Exploring the significance of resistant starch in ready-to-eat meals for enhanced functioning of gut microbiota: a comprehensive review

Abstract

The increasing interest in functional foods has highlighted the potential advantages of resistant starch (RS), a dietary fiber with prebiotic characteristics, in improving gut health. This review investigates the importance of integrating RS into ready-to-eat (RTE) meals, analysing its impact on gut flora and enhancing overall digestive health. Also, assesses the influence of RS-enriched RTE meals on the diversity and activity of gut microbiota, emphasizing the production of short-chain fatty acids (SCFAs) and other significant metabolites through a thorough examination of contemporary literature and emerging research. Furthermore, emphasizes the challenges and prospects of integrating RS into RTE food products while maintaining taste, texture, and consumer acceptability. The findings indicate that incorporating dietary RS into ready-to-eat meals may serve as an effective approach to promoting gut microbiota equilibrium, increasing digestive health, and aiding in the prevention of chronic disorders associated with gut dysbiosis.

Introduction

The association of human health with the intestine has been long acknowledged as Hippocrates said, “Death sits in the bowls” in 400 B.C. (Afzaal et al., 2022). Recent studies, encompassing epidemiological, physiological, omics-based, cellular, and animal research, suggest that microbial communities, particularly the intestinal microbiota, significantly influence human health and disease risk. These microorganisms, collectively referred to as the microbiota, is a complex community of microorganisms that live in the digestive tracts of humans and animals, including insects. The human body is colonized by a diversity of microbiota that represents all the microorganisms like bacteria, viruses, fungi, archaea, protozoans and unicellular eukaryotes that colonize skin, mouth, respiratory system, gastro-enteric tube, and vagina, although over 70% microbiota lives in the gastrointestinal (GI) tract (Tagliasco et al., 2025). This complex organ is occupied by more than 100 trillion microbes, representing as many as 5000 different species, and weighing approximately 2 kg and it is crucial the association between richness and diversity of the microbial community and health (Ruan et al., 2020).

Most of the human gut microbiota is made up of five primary phyla: Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Verrucomicrobia. The most abundant among them are Firmicutes and Bacteroidetes, which collectively contribute to approximately 90% of the gut microbiota (Zhang, 2022). Specifically, Firmicutes, Lactobacillus, Clostridium, and Ruminococcus are typical genera that make up 64% of the microbial population. As the second most common phylum, Bacteroidetes reflects around 23%, of which most are genera Bacteroides and Prevotella. Actinobacteria and Verrucomicrobia are comparatively rare parts, contributing about 3 and 2%, respectively (Van Treuren and Dodd, 2020). These phyla have an enormous diversity within them; Firmicutes can be further divided into classes such as Clostridia, Bacilli, Erysipelotrichi and Negativicutes and families of Lachnospiraceae and Ruminococcaceae. It is believed that the balance between the number of Bacteroides and Firmicutes is essential for human health and plays a role in metabolic processes and may be involved in obesity and inflammatory disease, especially (Adak and Khan, 2019; Jethwani and Grover, 2019). Both intestinal and systemic actions of the gut microbiota are necessary to ensure the maintenance of body homeostasis by influencing both intestinal and systemic physiology, including metabolism, barrier integrity, inflammation, and hematopoiesis. It has been recognized as a “vital organ” due to its extensive communication network with other organs via neural, endocrine, humoral, immune, and metabolic pathways. Alterations in the microbial community not only lead to gut-related disorders but also contribute to diseases affecting other organs. However, the precise mechanisms underlying these gut-organ interactions remain incompletely understood (Ahlawat et al., 2021).

The composition of the gut microbiome exhibits significant inter-individual variability influenced by various factors including genetics, age, mode of delivery (vaginal or cesarean), infant feeding methods (breast milk vs. formula), medication (notably antibiotics), geographical region, and dietary habits (Rinninella et al., 2019; Sánchez-Tapia et al., 2019). The gut microbiota, primarily residing in the intestines, plays crucial roles in immune system training, food digestion, and regulation of gut endocrine functions, neurological signalling, drug metabolism, toxin elimination, and the production of beneficial compounds. Factors such as host genetics, diet, age, and antibiotic use can alter gut microbiota composition and function, leading to variations among individuals. Additionally, dietary habits, cultural practices, exercise, stress levels, as well as and environmental influence influences continuously shape the microbial landscape (Fan and Pedersen, 2021). The link between gut microbiota and diet is intricate, extensive, and reciprocal. However, there is a corollary to this assertion: the gut microbiota’s makeup can influence the host’s absorption and metabolism of nutrients, potentially playing a crucial role in host physiology (Yang et al., 2020). On the contrary, the composition and functionality of the microbiota can be modulated by nutrients, bioactive compounds, some foods and dietary patterns and can have either beneficial or harmful effects on health. Therefore, diet adjustment has been proposed as a therapeutic strategy for regrouping the gut microbiota and counteracting dysbiosis related to nutrition disease (Rinninella et al., 2019; Sánchez-Tapia et al., 2019).

Dietary components, and especially fiber, provide essential driving forces determining the gut microbiota composition and functionality, a large and at the same time highly diverse community of microorganisms living in the GI tract. Thanks to their metabolic versatility, those microorganisms can digest dietary nutrients into products that ensure that beneficial metabolites will make a large impact on the host’s health, including metabolism, immune function and gut integrity. Considering dietary components, fiber is the gross modulus of gut microbiota because it is a major substrate of microbial fermentation in the colon. Indigestible carbohydrates are fermented by gut microbes into SCFAs such as acetate, propionate butyrate, and fibre. These SCFAs are required for human health. However, butyrate is an important part of human health as it is utilized as the primary energy source for colonic epithelial cells (colonocytes) and takes part in several physical processes including autoimmunity (Koh and Bäckhed, 2020). It encourages epithelial cell proliferation and differentiation and is also a potent anti-inflammatory. Moreover, butyrate is anti-carcinogenic by inducing apoptosis in colon cancer cells and modifying the transcriptional expression of genes through the inhibition of histone deacetylase (Afzaal et al., 2022; Wang et al., 2019).

The liver is responsible for the gluconeogenesis of propionate, and acetate is a co-factor for bacterial growth, as well as supporting other metabolic processes, such as lipogenesis (Ramos and Martín, 2021; Rowland et al., 2018). Dietary carbohydrate composition affects the dynamics of gut microbiota with simple carbohydrates (such as mono- and disaccharides) being often related to the growth of opportunistic pathogens and decrease in SCFA-producing bacteria (Seo et al., 2020). On the contrary, complex carbohydrates (microbiota accessible carbohydrates; MAC), serve as a substrate for microbial fermentation to increase SCFA levels and support health-promoting bacteria such as Akkermansia, Bacteroides, Bifidobacterium, Clostridium, Lactobacillus, Prevotella, Ruminococcus and Faecalibacterium (Yang et al., 2020). Without these bacteria humans could suffer from a variety of metabolic and immune-related diseases as well as inflammation.

RS is one type of the various types of MAC, which has gained interest due to its special properties and its huge health benefits. RS is a type of carbohydrate that has not been digested in the small intestine and thus reaches the colon undigested where the gut microbes ferment it. In this case, SCFAs and other metabolites generated in this process have numerous health benefits, such as improving microbial diversity and enhancing gut barrier function (Wang et al., 2025a). RS is prebiotic and selectively spurs the growth of beneficial gut bacteria to improve microbiomes. Faecalibacterium prausnitzii and other SCFA-producing microbes are important to support its proliferation as well as gut health (Rauf et al., 2022). RS has been proven to reduce inflammation, improve immune response and prevent the occurrence of metabolic diseases like obesity and type 2 diabetes. Moreover, it plays an important role in metabolic health because besides improving insulin sensitivity, RS also helps to regulate lipid metabolism (Wang et al., 2019).

Similar patterns are seen in diet and gut microbiota, as well as the relationships between those two, though diet and no single components can affect microbiota. Our diets high in sugar and fat are Western-style diets, which interfere with the natural balance of the microbes and decrease the production of beneficial SCFAs. Mediterranean and vegetarian or vegan diets, which are rich in fiber and microbiota-accessible carbohydrates, stimulate microbial diversity and the growth of health-associated bacteria in contrast. The composition and function of gut microbiota are influenced particularly by fiber. This fermentation is important for its contribution to gut integrity, anti-inflammatory properties and metabolic health, and it particularly hinges on fiber fermentation, especially RS, to SCFAs. RS and such fiber-rich foods can be incorporated into the diet as a promising way to provision a healthy microbiome and overall well-being.

Understanding resistant starch

In 1992, the Food and Agriculture Organization (FAO) of the United Nations and the European starch Englyst Resistance Collaborative Group suggested RS described as not digested and absorbed in the small intestine but it can ferment or partially formation of starch and starch degradation products in large intestine (Cerqueira et al., 2020).

Type of resistant starch

Within the categories, there is some variation in the RS content of food, determined by the nature and composition of the food, food processing methods, storage conditions and consumption practices. RS is classified into five main types, each reflecting these influences. RS was first classified into three categories (RS1, RS2, and RS3), but the classification increased with the addition of RS4 and RS5 in later years (Zhou et al., 2024). Generally, RS is divided into five types, depending on the different resistance mechanisms to digestion in the human body, and its character and occurrence as shown in Table 1.

Table 1.

Overview of resistant starch types and their digestive characteristics

Types of resistant starch	Examples of occurrence	Character	Resistance minimized by	Digestion in small intestine	References
RS1-Physically inaccessible	Whole or partly milled grains and seeds, Grains and legumes	Surrounded by protein matrix and cytoplasmic material	Milling, chewing	Slow rate, partial degree, totally digested if properly milled	DeMartino and Cockburn (2020)
RS2-Resistant granules	High amylose corn starch, raw potatoes, green bananas, some legumes	Dense ungelatinized starch granules which inhibit enzyme access and activity	Food processing and cooking	Very slow rate, little degree, totally digested when freshly cooked	Rauf et al. (2022)
RS3-Retrograded	Cooked and cooled potatoes, rice and pasta	A starch structure formed by retrogradation after gelatinization	Processing conditions	Slow rate, partial degree, reversible digestion, digestibility improved by reheating	Koh and Bäckhed (2020)
RS4-Chemically modified	Etherised, esterified or cross bonded starches (used in processed foods). Some drinks, foods contained modified starches have been used (certain breads and cakes)	Chemically modified starch, via chemical cross-linking of starch by the addition of esters and ether groups	Less susceptible to digestibility in vitro	A result of Chemical modification, can resist hydrolysis	Zhu et al. (2020)
RS5- Amylose–lipid complexes	Amyloid-stearic acid complex	Starch-lipid complexes, insoluble in water, and has thermal stability properties, which makes it difficult to combine with amylase	Not susceptible To hydrolysis by α- amylase	Can resist digestion	Kraithong et al. (2022)

RS1 (physically inaccessible starch)

Type 1 resistant starch (RS1) is the starch found within plant cells that have undamaged cell walls, such as in not fully ground cereal grains. It is resistant to amylolytic enzymes due to the absence of enzymes in the gastrointestinal tract capable of breaking down cellulose, hemicelluloses, lignins, and other components of plant cell walls. As a result, this starch, along with fragments of plant tissue, passes through the small intestine without being digested (Farooq and Yu, 2024). RS1, commonly derived from whole grains and legumes, is encased in a protein matrix and cytoplasmic material, forming a protective barrier that prevents enzymes from accessing and hydrolyzing the starch (Kraithong et al., 2022; Sánchez-Zapata et al., 2011). However, proper grinding and crushing can make this starch digestible in the small intestine. Therefore, the level of grinding, as well as human chewing or food processing methods, can influence the RS1 content in food. The degree of milling is a key factor in determining the digestibility of RS1. Starch exists primarily in two forms: amylose and amylopectin (Ai and Jane, 2024). The characteristic relatively small, linear polymer and comprised of 100–10,000 glucose monomer units in an α-(1 → 4) glycosidic bond, amylose. Amylopectin is, however, a much larger polymer, having on the order of 10,000 to 100,000 monomer units, with many α (1 → 6) branching points. The structure of the starch in the granule’s crystalline regions is influenced by the arrangement of these branches in linear regions. The amorphous portions of the starch granule contain a large amount of amylose (Zhang et al., 2024). On the other hand, commercial starches normally have 70–80% amylopectin and thus can easily gelatinize when heat and water are mixed. Yet, some latest maize cultivars have more than 80% amylose content. Additionally, recent studies indicate that artificially isolated RS1 can change the gut microbiota composition. The abundance of beneficial genera Clostridium and Butyricoccus, and potential harmful genera Bacteroides, Lactobacillus, Oscillospira and Ruminococcus has been found to increase and decrease, respectively, following the addition of dialysate. Downregulated bacteria were positively correlated with inflammation, and imbalances in blood glucose metabolism, while Clostridium was negatively correlated with these conditions (Zhu et al., 2020). This result implies not only that RS1 generally affects starch digestibility, but also that it affects the gut microbiota in a way that modifies to modulate metabolic health. RS1 has some notable health benefits; It helps to keep the digestive system healthy by promoting regular bowel movements and increasing the bulk of stool caused by its fibrous properties. Also, RS1 helps regulate blood sugar levels by slowing the absorption of carbohydrates, so if you are diabetic or insulin-sensitive, this could be very helpful for you. Additionally, as RS1 reaches the large intestine intact, it is the substrate for fermentation by gut microbiota which produces SCFAs that support gut health and could reduce inflammation. Therefore, RS1 can be considered a functional food ingredient that can boost gut health and metabolic functionality.

RS2 (raw starch granules)

One of the most popular forms of RS, raw starch granules (RS2) is present in various foods like high amylose of corn starch, raw potatoes, green bananas and legumes (Li et al., 2019). RS2 has a unique structure and crystal habit, non-gelatinized compact starch granules inhibit enzyme accessibility and functional properties. This property also is similar to resistance to digestion seen for high amylose corn starch and immature potato starch. RS2 starch crystals are characterized by three kinds of crystal types (A-type, B-type, and C-type) from their X-ray diffraction pattern. Most A-type crystals occur in cereal crop seeds, B-type crystals in plant tubers and the seeds of crops having a high content of straight chain starch and C-type crystals are found in legume seeds and yam rhizomes (Bangar et al., 2024). RS2 and RS3 have a factor in the characteristics are their amylose to amylopectin ratios. They have structural properties that make it possible to heat their gelatinization temperature above the normal temperature of regular corn starch. However, when gelatinized the high amylose content results in rapid retrogradation of starch paste. When the starch paste cools, the linear amylose chains retrograde forming insoluble crystallites that do not resist enzymatic hydrolysis (Jojo et al., 2024). After cooling the starch, this produces small amylose domains interspaced with amylopectin regions (Wei et al., 2025). Because studies have shown RS2 starch from rice has a slower fermentation rate during in vitro digestion, there is a higher concentration of butyric acid (67.85%) and increased abundant Prevotellaceae, which are beneficial for SCFA synthesis. This also raised Faecalibacterium abundance and lowered potentially harmful bacteria like Megamonus and Proteobacteria, among other changes, helping to maintain gut balance (Li et al., 2021). Research discovered that consumption of unmodified potato starch in the diets of healthy adults further increased faecal levels of butyrate, while also encouraging, as a percentage of the total bacterial community, beneficial bacterial like Bifidobacterium adolescentis and Ruminococcus bromii. SCFAs from RS2-enriched diets reduced overgrowth of Lactobacillus reuteri in innate inflammatory conditions resulting in improved health outcomes in lupus models (Zegarra-Ruiz et al., 2019). High amylose RS2 increased Ruminococcaceae_UCG-005 members up to 2.11-fold, when 40 g of high amylose RS2 was consumed in the daily diet of healthy individuals (Zhang et al., 2013). RS2 is considered more than just for its effect on gut microbiota. Satiation (the opposite of satiety) would make you feel full quickly after a meal, unimportant calories may be consumed before satiating your needs. RS2 also promotes satiety, which can support weight management by increasing feelings of fullness after meals. RS1 and RS2 work similarly to other things that help moderate blood sugar levels by slowing down the digestion and absorption of carbs. In addition, RS2 is a prebiotic that stimulates the establishment of beneficial gut bacteria and promotes the health of the gut by increasing the levels of SCFAs produced during fermentation. These collective effects make it possible to support both gut microbiome balance and metabolic health with RS2 giving numerous health benefits.

RS3 (retrograded starch)

Retrograded starch (RS3), or retrograded starch, occurs when starches from cooked and then cooled foods (i.e. potatoes, rice and pasta) retrograde. If starch is first heated to gelatinize, then cooled down to have the starch crystallize into a more ordered structure (RS3). Degradation of RS3 may occur with processes of acidic or enzymatic hydrolysis leading to the formation of smaller molecules that increase the crystallinity of RS3. Furthermore, various processing treatments including ultrasonic treatment, extrusion, autoclaving, microwave cooking and heat-moisture processing are applied to RS3 to generate various structural characteristics (Ma et al., 2020). Processed legumes have a high RS3 content and the digestibility of legume starch is, therefore, lower than that of grain starch (Obadi and Xu, 2024). Moist heat processing forms physically modified starches or RS3, commonly referred to, i.e., retrograded starch, or recrystallized amylose. This process occurs during the cooking of gelatinized starch and in starchy foods that are stored at lower or room temperatures. RS3 is particularly notable for its thermostability and is used as an ingredient in a wide range of conventional food products. Examples of RS3-rich foods include cooked and cooled potatoes and corn flakes.

RS3 is a significant form of RS from a nutritional perspective due to its higher water-holding ability than granular starch (Si et al., 2024). During the storage of gelatinized starch at low temperatures, the amylose molecules realign and aggregate, forming a thermostable B-type crystalline structure. The retrogradation of amylose makes the α-1,4 glucosidic linkages less accessible to amylase, contributing to the resistance of RS3. These crystalline aggregates are so stable that they can only be rehydrated at temperatures above 150 °C. The formation of RS3 is influenced by both the storage temperature and duration. Lower storage temperatures promote more RS3 formation, as compared to higher temperatures (Roman and Martinez, 2019). Starch crystallinity is also temperature-dependent; at low temperatures, B-type crystallinity is formed, whereas at higher temperatures, A-type crystallinity predominates.

Starch gels typically contain both amorphous and crystalline fractions, with the crystalline portion being resistant to amylolytic enzymes. Amylose–lipid complexes can reduce RS3 formation, and although amylopectin may also participate in the crystallization process, its structures are less thermostable and crystallize more slowly than amylose. Amylopectin-based crystallization can be rehydrated at temperatures between 55–70 °C. The production of RS3 is further determined by the botanical source of starch, amylose content, and the specific processing methods used (Farooq and Dhital, 2024). The retrogradation of amylopectin can be accelerated with repeated cycles of heating and cooling. RS3 provides several health benefits, much like other forms of RS. It aids in glycaemic control by slowing carbohydrate digestion and absorption, which helps stabilize blood sugar levels after meals. Additionally, by increasing sensations of fullness, RS3 encourages satiety, which can help with weight management. By promoting fermentation in the gut microbiota and the consequent synthesis of SCFAs, RS3 also contributes significantly to gut health. Thus, because of these health advantages, RS3 plays a crucial role in preserving general metabolic and intestinal health.

RS4 (chemically modified starch)

Chemically modified starch or RS4 is a group of starches that have been chemically modified by processes like etherization, esterification or cross-linking. These modifications block enzyme access to the molecules of starch and thereby to its hydrolytic enzymes and hence its degradation (Kim et al., 2008). RS4 (retrofitted RS) has unique properties, with varying degrees of digestibility depending on the degree of substitution. For instance, acetylated and hydroxypropylated starches show higher resistance and the resistance increases with the degree of substitution (Wepner et al., 1999). Native starches are particularly susceptible to enzyme hydrolysis, while its derivatives, such as hydroxypropyl distarch phosphate and acetylated distarch phosphate, are less susceptible (Östergård et al., 1988). Chemical modification of starch involves conversion, substitution or cross-linking. The modification of starch granules in terms of changes in structure, composition, and properties results in a greater resistance of the starch to amylolytic enzymes. For example, the natural properties of starch are modified by the introduction of ester and ether groups through chemical crosslinking. Such modifications may affect other starch properties, such as the gelatinization temperature, thermal viscosity, freeze–thaw stability, gelation strength, film formation, transparency, and enzymatic stability (Hoover and Zhou, 2003). Acetylated starches, starch graft copolymers, crosslinked starches, thermally modified starch, phosphorylated starch, and hydroxypropyl starch are all considered types of RS4.

Genetic modification of the starch molecules can also take place before planting as they are modified to make the starch more appropriate for particular applications. The chemical modification of RS4 can have different effects on its content in a food product, depending on the degree of modification, that is, the substitution level and the method applied (Wurzburg, 1986). For example, acetylated starches have typically less than a 2.5% substitution level. Nevertheless, the content of RS in processed foods may also be affected by such factors as particle size. Chewless starch particles, which are larger, may not be digested as quickly as smaller-sized particles and, hence remain resistant to digestion longer (Lewis and Heaton, 1999). The difficulties in quantifying the physiological influences over RS are RS, individual chewing and transit time, which can affect the starch’s effective RS content. Hence, RS4 is sometimes referred to as its ‘physiological’ and ‘chemical’ forms, which are concerned with the behavior of RS4 in the body and the values, which are determined by chemical analysis (Annison and Topping, 1994). For example, RS4 usually takes place in processed foods as a thickening aid or stabilizer and presents numerous health benefits. Like all other RS, RS4 contains a lower calorie value because it is not digested and is useful for blood sugar control. In addition, RS4 functions as a prebiotic increasing the development of healthy gut bacteria and encouraging intestinal health.

RS5 (amylose–lipid complexes)

RS Type 5 (RS5) also called amylose lipid complex (ALC) represents one specific form of RS that is produced by noncovalent interaction among amylose and lipid. When lipids are present in starch gelatinization, the quality of amylose structure undergoes a complex transformation. In the small intestine, the formation of stable complexes between lipid molecules and the helical form of amylose, resistant to enzymatic hydrolysis, results from the change of the amylose conformation from a random coil to a helical form. Multiple factors influence the formation of RS5, including the type of lipid used in the formation of the complex, the conditions of formation, and the molecular structure of amylose itself. However, complexes rich in long-chain fatty acids such as oleic acid give rise to complexes particularly stable and resistant, since size and structure can fit into amylose helical configuration. RS5 is the term for long chains of amylose and amylopectin that interact with fatty acids of fatty alcohols (Castro-Campos et al., 2024). Among RS5’s many properties, it is insoluble in water and thermally stable, which means that it is resistant to digestion by amylase. It is because the configuration of the starch lipid complex presents amylopectin molecules interwoven with it to cause it to be less expanded, thus making it harder for amylase to access and hydrolyze the starch. Therefore, RS5 is more resistant to digestive enzymes than amylose. To provide an example, an amyloid stearic acid complex can inhibit starch granule expansion by covering with stearic acid on the surface of the starch granules, and greatly increasing the resistance to enzyme RS5 (Zhong et al., 2024). The small intestine does not digest or absorb all types of RS; rather, their digestion differs in terms of rates, structures, and physiological features. As a result of these variances, functional characteristics can vary depending on the type, source, and quantity ingested.

RS5 has many health benefits. RS5 is resistant to digestion and is not digested until it reaches the colon, where it undergoes fermentation by gut microbiota. Fermentation produces SCFAs, which promote gut health and normalize metabolic pathways. Another potential effect of RS5 gut microbiota throughout fermentation is glycemic control, by slowing down both carbohydrate digestion and absorption, and reducing carbohydrate-induced acute fluctuations of blood glucose levels. Furthermore, this dietary fibre content offers a host of advantages to people with diabetes or anybody else looking to maintain balanced energy compatibility throughout the day (Raigond et al., 2014). In addition, RS5 promotes satiety, potentially supporting weight management by improving postprandial satiety. Functional characteristics of amylose–lipid complexes are also employed as processing attributes that enhance food product production. For example, RS5 can improve texture and stability in starchy foods by reducing dispersion during cooking and limiting retrogradation the process responsible for staleness in cooked starches. ALCs can therefore have applicable uses in other food formulations as well, such as baked goods and pasta, where texture is a key property to maintain and shelf life is an important aspect to optimize through extended freshness at storage. Additionally, researchers are developing novel methods for RS5 formation via regulated processing techniques, both to maintain its health-promoting attributes and improve its functional characteristics towards food applications.

Digestive process of RS

RS takes a complicated journey through the human body starting in the mouth, traveling through the gastrointestinal tract, and finishing with fermentation in the colon. RS is defined as starch that escapes from gastrointestinal digestion and reaches the colon and is then fermented with gut microbiota (Li and Hu, 2023). This sets it apart from common starches, which can be hydrolyzed into glucose and be absorbed in a relatively large way in the small intestine. RS can also be consumed in foods such as some starchy vegetables, legumes and whole grains: something known as dietary RS. RS is not digested by proximal small intestinal enzymes such as amylase and is instead fermented in the distal gut, in contrast to digestible starch, which is quickly hydrolyzed by digestive enzymes. This physical barrier prevents the access of enzymes, enabling RS to outwit the digestive tract in the upper gastrointestinal tract (Zhang et al., 2022).

RS in the small intestine

The five predominant forms of RS resist degradation by digestive enzymes in the small intestine, leading them to be transported into the large intestine. Pancreatic enzymes including α-amylase that further hydrolyze starch into amylose are found in the small intestine (Tuncil et al., 2017). Lipase acts on lipids, generating free fatty acids (FFAs). In a neutral environment, amylose and FFAs may form starch-lipid complexes. However, this complex formation competes with the processes that break down starch into monosaccharides and FFAs into micelles. While the formation of starch-lipid complexes in the small intestine remains speculative, animal studies have shown that starch and fat in feed can form starch-lipid complexes, which resist full digestion and absorption. This resistance to enzymatic breakdown leads to the incomplete utilization of energy, with FFAs being excreted in the stool. Studies also suggest that starch-lipid-protein complexes are more resistant to amylase than starch-lipid complexes, indicating that combinations of multiple compounds may increase resistance to enzymatic hydrolysis (Ze et al., 2013). Despite these interactions, RS largely remains undigested in the small intestine. The resistance can be attributed to several factors, including the crystalline structure of certain types of RS (such as RS2) and the protective matrix provided by cell walls in whole foods (as seen with RS1). As a result, RS does not contribute to a rapid rise in blood glucose levels, making it beneficial for glycemic control. After passing through the small intestine, RS Resistant starch continues into the large intestine, where it undergoes further fermentation.

Digestion in the large intestine

Once RS reaches the large intestine, it serves as a substrate for fermentation by gut microbiota. During this fermentation process, SCFAs such as acetate, butyrate, and propionate are produced, playing crucial roles in maintaining gut health. Butyrate is particularly significant, as it has anti-inflammatory properties and serves as a key energy source for colon cells (colonocytes). Besides SCFAs, gaseous fermentation products such as hydrogen, methane and carbon dioxide are also yielded (Crost et al., 2018). The particular chicken-ness or cow-ness of the RS-3 in a diet translates to the kind and quantity of SCFAs produced in the intestines, as gut microbes tend to be more or less sensitive to each form of RS. Inter-species interaction on RS degradation plays an essential role between the types of RS, where RS is directly degraded to SCFAs by some of the most important bacteria involved in RS degradation, such as Ruminococcus bromii and Bifidobacterium adolescentis, these bacteria are known to also take part in cross-feeding (Larsbrink et al., 2014). This mechanism enables the RS fermentation initial metabolites, to be utilized as nutrients for other beneficial bacteria in the gut. RS further stimulates the shift in gut microbiota composition, leading to the proliferation of beneficial bacteria and suppression of pathogenic bacteria. As a result, microorganisms undergo a rebalancing towards particular roles that offer health benefits like improved metabolic health and a lower risk of colorectal cancer (Belenguer et al., 2006). Among microorganisms, butyrate, as one of the most abundant generated SCFAs, has gained attention with its constipation function on colon homeostasis and its involvement in mediating energy metabolism and inflammation. Moreover, RS increases satiety; an important parameter to control weight (Cockburn and Koropatkin, 2016). This is because it makes people feel fuller, and are eating less food at a time, something that is great for those that are looking to get their metabolic health back on track or lose some weight.

Hypothesized digestion of starch-lipid complexes

It has been shown that the starch–lipid complexes (starch–oleic acid complexes such as rice starch–oleic acid) exhibit unique digestion characteristics different to other types of RS so that many animal studies have proven that these RS subtypes activate butyrate-producing bacteria in the intestine (Zheng et al., 2020). It is assumed that these complexes are fermented in the large intestines, releasing FFAs that, because of the anaerobic conditions, may be hydrogenated to saturated fatty acids (Drochner and Meyer, 1991). This hypothesis needs to be confirmed by more studies.

Gut microbiome and RS fermentation

The fermentation of RS occurs mainly in the gut microbiome. Intestinal microbiota ferments indigestible carbohydrates such as RS, resulting in the generation of beneficial metabolites, particularly SCFAs, in the colon (Hamer et al., 2008). In particular, butyrate is important for colon health as well as preventing inflammation. SCFAs provide a modulating effect at gut pH levels which promotes the growth of beneficial bacteria and prevents pathogens (Canani et al., 2011). The RS fermentation is more selective, and some bacteria (especially from the Bacteroidetes and Firmicutes phyla) are better at fermenting RS than others (Walker et al., 2011). As a result, regular RS ingestion encourages the colonisation of RS-fermenting bacteria, which increases the production of SCFAs that are good for gut health. In summary, RS fermentation in the large intestine increases colon health, lowers inflammation, and encourages the growth of beneficial bacteria all of which can have a variety of positive health effects.

Mechanisms of action

First of all, the role of RS in the interaction of the gut microbiota to produce SCFAs is very important but complicated for human health. In contrast to digestible starches, RS is not digested in the small intestine and reaches the colon, where it is a substrate for fermentation by the resident microbial community. During this fermentation process, SCFAs, especially butyrate, propionate, and acetate, as well as gases, including hydrogen, methane, and carbon dioxide are produced. (Hamer et al., 2008). The beneficial effects of RS consumption on gut microbiota and metabolic health are depicted in Fig. 1.

Fig. 1.

An overview of RS consumption impacts the human gut

RS arrival in the colon

RS’s resistance to digestion in the small intestine is due to its molecular structure, which can be categorized into different types (Birt et al., 2013):

• RS1: Starch physically trapped within plant cell walls (e.g., whole grains, seeds, legumes).

• RS2: Native granular starch in uncooked foods with a high amylose content (e.g., raw potatoes, green bananas, high-amylose maize).

• RS3: Retrograded starch formed when cooked starchy foods are cooled (e.g., cooked and cooled potatoes, bread, and rice).

• RS4: Chemically modified starch (not naturally occurring).

This structural resistance allows RS to bypass the enzymatic action of amylases in the small intestine and proceed to the colon, where the majority of the gut microbiota resides.

Microbial fermentation

The colon hosts a dense and diverse microbial ecosystem, comprising bacteria, archaea, fungi, and viruses. This community plays a vital role in fermenting undigested dietary components, including RS. Specific bacterial groups are particularly adept at RS fermentation (Walker et al., 2011):

• Bacteroidetes (especially Bacteroides): This phylum is known for its capacity to metabolize a wide range of complex carbohydrates. Bacteroides species have enzymes capable of digesting RS to smaller sugars, which are then fermented to SCFAs (Ze et al., 2013). These bacteria play a role in various other gut health factors such as gut barrier integrity, immune regulation, and vitamin synthesis.

• Firmicutes (notably Ruminococcus): The bacterium Ruminococcus bromii, which is recognized as a keystone species of RS fermentation, has a very high efficiency for initiating RS degradation (Qin et al., 2010). This first degradation allows RS to be more readily utilized for fermentation by other taxa of microbes. In RS-rich diet consumed individuals, abundant Ruminococcus is commonly correlated with gut health improvement.

• Actinobacteria (notably Bifidobacterium): These bacteria are popular probiotics and have many health effects. They also ferment RS to produce SCFAs, contributing to a lower gut pH, which inhibits the growth of some pathogenic bacteria (Turroni et al., 2012). RS has documented bifidogenic effects, increasing Bifidobacterium counts in the gut.

• Archaea (especially Methanobrevibacter smithii): This methanogenic archaeon plays an indirect but crucial role by consuming hydrogen (H₂) produced during fermentation and converting it to methane (Samuel and Gordon, 2006). This hydrogen removal prevents its accumulation, which can inhibit the fermentation process, thus maintaining a more favorable environment for other fermenters.

Production of SCFAs

The anaerobic fermentation of RS by these microbial groups leads to the production of SCFAs, primarily:

• Butyrate: This is the primary energy source for colonocytes (the cells lining the colon) and is crucial for maintaining colonic health (Canani et al., 2011). Butyrate exhibits anti-inflammatory properties, strengthens the colonic defense barrier, and may reduce the risk of colon cancer.

• Propionate: This SCFA is mainly transported to the liver, where it influences glucose metabolism and cholesterol synthesis.

• Acetate: This is the most abundant SCFA produced in the colon and can be used as an energy source by peripheral tissues. SCFAs also modulate gut pH, creating an environment that favors beneficial bacteria while inhibiting the proliferation of pathogenic strains.

Factors influencing RS-microbiota interaction

The interaction between RS and the gut microbiota is influenced by several factors:

• Baseline Gut Microbiota Composition: The existing microbial community in an individual’s gut influences how they respond to RS (Davenport et al., 2015). Individuals with lower baseline levels of certain RS-fermenting bacteria, like Bacteroides, might experience a more pronounced increase in these bacteria upon RS consumption.

• Type of RS: Different types of RS are fermented differently by various bacteria. Classification of RS Bacteria ferments different types of RS differently (Birt et al., 2013). Ruminococcus bromii, for example, has a preference for RS2 from high-amylose maize, while some Bacteroides species may prefer RS3 from retrograded starches.

• Dietary context: Other dietary components such as other fibers, proteins and fats can affect RS fermentation (Macfarlane and Macfarlane, 2003). Soluble fibers may enhance the prebiotic effects of RS, while protein-rich diets could channel some colonic microbiota toward protein fermentation.

• Initial RS intake rapidly alters the microbiota, but long-term RS consumption may stabilize the microbiota (Martínez et al., 2013).

• Host-Related Factors: Age, health status, and genetics also play a role (O’Toole and Jeffery, 2015). Individuals with gastrointestinal disorders may have distinct responses to RS.

RS fermentation in the colon is a synergistic process involving various microbial groups. This process produces SCFAs with significant health benefits for the host. Understanding the factors influencing this interaction is crucial for developing targeted dietary strategies to modulate the gut microbiota and improve overall health.

RS in ready-to-eat meals

George Bernard Shaw is credited with saying, “There is no love sincerer than the love of food.” Food has become more and more important every day. Many people have turned it into a business, including food bloggers, regulators of food quality, producers of RTE foods, and many others. Food that has been partially cooked or prepared in advance and doesn’t need to be cooked or prepared further before consumption is said to be ready to eat. In most cases, this kind of meal doesn’t require any additional preparation before consumption (Mankani and Tata, 2022).

Due to urbanization, cultural shifts, and societal development, India’s eating habits and cooking techniques have drastically changed in recent years. The convenience of RTE has drawn consumers to the fastest-growing food category over the past five years. These food products piqued consumer interest because of their appealing appearance, taste, texture, affordability, and other factors. Various items, such as bakery goods, extruded meals, instant meals, fast food, morning cereals, biscuits, and bars, are the main sources of traditional cereal consumption. Because these food compositions are lightweight, shelf stable, nutritionally enriched, and convenient to purchase and store, they are safe for consumption by humans and well-liked by consumers (Temgire et al., 2021). Since RS can’t be broken down in the small intestine, the colon’s microbiota may ferment it. Although efficient techniques and sophisticated equipment for RS preparation have arisen to match the growing demand for RS, further work is required. Different preparation techniques, the source of starch, and specific nutrients like protein, phenols, including hydrocolloids that interact with RS all have an impact on the amount of RS present. To improve digestive tract health and function and balance the intestinal environment, RS acts as a fermentation substrate by altering and stabilizing the intestinal flora. Even more so than dietary fiber, RS is a type of component with potential physiological action that offers several health advantages. RS can be used extensively in the food business because it also has good food-processing qualities (Jiang et al., 2020). Occurrence of different types of RS are shown in Table 2.

Table 2.

Occurrence of different types of RS

Type of starch	Occurrence	References
RS1	Items made from whole grains or coarsely crushed grains	Nguyen et al. (2023)
RS2	Green bananas, raw potatoes, and high-amylose corn	Thuy et al. (2022)
RS3	Starchy foods like potatoes, rice, pasta, oats, and stale bread that have been cooked and then cooled	Karunarathna et al. (2024)
RS4	Foods containing cross-linked starch or other chemically altered starches	Nurmilah and Subroto (2021)
RS5	Foods with naturally occurring amylose–lipid complexes	Castro-Campos et al. (2024)

Green bananas had the largest quantity of RS in the starch composition analysis, ranging within 35.14 and 45.87%. This means that over half of the total starch in bananas has an RS content within 35.14 and 45.87%, while the RS content in legumes ranges between 2.33 and 10.63% and 1.16 to 4.85% in grains of wheat (Akhtar et al., 2021). The majority of RTE foods must first be cleaned and sterilized to get rid of debris and microbiological load, and then they must be pre-cooled for the cold-chain process. In order to extend the life span of unsterilized ingredients and prevent pathogenic contamination, they must also be treated using antimicrobials in addition to being washed or by incorporating antimicrobial components in the package, such as essential oil, organic acids, chitosan, etc. Following the first washing, RTE foods are subjected to further processes such cutting, peeling fresh vegetables, skinning meat, and removing shells from seafood. These methods significantly cut down on consumers’ cooking time by turning the raw ingredients into almost entirely edible portions, which may help them finish delicate and complicated meal preparation. Another crucial step in giving RTE foods a distinctive flavor and appealing texture is frying. Meal kits, which are made up of separate packs that have been pre-portioned into airtight containers or resealable pouches to guarantee freshness, are among the most exemplary examples. Well-designed meal kits come in certain sizes and consist of distinct containers for each protein source or vegetable, as well as little packaging for liquid sauces and dry spices. In this manner, spills and cross-contaminations can be significantly reduced, and novice users can easily identify and organize (Cui et al., 2024). The unavoidable process of gelatinized starch rearranging into an ordered state during the processing and storage process is known as “retrogradation of starch.” varied kinds of starch granules have varied amylose and amylopectin chains in terms of length, proportion, and structure. The process is influenced by the genetic material and growth conditions of plants. The synthesis of retrograded starch is largely influenced by internal variables, whereas its structural rearrangement is directly influenced by external ones. The establishment of favorable conditions allows food components to influence the reorganization of starch (Chang et al., 2021).

The physicochemical characteristics of potato starch are significantly impacted by gamma irradiation. It lowers the apparent amylose content (AAC), to start. An increasing trend was observed as the irradiation dosage increased when the amylose contents were measured using concanavalin A precipitation method. Therefore, it is possible to speculate that the breakdown of long-chain amylose into short-chain amylose resulted in a number of modifications to the physicochemical characteristics of potato starch. The water being absorbed, gel viscosities, hardness, & gumminess all decreased as a result. In the meantime, it raised the rate of gelatinization and water solubility. It’s interesting to note that gamma irradiation can quicken the potato starch retrogradation process. The disintegration of lengthy chains may possibly be the cause of this occurrence. The levels of RS, especially RS3, are raised by the faster retro gradation & recrystallization of potato starch (Peng et al., 2024). Significant health benefits of RS are illustrated in Fig. 2.

Fig. 2.

Health benefits of resistant starch

Impact of RS on gut microbiota

Prebiotic effects of RS

One of these carbohydrates, RS, is thought to have prebiotic potential when it is chemically or naturally resistant to digestion. The prebiotic potential of type 2, type 3, and type 4 RS that was separated from food and manufactured commercially was evaluated in both in vitro and in vivo investigations. Despite the fact that not all studies have produced excellent findings, the results of recent research suggest that some RS varieties may be potential prebiotic components due to their high prebiotic capability (Tekin and Dincer, 2023). Obesity has spread like wildfire, with developing nations experiencing the highest rates. Research has indicated that dietary consumption can impact human health conditions, such as obesity. Food compounds known as prebiotics have the potential to improve human health by affecting the balance of the gut bacteria. Prebiotic diets can therefore specifically promote the development of good bacteria in one’s gut, which may be a tactic to combat obesity. Among these is RS, a fermentable prebiotic component that can support intestinal health. Because of its capacity to withstand digestion, transit through the colon, and favorably stimulate fermentation of gut microbiota, RS is evaluated in this article as a fiber that is soluble with prebiotic potential. Numerous investigations have also shown metabolites from the intestinal fermentation of RS. According to studies, RS helps regulate body weight by stimulating the gastrointestinal signaling chemicals that regulate hunger, prevent fat from accumulating, and reduce food intake. RS might be a viable strategy to prevent the onset of obesity (Thompson et al., 2022).

One kind of dietary fiber that has prebiotic-like qualities is RS, which can lower fat accumulation, regulate insulin and glucose levels, and shield the intestinal barrier. The gut microbiome is intimately linked to these RS activities. Although the gut bacteria consumed RS to varying degrees, there are notable variations in the rates of utilization. It examined how changes in the glycoside hydrolases that gut microorganisms express affect how RS is used and how these variations affect the structure, content, and metabolism of gut microbes, including tryptophan, bile acids, and short-chain fatty acids. The function of RS associations with intestinal flora in controlling human health, using minerals levels, hyperlipidemia, gastric damage, tumors of the colon, metabolic syndrome, or non-alcoholic fatty liver syndrome (Yan et al., 2024).

Short-chain fatty acid production

SCFAs, including butyrate, acetate, and propionate, are important for human health in a number of ways, including immune system modulation, metabolic pathway regulation, and gut barrier regeneration. To create SCFAs, a variety of microorganisms can break down substrate sources, primarily non-digestible polysaccharides but also, occasionally, proteins. Throughout our lives, the production of particular SCFAs varies based on dietary changes and the resulting changes in our gut microbiota. SCFAs have been studied as a treatment option for a number of illnesses; pre-clinical models have shown encouraging results, but human results have been unsatisfactory since oral SCFAs have poor colonic availability. One of the main therapeutic mechanisms in a number of strategies to alter the gut microbiota, such as diet, probiotics, prebiotics, or FMT, seems to be the rise in SCFAs. It is recommended that more study be done in order to better understand the significance of SCFAs in human illnesses, look into innovative SCFA delivery systems, and clarify the benefits of SCFAs as an alternative therapeutic path of microbiome modulators (Fusco et al., 2023).

The prevalence of childhood obesity is still rising and continues to be a public health concern. Obesity is caused by the gut microbiota, which is also a potential target for treatment. In particular, the fermentation of ordinarily indigestible dietary carbohydrates by microorganisms may provide protection against childhood obesity and metabolic syndrome by producing SCFA. Prebiotics, which are carbohydrates that target the microbiota, have not yet been shown to improve the synthesis of SCFA by gut bacteria in obese children and adolescents (ages 10 to 18). Using an in vitro system, we investigated how the fecal microbiota of 17 obese children produced SCFAs after being exposed to five distinct generic prebiotic supplements. Authors found that the majority of prebiotics were actively digested by the microbiota of all 17 individuals. Nevertheless, the acidogenic potency of supplements differed. There was also notable interdorm variation in SCFA generation, which sequencing of 16S rRNA confirmed was linked to variations in the composition of the host microbiota. Finally, authors discovered no positive correlation between microbial SCFA production capability, fecal SCFA content, or obesity indicators. These in vitro results collectively raise the possibility that the best acidogenic prebiotic may vary from person to person and that generic prebiotic supplements may not all be equally effective in promoting the formation of SCFA in obese children and adolescents (Holmes et al., 2020).

Gut microbiota modulation

Unquestionably, there is growing interest in creating novel functional products that are perfect symbiotic carriers, such as nutrient bars, dairy products, chocolate, juice, frozen desserts, as well as cheese, to guarantee daily consumption of prebiotics and probiotics, which are essential for preserving the microbiota of the gut and general wellbeing. With a focus on the health advantages generated by co-encapsulated symbiotic & immobilized probiotics, this review examines the contemporary strategies that are now being explored to modify the gut flora. The impact of processing, storage, and other simulated gut conditions on the bioactivity and survivability of probiotics and prebiotics, including omega-3 polyunsaturated fatty acid phytochemicals and dietary fibres, are considered using various delivery mechanisms. Despite the symbiotic’ demonstrated biological qualities, research in this field must concentrate on the appropriate selection of probiotic species, their prebiotic equivalents, and delivery methods to prevent the suppression of their complementary or synergistic effects on human health. Future research should focus on creating functional food products with stable symbiotic that are suited for various age groups or especially made to meet the requirements of adjuvant therapy (Kvakova et al., 2021).

It is widely acknowledged that the development of cardiovascular illnesses as well as other chronic/non-communicable pathological conditions, such as cancer, neurodegenerative diseases, and disorders related to aging, are associated with gut microbiota, inflammation, and obesity. Oxidative stress is crucial in this situation. Research indicates that dietary variations around the world may serve as a means of reducing oxidative stress and delaying the onset of oxidative stress-related illnesses. More precisely, numerous national nutritional standards in numerous countries have approved the Mediterranean diet and other dietary patterns centered on the frequent consumption of vegetables and fruits due to their positive health effects. Indeed, these patterns lead to a wealth of certain elements, including fiber, minerals, vitamins, and antioxidants, all of which have been shown to have positive impacts on human health. This implies that certain food components may have nutraceutical value (Deledda et al., 2021). Because prebiotics have the ability to promote the development of potentially beneficial bacterial strains, their inclusion in a gluten-free diet (GFD) may also be a simple and affordable supplementary remedy for celiac disease (CD). Nevertheless, there is currently not enough data to support the use of probiotics and prebiotics in clinical practice when it comes to CD patients (Marasco et al., 2020).

Health benefits of RS from ready-to-eat meals

RS is a type of carbohydrate that resists digestion in the small intestine and acts similarly to dietary fiber. It can be found in various foods, including some ready-to-eat meals. Table 3 summarize the examples of ready-to-eat meals containing RS, their sources, major nutrients, health benefits. Overview of RS ready-to-eat meals health benefits are shown in Fig. 3.

Table 3.

Ready-to-eat meals containing RS

Type of meals	Sources of resistant starch	Major nutrients	Health benefits	References
Chickpea Beverages	Fermented beverages and milk	Protein, carbohydrates, B vitamins, probiotics	Supports digestion and balances gut microbiome	Raza et al. (2019)
Chickpea Instant Food Products	Bread, pasta, soup mix, pancake mix	Protein, fiber	Provides protein and prebiotic fiber that promotes flourishing gut microbiota	Mohamed et al. (2020)
Chickpea Snacks	Protein bars, crackers, biscuits	Protein, essential amino acids, dietary fiber	Enhances production of propionate and butyrate, balancing colonocytes and maintaining mucosal integrity	Martín-Esparza et al. (2023)
Chickpea Dips	Hummus	Protein, fiber	Produces short-chain fatty acids (SCFAs) that decrease carcinogenesis in the gut and increase beneficial bacteria like Bacillus and Bacteroides	Planes-Muñoz et al. (2021)
Chickpea Prebiotic Foods	Yoghurt, Tempeh	Prebiotics, protein, dietary fiber	Promotes gut bacterial growth and aids digestion through prebiotics	Patil et al., (2024); Teoh et al. (2024)
Chilled Pasta Salad	Cooked and cooled pasta	Carbohydrates, fiber	Improves gut health, lowers blood sugar levels	Bojarczuk et al. (2022)
Brown Rice Bowl	Cooked and cooled brown rice	Carbohydrates, fiber	Enhances satiety, aids in weight management	Chen et al. (2022)
Legume-Based Meal	Lentils or beans	Protein, fiber	Supports digestive health, promotes beneficial gut bacteria	Curran (2012)
Potato Salad	Cooked and cooled potatoes	Carbohydrates, fiber	Increases feelings of fullness, may reduce risk of colon cancer	Guo et al. (2023)
Whole Grain Wraps	Whole grain tortillas	Carbohydrates, fiber	Improves insulin sensitivity, helps regulate blood sugar	Bojarczuk et al. (2022)

Fig. 3.

Overview of RS ready-to-eat meals health benefits

Improved digestion and gut health

When bacteria consume RS, they produce SCFAs, which are important for gut health, as well as butyrate, an important energy source for gut microbiomes and enterocytes (intestinal cells). RS does not get digested in the small intestine like other starches but travels to the colon where beneficial gut bacteria ferment it. SCFAs are the by-products of this fermentation process, mainly butyrate, acetate, and propionate, which are important for maintaining a stable gut environment (Chen et al., 2022; Guo et al., 2023). Both of these SCFAs have something in common, but butyrate, in particular, is important for the lining of the colon because it’s the primary energy source for colonocytes, the cells that make up the lining of the colon. Butyrate nourishes these cells, supporting gut barrier integrity to block harmful microorganisms from passing into the bloodstream and facilitate nutrient absorption (Wang et al., 2025b).

In addition to its energetic function, butyrate induces mucin production: a protective glycoprotein that covers the gut epithelium to prevent infection and inflammation (Liao et al., 2025). The enteric nervous system acts on gut motility to regulate bowel movements; thus, RS‐derived SCFAs are involved in the regulation of gut motility. The gut microbiota helps to maintain a healthy bowel function and prevents disorders including irritable bowel syndrome (Harush et al., 2025). Fiber not only prevents constipation but also regulates healthy bowel function and metabolism. RS is a powerful prebiotic that helps the cultivation of beneficial gut bacteria such as Bifidobacterium and Lactobacillus. This would promote a diverse, balanced gut microbiome; key to preventing gut dysbiosis, which is linked to a complex group of GI diseases. The correlation between healthy conditions and diversity of microbiome and risk of digestive disease conditions (Heshmati and Abdollahzad, 2024). RS moreover enhances tight junction protein expression, promoting gut barrier integrity, and prevents “leaky gut,” where niosome harmful substances directly to inside the intestines get their way into the bloodstream and may potentially characterize systemic inflammation and immune-mediated disorders. For example, RS consumption reduces intestinal inflammation and promotes a more favorable gut microenvironment, thereby relieving some symptoms associated with a functional GI disorder (e.g., irritable bowel syndrome. Its ability to absorb and expand water creates greater ballast to prevent constipation by guaranteeing the necessary motion in the form of fecal movements (Xu et al., 2025).

Recent studies may further examine what’s called the gut-brain axis the communications line between the gut and the central nervous system (CNS) as one more way that RS is influencing the brain. RS may help to prevent or reduce the severity of neurological diseases related to gut dysbiosis and systemic inflammation, possibly by benefiting gut health and ameliorating inflammation. RS is an excellent dietary item that improves digestive fitness, strengthens gut microbiome variety, and aids a healthy gut barrier. As a preventer and manager of diverse conditions, including constipation, irritable bowel syndrome, inflammatory bowel disease and leaky gut syndrome, fiber has manifold benefits but also nourishes global health (Rao and Gershon, 2016).

Anti-inflammatory effects

RS boasts a hell of a resume for its super-potent anti-inflammatory properties, significantly attributable to its fermentation in your colon yielding SCFAs butyrate, propionate, and acetate. Of these, butyrate is particularly critical for gut local inflammation mitigation, and systemic anti-inflammation. Besides this, butyrate also plays an important part in these sites by reducing the production of mediators of inflammation TNF-α and IL-6, which are involved in the inflammatory processes related to chronic inflammation diseases such as inflammatory bowel disease (IBD) and colorectal cancer (Cheng et al., 2025). These pro-inflammatory markers are involved in mediating balance in the immune system and reducing the likelihood of chronic inflammation which this inhibition tries to encourage. In addition to the localized anti-inflammatory actions in the gut, RS also promotes the production of Tregs, which are critical for dampening immune responses and limiting inflammation. Given that, these Tregs play an important role in preserving immune homeostasis and preventing peripheral organ autoimmunity. Moreover, SCFAs, including propionate, can likewise influence Treg differentiation that initiatively enhances the anti-inflammatory ability of the body (Liao et al., 2025). RS additionally lowers the pH in the colon thereby causing an acidotic environment that is less supportive for pathogenic bacterial growth. These dietary changes favor the beneficial bacteria, reduce gut inflammation and promote better immune responses. Downriver effects in the gut could mean a whole-body impact, including a lowered risk of a whole host of chronic inflammatory diseases such as cardiovascular disease, metabolic syndrome and degenerative brain diseases.

RS is increasingly known for its anti-inflammatory properties, another important health benefit. Butyrate helps to provide energy to colon cells but is also important for gut immune regulation (Heshmati and Abdollahzad, 2024). Butyrate inhibits the release of pro-inflammatory cytokines and induces the expression of anti-inflammatory molecules. In IBD such as Crohn’s disease and ulcerative colitis, alleviating gut inflammation alleviates symptoms and improves quality of life, making this mechanism particularly useful for those suffering from these diseases (Guo et al., 2023). In addition, RS intake has been associated with favorable changes in systemic inflammation marker(s). It has been demonstrated that greater Biomarkers of Inflammation, including levels of C-reactive protein (CRP), which is often associated with inflammation potentially contribute to a variety of chronic diseases (such as cardiovascular disease) (Heshmati and Abdollahzad, 2024), could be reduced with daily RS. This ability to modulate inflammation is not confined to the gastrointestinal tract but rather extends to modulate systemic inflammation, a contributing factor to metabolic disorders and other chronic diseases. The ability of RS to modulate both local and systemic inflammation is the basis for RS’s overall health benefits. Thus, RS can have a significant impact on lowering the incidence of chronic inflammatory diseases and promoting general health through mediating balanced microbiota impaired or SCFA production or immune modulation.

Metabolic benefits

RS has drawn attention due to its large metabolic improvements, especially in terms of blood glucose, insulin sensitivity, lipid metabolism, and managing body weight. Unlike normal starch, RS is indigestible in the small intestine and results in a slower, steadier release of glucose into the blood. This means that it has a lower glycemic index than rapidly digestible starches, so RS is a great option for people trying to control their blood glucose levels and is especially valuable in patients with type 2 diabetes and at risk of metabolic syndrome (Hussain et al., 2025). RS helps prevent spikes in blood sugar which are essential in controlling the level of range of blood sugar to avoid insulin resistance or type 2 diabetes. Both these metabolic advantages of RS go hand in hand, for one of the most well-known metabolic benefits of RS is the enhancement of insulin sensitivity. Fermentation of RS leads to the production of SCFAs, such as butyrate, which has been correlated with improved insulin sensitivity by suppressing inflammation and oxidative stress, two key drivers associated with insulin resistance (Zhang et al., 2025). In addition, animal studies indicate that RS can enhance insulin secretion and decrease ectopic fat accumulation, which also supports metabolic health (Niu et al., 2025). These effects highlight the promising potential of RS to improve glycemic control and prevent or manage insulin resistance.

Potential for disease prevention

RS and has received much attention due to its putative role in the prevention of diseases such as colorectal cancer, cardiovascular diseases, and metabolic disorders. Gut bacteria ferment RS a form of dietary fiber that is not absorbed in the small intestine into short-chain fatty acids (SCFAs), such as butyrate. Butyrate is crucial for the maintenance of metabolic homeostasis in the intestine and is implicated in protective roles in the pathogenesis of chronic diseases. An area where RS has shown such promise is in the prevention of colorectal cancer. SCFA produced in the colorectal microbiota following the fermentation of RS such as butyrate have been shown to have effects on preventing tumorigenesis by triggering apoptosis (programmed cell death) of cancer cells and also reducing colon inflammation (Heshmati and Abdollahzad, 2024). A diet high in fiber (including RS) has been consistently associated with a decreased risk of colorectal cancer in epidemiological studies. Butyrate also plays a significant role in preserving the function of the colonic epithelium, serving as a barrier to carcinogens, thereby further limiting the potential for cancer development (Kumari et al., 2025).

Sensory characteristics and consumer acceptance

Most individuals worldwide get 60–70% of their energy from starch-based foods because of the unquestionable nutritional value of starch (Brinck et al., 2025). More consumers than ever before are accepting starch-based products due to their accessibility and low cost. However, because sensory qualities are crucial in ready-to-eat meals and are a major factor in determining customer acceptance, choosing the right dietary fibre is essential. A study by Cervini et al. (2021) found that gluten-free (GF) pasta examples were created using rice flour substituted with 0, 5, 10, and 15 g/100 g (w/w) of an RS component made from annealed sorghum starch (annRS). They discovered that adding up to 15 g/100 g of annRS to GF pasta can help produce GF items with a high level of total dietary fibre, slowly digested starch, and few sensory properties (Cervini et al., 2021). In order to enhance the nutritional profile, dry pasta is generally seen as a product that can be reformulated as GF (Evangelista et al., 2025). Partially substituting new, nutrient-dense components for typical GF flours and/or starches is one of the most adaptable approaches in this regard (Delgado-Pando et al., 2025). When it comes to the raw materials, using substances high in RS is becoming more and more important when creating GF pasta (Fitriati et al., 2025). Processing parameters like pH, moisture, temperature, processing pressure, freezing, autoclaving, and storage conditions have been shown to have an impact on the development of certain RS types, particularly RS3 (Ma et al., 2020). RS3 raises the overall dietary fiber of fried battered items since it can withstand even the highest frying temperatures (Liu et al., 2023). In the meantime, RS3 prevented moisture loss and served as a barrier to stop the absorption of fat (Kasote et al., 2018). The WBC of amylose may be higher than that of native starch based on its structural characteristics. Reduced water activity (a_w) in RS is caused by reduced water holding capacity (WHC) and increased water binding capacity (WBC), extending the product’s shelf-life. Reduced a_w can also help avoid ice crystals and a gritty texture in ice cream when freezing dairy products (Acar et al., 2025). Miller and Bianchi (2017) found that, among 97 consumers in an untrained panel, RS-enriched white pan bread did not substantially vary in terms of flavour, texture, or overall bread liking at replacement levels of 15%, 20%, and 25% conventional flour (Miller and Bianchi, 2017). Comparing pasta formulations with 7.5 and 10 g/100 g of RS4 and RS2 to control pasta, Bustos et al. (2011) observed that there was no change in overall acceptance (Bustos et al., 2011). In addition, Alviola et al. (2012) observed that tortillas made with 15% Fibersym RW (RS4) (flour basis) were more widely accepted than the counterpart (Alviola et al., 2012). The addition of RS to food products may benefit the consumer in many ways (such as lowering the glycaemic index compared to their conventional counterparts), while also benefiting the manufacturer by enhancing the food’s technological and/or sensory qualities and producing a fiber-enriched product that tastes and looks as good as its nonenriched control. Consumer knowledge of RS and its possible health benefits is probably lacking, though. The marketability of RS-enriched foods and its acceptance may both be enhanced by greater nutritional awareness of RS.

Opportunities and limitations

One major restriction in RS research is the inherent diversity in RS sources. While it is known that RS can be present in foods including legumes, grains, and certain tubers, the exact amount varies greatly depending on factors like type, ripeness, processing, and cooking methods (Choudhary et al., 2024). For example, the amount of RS in a banana varies with ripening; immature bananas have higher levels of RS than ripe bananas (Phillips et al., 2021). Similarly, the technique of cooking and cooling starchy foods such as potatoes or rice might influence their RS content (Kim et al., 2020). This diversity complicates the development of dietary interventions and the application of findings from one study to a larger context.

Additionally, reactions to RS can differ greatly across individuals. Numerous factors can affect how one processes and benefits from RS intake, including age, genetics, gut microbiota makeup, and general health state (Golshany et al., 2025). When two people consume the same quantity of RS, for instance, they may exhibit different patterns of short-chain fatty acid synthesis in the colon or varied postprandial glucose reaction. Furthermore, different people may have different gut microbiota capacities for fermenting RS into advantageous metabolites, especially those with a more diverse microbiota than those with a less diverse microbial community (Brinck et al., 2025). To tackle these issues in the context of RS research, more thorough cohort studies, interdisciplinary cooperation, and rigorous experimental designs are needed. This would include data scientists, geneticists, microbiologists, and nutritionists in addition to dietitians and nutritionists in order to fully utilise RS in human health.

The various roles of RS in human health have emerged as an important subject in current nutritional studies. RS greatly affects gut flora resulting in favourable metabolic outcomes, especially in metabolic syndrome, weight loss, obesity, diabetes and glycaemic control. Future RS studies may also be focused on developing ways to isolate and characterize RS1 and RS5 to investigate their potential health-enhancing effects and applications in food and health industries as well. Having global consensus characterization protocols would lead to accurate quantification of resistant starches thus contributing to the update of product labelling and nutritional databases to estimate the population exposure to resistant starches and their contribution to the daily fiber intake. Furthermore, the determination of an acknowledged energy contribution for RS is essential, as the existing US food labelling regulations that classify RS as a noncaloric component may be deceptive. If the contribution of RS is inaccurately represented on food labels, daily energy intakes may be underestimated, thereby complicating the interpretation of energy balance studies.

Abbreviations

RS

Resistant starch

SCFAs

Short chain fatty acids

FFAs

Free fatty acids

RTE

Ready-to-eat

FAO

Food and Agricultural Organization

MACs

Microbiota accessible carbohydrates

GFD

Gluten-free diet

WHC

Water holding capacity

WBC

Water binding capacity

IBD

Inflammatory bowel disease

LDL

Low density lipoprotein

CRP

C-reactive protein

AAC

Apparent amylose content

ALCs

Amylose lipid complexes

CNS

Central nervous system

Funding

No funding was received from any source for conducting this study.

Data availability

As this is a review work, no data was used for this study.

Declarations

Conflict of interests

There is no conflicts of interest between the authors.