to ripening time. Taking advantage of the complex organization of the sampling plan, we were able to follow the fate of peptides considered quality drivers during cheese ripening to their release as functional compounds upon digestion.

Recent findings on the cellular and molecular mechanisms of action of novel food-derived antihypertensive peptides

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Hypertension has remained a silent-killer.

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Novel peptides recently isolated from food proteins.

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Molecular mechanism of blood pressure-lowering: renin and ACE-inhibition, and beyond.

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Proposed molecular mechanisms for future research.

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Novel peptides are excellent candidates for nutraceutical development.

Hypertension impacts negatively on the quality of life of sufferers, and complications associated with uncontrolled hypertension are life-threatening. Hence, many research efforts are exploring the antihypertensive properties of bioactive peptides derived from food proteins using in vitro ACE-inhibitory assay, experimentally-induced and spontaneous hypertensive rats, normotensive and hypertensive human models. In this study, the cellular and molecular mechanisms of blood pressure-lowering properties of novel peptides reported in recent studies (2015-July 30, 2021) were discussed. In addition to common mechanisms such as the inhibition of angiotensin I-converting enzyme (ACE) and renin activities, recently recognized mechanisms through which bioactive peptides exert their antihypertensive properties including the induction of vasodilation via upregulation of cyclo-oxygenase (COX) and prostaglandin receptor and endothelial nitric oxide synthase expression and L-type Ca²⁺ channel blockade were presented. Similarly, emerging mechanisms of blood pressure-lowering by bioactive peptides such as modulation of inflammation (TNF-α, and other cytokines signaling), oxidative stress (Keap-1/Nrf2/ARE/HO-1 and related signaling pathways), PPAR-γ/caspase3/MAPK signaling pathways and inhibition of lipid accumulation were discussed. The review also highlighted factors that influence the antihypertensive properties of peptides such as method of hydrolysis (type and number of enzymes, and chemical used for hydrolysis, and microbial fermentation), and amino acid sequence and chain length of peptides.

Health-Promoting and Therapeutic Attributes of Milk-Derived Bioactive Peptides

Milk-derived bioactive peptides (BAPs) possess several potential attributes in terms of therapeutic capacity and their nutritional value. BAPs from milk proteins can be liberated by bacterial fermentation, in vitro enzymatic hydrolysis, food processing, and gastrointestinal digestion. Previous evidence suggested that milk protein-derived BAPs have numerous health-beneficial characteristics, including anti-cancerous activity, anti-microbial activity, anti-oxidative, anti-hypertensive, lipid-lowering, anti-diabetic, and anti-osteogenic. In this literature overview, we briefly discussed the production of milk protein-derived BAPs and their mechanisms of action. Milk protein-derived BAPs are gaining much interest worldwide due to their immense potential as health-promoting agents. These BAPs are now used to formulate products sold in the market, which reflects their safety as natural compounds. However, enhanced commercialization of milk protein-derived BAPs depends on knowledge of their particular functions/attributes and safety confirmation using human intervention trials. We have summarized the therapeutic potentials of these BAPs based on data from in vivo and in vitro studies.

Recent research progress of biologically active peptides

With the rapid development of molecular biology and biochemical technology, great progress has been made in the study of peptides. Peptides are easy to digest and absorb, with lowering of blood pressure and cholesterol, improving immunity, regulating hormones, antibacterial, and antiviral effects. Peptides also have physiological regulation and biological metabolism functions with applications in the fields of feed production and biomedical research. In the future, the research focus of bioactive peptides will focus on their efficient preparation and application. This article introduces a comprehensive review of the types, synthesis, functionalization, and bio-related applications of bioactive peptides. For this aim, we introduced in detail various biopeptides and then presented the production methods of bioactive peptides, such as enzymatic synthesis, microbial fermentation, chemical synthesis, and others. The applications of bioactive peptides for anticancers, immune therapy, antibacterial, and other applications have been introduced and discussed. And discussed the development prospects of biologically active peptides.

Flaxseed-derived peptide, IPPF, inhibits intestinal cholesterol absorption in Caco-2 cells and hepatic cholesterol synthesis in HepG2 cells

Flaxseed peptides reduced serum cholesterol levels in Sprague-Dawley rats fed with a high-cholesterol diet. However, the mechanism of this action remains unclear. Flaxseed-hydrolyzed proteins were separated through ultrafiltration. The fifth fraction (FP₅ , ≤ 1 kDa) had the highest cholesterol micelle solubility inhibition rate (CMSR) of 72.39% among the other fractions. Eleven peptides were identified from FP₅ . Ile-Pro-Pro-Phe (IPPF), which had the highest CMSR of 93.47%, was selected for further analyses. IPPF substantially reduced the cholesterol transported content in Caco-2 cells and the total cholesterol content in HepG2 cells. Moreover, IPPF modulated the protein levels of NCP1L1 and ABCG5/8 (cholesterol transporters) in Caco-2 cells and reduced the mRNA levels of Srebp-2 and Hmgcr (cholesterol synthesis enzymes) in HepG2 cells. IPPF inhibits cholesterol intestinal absorption by modulating the cholesterol transporters expression and reduces hepatic cholesterol synthesis by inhibiting the SREBP2-regulated mevalonate pathway. IPPF is a new food-derived cholesterol-lowering nutritional supplement. PRACTICAL APPLICATIONS: We isolated active peptides with cholesterol-lowering properties from flaxseed protein, a by-product of industrial oil production, which greatly improved the economic and medicinal value of flaxseed protein. According to our research, IPPF can be used as a new food-derived type of cholesterol intestinal absorption inhibitor to reduce dietary cholesterol absorption and cholesterol synthesis inhibitor (same pharmacological mechanism as statins). IPPF provide a nutritional therapy component for hypercholesterolemia and prevent atherosclerosis. Our research provides theoretical basis for development and utilization of new nutritional supplements and plant proteins.

Dairy bioactive proteins and peptides: a narrative review

Milk proteins are known for their high nutritional quality, based on their essential amino acid composition, and they exhibit a wide range of bioactivities, including satiety, antimicrobial, mineral-binding, and anti-lipidemic properties. Because of their unique water solubility, milk proteins are readily separated into casein and whey fractions, which can be further fractionated into many individual proteins, including alpha-S1- and alpha-S2-caseins, beta-casein, and kappa-casein, and the whey proteins alpha-lactalbumin, lactoferrin, beta-lactoglobulin, and glycomacropeptide. Many of these proteins have unique bioactivities. Further, over the past 30 years, peptides that are encrypted in the primary amino acid sequences of proteins and released along with amino acids during digestion are increasingly recognized as biologically active protein metabolites that may have beneficial effects on human health. This review examines the current state of the science on the contribution of dairy proteins and their unique peptides and amino acids to human health.

A comparative investigation into novel cholesterol esterase and pancreatic lipase inhibitory peptides from cow and camel casein hydrolysates generated upon enzymatic hydrolysis and in-vitro digestion

Cow (CwC) and camel casein (CaC) hydrolysates were generated using Alcalase™ (CwCA and CaCA) and Pronase-E (CwCP and CaCP) each for 3 and 6 h, and investigated for their potential to inhibit key lipid digesting enzymes i.e., pancreatic lipase (PL) and cholesteryl esterase (CE). Results revealed stronger PL and CE inhibition by CaC hydrolysates compared to CwC. Potent hydrolysates (CwCP-3 h and CaCA-6 h) upon simulated gastrointestinal digestion (SGID) showed significant improvement in inhibition of both PL and CE. However, both the SGID hydrolysates showed similar extent of PL and CE inhibition and were further sequenced for peptide identification. Peptides MMML, FDML, HLPGRG from CwC and AAGF, MSNYF, FLWPEYGAL from CaC hydrolysates were predicted to be most active PL inhibitory peptides. Peptide LP found in both CwC and CaC hydrolysates was predicted as active CE inhibitor. Thus, CwC and CaC could be potential source of peptides with promising CE and PL inhibitory properties.

New Nanocarrier System for Liposomes Coated with Lactobacillus acidophilus S-Layer Protein to Improve Leu-Gln-Pro-Glu Absorption through the Intestinal Epithelium

The present study describes the development of a novel liposome nanocarrier system. The liposome was coated with Lactobacillus acidophilus CICC 6074 S-layer protein (SLP) to improve the intestinal absorption of the cholesterol-lowering peptide Leu-Gln-Pro-Glu (LQPE). The SLP-coated liposomes were prepared and characterized with morphology, particle size, zeta potential, membrane stability, Fourier transform infrared spectroscopy, and dual-channel surface plasma resonance. The results showed that SLP could successfully self-assemble on liposomes. Then, LQPE liposomes and SLP-coated LQPE liposomes (SLP-L-LQPE) were prepared. SLP-L-LQPE not only showed better sustained release properties and gastrointestinal tolerance in vitro but also increased the retention time in mice intestine. Transepithelial transport experiment indicates that the transshipment of LQPE increased significantly after being embedded by liposomes and coated with SLP. The research provides a theoretical basis for the study of SLP-coated liposomes and a potential drug delivery system for improving the intestinal absorption of peptides.

New insights into the cholesterol esterase- and lipase-inhibiting potential of bioactive peptides from camel whey hydrolysates: Identification, characterization, and molecular interaction

Novel antihypercholesterolemic bioactive peptides (BAP) from peptic camel whey protein hydrolysates (CWPH) were generated at different time, temperature, and enzyme concentration (%). Hydrolysates showed higher pancreatic lipase- (PL; except 3 CWPH) and cholesterol esterase (CE)-inhibiting potential, as depicted by lower half-maximal inhibitory concentration values (IC₅₀ values) compared with nonhydrolyzed camel whey proteins (CWP). Peptide sequencing and in silico data depicted that most BAP from CWPH could bind active site of PL, whereas as only 3 peptides could bind the active site of CE. Based on higher number of reactive residues in the BAP and greater number of substrate binding sites, FCCLGPVPP was identified as a potential CE-inhibitory peptide, and PAGNFLPPVAAAPVM, MLPLMLPFTMGY, and LRFPL were identified as PL inhibitors. Molecular docking of selected peptides showed hydrophilic and hydrophobic interactions between peptides and target enzymes. Thus, peptides derived from CWPH warrant further investigation as potential candidates for adjunct therapy for hypercholesterolemia.

Effects of ultrasound-assisted sodium bisulfite pretreatment on the preparation of cholesterol-lowering peptide precursors from soybean protein

In order to take full advantage of the gastrointestinal digestive function, the effects of S-type ultrasound-assisted sodium bisulfite (UASB) pretreatment on the preparation of cholesterol-lowering peptide precursors derived from soybean protein were investigated and the structural characterizations of pretreated proteins were explored. UASB pretreatment with the operational mode of mono-frequency ultrasound at 28 kHz, ultrasonic power density of 200 W/L and ultrasonic time of 50 min exhibited the highest cholesterol-lowering activity (56.90%) of soybean protein hydrolysates (SPH) after simulated gastrointestinal digestion, which increased by 87.17% compared to the control. Under these conditions, the peptide content of SPH after simulated gastrointestinal digestion was not significantly different (p > 0.05) compared to the control. Further FTIR analysis showed that UASB pretreatment increased β-turn and β-sheet content and decreased α-helix and random coil content. The changes in the surface hydrophobicity and microstructures of soybean protein indicated that UASB pretreatment loosened soybean protein structure and exposed more hydrophobic groups. SDS-PAGE indicated that the restriction sites changed after UASB pretreatment. In conclusion, UASB pretreatment is an efficient method for the preparation of cholesterol-lowering peptide precursors.

Bioactive peptides in the management of lifestyle-related diseases: Current trends and future perspectives

Lifestyle-related diseases constitute a major concern in the twenty-first century, with millions dying worldwide each year due to chosen lifestyles and associated complications such as obesity, type 2 diabetes, hypertension, and hypercholesterolemia. Although synthetic drugs have been shown to be quite effective in the treatment of these conditions, safety of these compounds remains a concern. Natural alternatives to drugs include food-derived peptides are now being explored for the prevention and treatment of lifestyle-related complications. Peptides are fragments nascent in the primary protein sequences and could impart health benefits beyond basic nutritional advantages. Evidence suggests that by controlling adipocyte differentiation and lipase activities, bioactive peptides may be able to prevent obesity. Bioactive peptides act as agents against type 2 diabetes because of their ability to inhibit enzymatic activities of DPP-IV, α-amylase, and α-glucosidase. Moreover, bioactive peptides can act as competitive inhibitors of angiotensin-converting enzyme, thus eliciting an antihypertensive effect. Bioactive peptides may have a hypocholesterolemic effect by inhibiting cholesterol metabolism pathways and cholesterol synthesis. This review addresses current knowledge of the impact of food-derived bioactive peptides on lifestyle diseases. In addition, future insights on the clinical trials, allergenicity, cytotoxicity, gastrointestinal stability, and regulatory approvals have also been considered.