Abstract
The combination of probiotics with plant proteins presents a promising avenue for enhanced nutritional benefits, attracting considerable research interest. The interplay between plant proteins and probiotics holds substantial potential for improving the functionality of plant proteins. Fermented plant protein foods offer a unique combination of bioactive components and beneficial microorganisms, potentially enhancing gut health and combating chronic diseases. The use of various probiotic strains and plant protein sources allows for the development of innovative probiotic products with enhanced functionalities. However, the mechanisms and synergistic effects of these interactions require further investigation. This review explores the roles of plant proteins and probiotics in promoting health, elucidating regulatory mechanisms to showcase synergistic effects, and discussing challenges and future research prospects. Recognizing the multifaceted nature of interactions between plant proteins and probiotics, further research is needed for a comprehensive understanding of these mechanisms and their associated health benefits.
1. Introduction
Plant-based protein foods are gaining popularity as a viable alternative to animal proteins due to their low fat and calorie content, lactose-free composition, and other beneficial traits. This trend is particularly appealing to vegetarians and lactose-intolerant individuals, establishing plant-based proteins as rising stars in the plant nutrition market. The range of available plant proteins is expanding, encompassing sources such as cereals (oats, rice), pseudocereals (buckwheat, quinoa), legumes (soybeans, peas, mung beans, chickpeas), and nuts (almonds, walnuts), garnering significant interest from the industry.
The term "probiotic" originates from the Greek word "for life." Probiotics are living microorganisms that play a vital role in the fermentation of various food items, including vegetables, fruits, meats, dairy, and grain products. Their application enhances the nutritional value of these foods and offers numerous health benefits when consumed in adequate doses. The increasing global demand for preventive healthcare has fueled the growth of the probiotics market, which is expected to reach $119.28 billion by 2028. Commonly found in fermented foods or consumed as dietary supplements, probiotics are a valuable addition to a balanced diet. Probiotic fermentation in food preparation can alter the taste and composition of the final products. Specifically, the application of probiotics fermentation to different plant proteins can effectively break down anti-nutritional factors, thereby enhancing the overall nutritional value of the food. Probiotics can also improve the flavor and texture of plant-based beverages, mitigating undesirable taste and texture characteristics. Probiotic-fermented plant-based protein beverages offer advantages over conventional vegetable protein drinks in terms of vitamin content, improved nutrient absorption and bioactivity, product stability, and safety considerations.
Probiotics can effectively regulate pH levels to improve the solubility and digestibility of plant proteins. Through fermentation, probiotics can modify the structure and functionality of plant proteins, resulting in the production of bioactive substances such as vitamins, antioxidants, and antimicrobial peptides. Furthermore, probiotics facilitate protein absorption and utilization, addressing protein energy malnutrition. Additionally, probiotics alter the metabolic activity within the intestinal microbiota, maintaining a balance between protein degradation and synthesis.
The combination of plant proteins and probiotics exhibits synergistic effects, with plant proteins creating a favorable environment for probiotics growth and proliferation. Plant proteins, serving as a substrate for probiotic metabolism, support their growth and contribute to the synthesis of beneficial metabolites. This reciprocal interaction enhances the overall effectiveness of both plant proteins and probiotics in promoting gut health and facilitating nutrient absorption. The combination of protein and probiotics holds significant potential for promoting human health, including improving digestion, maintaining gut health, supporting the immune system, enhancing mental well-being, and improving nutrient absorption.
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The combination of multiple flavors, nutrition, food functionality, process refinement, and probiotics with plant proteins has become a focal point of current research. The fusion of plant proteins and probiotics can cater to various nutritional needs for human health while also delivering innovative taste and nutrition. These synergistic effects show significant potential in enhancing protein digestion and absorption thereby improving human health. The combination of specific probiotic strains and plant proteins is paving the way for advancing plant protein products. However, the mechanisms and challenges of these synergistic effects for health promotion necessitate further investigation. This review seeks to delve into the roles of promoting health through the interplay of plant proteins and probiotics. The regulatory mechanisms have been elucidated to demonstrate the synergistic effects, with a discussion on the challenges and prospects for future research.
Plant protein plays a crucial role in regulating the growth and metabolism of probiotics. Previous studies have shown that protein stimulates the synthesis of cytoplasmic proteins in probiotics, which in turn increases cell biomass and growth rate. Additionally, through fermentation, probiotics can alter the structure, modify functionality, facilitate bioactivity availability of plant proteins, regulate the absorption, and utilization of nutrients. Plant proteins are instrumental in improving the growth and proliferation of probiotics, stimulating the synthesis of cytoplasmic proteins in probiotics, supporting energy and metabolism, as well as maintaining the integrity of cell membranes. The combination of protein and probiotics demonstrates significant potential in promoting human health, including maintaining gut barrier, altering the metabolic activity within the gut microbiota, improving gut homeostasis, and enhancing immune response. By integrating plant proteins with probiotics, it becomes possible to meet diverse nutritional requirements while simultaneously achieving innovative taste and nutrition, thus offering promising applications.
Figure 1. The interactions between plant proteins and probiotics regulate nutrients metabolism and probiotic growth and proliferation.
2. Synergistic Effects of Plant Proteins and Probiotics
2.1. The promotion of probiotics growth and metabolism
Probiotics require a supply of nutrients for proliferation, and plant proteins act as an essential growth stimulant for probiotics. Protein promotes the synthesis of probiotic cytoplasmic proteins, thereby increasing cell biomass and growth rate. Amino acids and peptides in protein degradation products can be converted into energy and metabolites through metabolic pathways. The energy generated by this process can be used to maintain the basic metabolic needs of cells, as well as maintaining the integrity and stability of cell membranes. The amino acids sequence in protein can affect the activity of the enzyme inside the probiotics. The types and contents of amino acids in proteins have significant effects on the growth rate and biomass of probiotics.
In addition, probiotics can use protein degradation products as carbon and nitrogen sources for growth and metabolism. Carbon and nitrogen sources have important effects on the growth and metabolism of probiotics. Protein can serve as carbon source to provide the necessary carbon elements for probiotics growth and metabolic activities. At the same time, protein can also be used as a nitrogen source, in which amino acids can provide nitrogen elements required by probiotics to synthesize proteins such as cell structure and enzymes. Moreover, the peptides and oligopeptides can be produced by protein hydrolysis or self-hydrolysis are deemed to regulate the activity and stability of enzymes and thus promote the growth of probiotics. After the combination of probiotics and plant proteins, probiotics have a better survival chance, at the same time, play the physiological activity of probiotics and the growth-promoting function of prebiotics to produce health benefits to the host.
The effects of different types of proteins on probiotics are also different to some extent. Ding and Li found that when walnut oligopeptide was added at 2.0%, the number of viable bacteria reached 2.69 Ã 1010 CFU/mL, which increased the metabolic rate, promoted the proliferation of probiotics, and improved the activity of bacteria. Zhang et al. found that the peptides with small molecular weight from both soybean protein isolates and soybean peptides (PEPs) can be easier to effectively promote the growth of L. rhamnosus. It was also reported that the role of the soybean oligopeptide on JCM 1132 strain was manifested as promoting bacterial growth by increasing the content of tricarboxylic acid circulating intermediates, improving the metabolic capacity of L. acidophilus JCM 1132. In vitro simulated digestion tests confirmed that PEPs can act as a nitrogen source to promote probiotics growth and produce more lactic acid and acetic acid. These acids are derivatives of glucose metabolism by probiotics, demonstrating their efficacy in suppressing detrimental microorganisms.
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Probiotics fermentation also produces metabolites with antibacterial properties, such as organic acids, peptides. Studies have shown that after fermentation of soy milk with probiotic B. coagulans VHProbi C08, L. rhamnosus and L. helveticus K14, it has considerable antimicrobial capacity against Escherichia coli, Listeria monocytogenes, Salmonella enteritidis, Bacillus cereus and Staphylococcus aureus. The metabolites produced after the combination of proteins and probiotics can affect the growth and proliferation of probiotics and further promote the bioactive function of probiotics. has listed the recent studies to verify the influence of different plant proteins on probiotics growth and metabolites, promote the proliferation of probiotics. However, the specific effects can differ according to the probiotics type and multifactorial environmental. Further studies are required to fully understand how different plant proteins interact with probiotics, as well as their impact on gut health.
Table 1. The influence of different types of plant proteins on probiotics proliferation.
2.2. The enhancement of plant proteins functionality
2.2.1. The enhancement of plant proteins degradation
Proteolysis is triggered by cell envelope proteinase that breaks down proteins into polypeptides. Subsequently, dipeptides, tripeptides and oligopeptides may be taken up into the cells. In the metabolic pathway involved in metabolites of proteolysis, various enzymes play crucial roles, including cell envelope proteinase, peptidases, biosynthetic enzymes, dehydrogenase, aldolases, lyases, acyltransferases esterases, dehydrogenase, aminotransferases, decarboxylase, deiminases decarboxylase, dehydrogenase complex, and additional biosynthetic enzymes. Probiotics increase the production of protease and the enhanced activity of protease makes free amino acids a necessary factor for the proliferation of probiotics and also produces a variety of bioactive peptides. Furthermore, probiotics can induce the host to enhance the activity of digestive proteases and peptidases, as well as the release of exoenzymes involved in protein digestion. Peptidases such as PepN and PepXP play an essential part in releasing amino acids, cell growth, and biomass formation and are also involved in the production of precursors of flavor substances.
Figure 2. The roles of probiotics on proteolysis (A); the direct/indirect pathways of probiotics for gut microbiota-mediated proteolysis (B); and the effects of microbial metabolism on nutrient quality factors of plant food matrix (C).
FAA, free amino acids; BCAA, branch-chain amino acids; EAA, essential amino acids; IVPD, in vitro protein digestibility; IL, interleukin.
In the process of fermenting broad bean protein with the combination of Lactobacillus plantarum, Streptococcus thermophilus, and Lactobacillus acidophilus, more active protease will be produced, and plant proteins will be decomposed due to the synergistic effects between strains. After protein degradation and separation, small-molecule active polypeptides will be produced, and thus improve the nutritional quality and itself functional features. The fermentation uses proteases secreted by probiotics to hydrolyze proteins, optimize the texture, nutritional value, and bioactive substances of each plant source, and further promote the development of healthy fermented plant proteins.
In the process of fermenting plant proteins, probiotics can help to release and improve the active factors and metabolites and improve the utilization of plant proteins. Meanwhile, the probiotics will be in the lag or decline period and the secondary metabolites generated will decompose the plant proteins into small molecular peptides and free amino acids and then accumulate more amino acids and peptides. At the same time, the variations among the strains themselves will lead to diverse metabolism and utilization capacities of plant proteins. This phenomenon may be caused by varying microorganisms producing different enzymes in the growth and reproduction process and different positions or degrees of plant proteins being cut, resultin…
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The Gut Microbiome, Probiotics, and High-Protein Diets
The human body is home to trillions of microorganisms, both beneficial and harmful. A balanced gut microbiome, where beneficial bacteria outnumber the harmful ones, is crucial for overall health. Probiotics, live microorganisms that confer a health benefit when consumed in adequate amounts, can help maintain or restore this balance.
Probiotics: More Than Just Yogurt
Probiotics are found in fermented foods like yogurt, kefir, sauerkraut, and kimchi. They are also available as dietary supplements in the form of capsules, liquids, or powders. Not all yogurts contain probiotics, and for a yogurt to be considered probiotic, it must contain specific strains of bacteria.
How Probiotics Work
Probiotics contribute live, beneficial microbes to the gut, strengthening the existing microbial communities. They can help prevent and treat dysbiosis, an imbalance or deficit of beneficial microbes. Different types of probiotics have different functions, so consulting a healthcare provider about which probiotics might be best for specific needs is advisable.
Benefits of Probiotics
- Improved Digestion: Probiotics can aid in the digestion of food and alleviate digestive discomfort.
- Gut Health: They help maintain a healthy gut lining and promote a balanced gut microbiome.
- Immune System Support: A healthy gut microbiome can boost overall immunity.
- Mental Well-being: Emerging research suggests a link between gut health and mental health.
- Nutrient Absorption: Probiotics can enhance the absorption of essential nutrients, including amino acids.
Probiotics and High-Protein Diets: A Complex Relationship
High-protein diets have become increasingly popular for weight management and muscle building. However, the impact of high-protein diets on the gut microbiome is a subject of ongoing research.
The Potential Downsides of High-Protein Diets on Gut Health
Studies suggest that high protein intake without adequate dietary fiber can negatively affect the gut microbiome.
- Reduced Microbial Diversity: High-protein, low-fiber diets may decrease the diversity of gut bacteria.
- Lower Abundance of Beneficial Bacteria: These diets can reduce the number of beneficial bacteria, including those that produce short-chain fatty acids (SCFAs). SCFAs are important for gut health and overall well-being.
- Offsetting Exercise Benefits: High-protein, low-fiber diets may negate the positive effects of exercise on the gut microbiome.
The Role of Probiotics in Mitigating the Negative Effects
Probiotics may help counteract the negative effects of high-protein diets on the gut microbiome.
- Restoring Microbial Balance: Probiotics can introduce beneficial bacteria to the gut, helping to restore balance.
- Improving SCFA Production: Some probiotic strains can promote the production of SCFAs.
- Enhancing Amino Acid Absorption: Probiotics have been shown to increase the absorption of amino acids, which is particularly important for individuals following high-protein diets for muscle growth and repair.
Research Findings on Probiotics and High-Protein Diets
A study involving bodybuilders on extremely high-protein/low-carbohydrate diets found that probiotic supplementation did not lead to a positive effect on the gut microbial environment or SCFA concentrations. However, other studies have shown that when protein and dietary fiber intake meet recommended dietary allowances, gut microbial diversity and the relative abundance of beneficial bacteria are significantly different from those of sedentary subjects.
Considerations for Combining Probiotics and High-Protein Diets
- Adequate Fiber Intake: It is crucial to consume sufficient dietary fiber when following a high-protein diet. Fiber serves as a prebiotic, providing nourishment for beneficial gut bacteria.
- Probiotic Supplementation: Probiotic supplements may be beneficial, but it is important to choose strains that have proven benefits for gut health. Consulting with a healthcare professional or registered dietitian is recommended.
- Timing of Probiotic Intake: Taking probiotics on an empty stomach may help ensure that more probiotic bacteria reach the lower gut.
- Individualized Approach: The optimal approach to combining probiotics and high-protein diets may vary depending on individual factors such as gut microbiome composition, dietary habits, and exercise levels.
The Importance of a Balanced Diet
While probiotics and high-protein diets can offer potential benefits, it is essential to prioritize a balanced and varied diet rich in fruits, vegetables, whole grains, and lean protein sources. A healthy diet, combined with regular exercise, is the foundation for optimal gut health and overall well-being.