Prebiotic Type Spotlight: Resistant Starch

Each edition of GPA’s Prebiotic Spotlight focuses on a specific prebiotic type to raise awareness around the prebiotic itself, its sources, any notable and/or recent research, and how it is used in the marketplace. This report examines the role of resistant starch (RS) and emphasizes its effects in gastrointestinal conditions such as irritable bowel syndrome (IBS) and chronic constipation, along with its influence on the gut microbiota and broader digestive and metabolic functions.  

Overview 

Maintaining a healthy gut microbiota is essential, as the gut regulates metabolic processes and inflammatory responses, while also playing a key role in fat storage and glucose metabolism (Li et al., 2024). Many individuals turn to dietary interventions to support a balanced gut microbiota, with RS being one effective approach. RS is a type of dietary fiber that bypasses digestion in the small intestine due to its resistance to amylase, reaching the large intestine where it is fermented by gut microbiota (Luk-In et al., 2024). Upon fermentation, RS produces high amounts of short-chain fatty acids (SCFAs), contributing to its benefits on the gut microbiome. These benefits include improving digestion and gastrointestinal transit, strengthening the lining of the gut, reducing the formation of gallstones, enhancing mineral absorption, modulating fat oxidation, among others (Luk-In et al., 2024; Niu et al., 2025).  

Benefit Areas 

A growing body of research suggests that RS can beneficially influence the human gut microbiota and support healthy gastrointestinal function (Wen et al., 2023), with recent evidence highlighting its health effects in the following areas:  

• Supplementation with RS type 2 in adults with chronic kidney disease led to changes to microbiota composition, including reductions in alpha diversity, increased abundance in Subdoligranulum and Oscillospiraceae, and decreased Bacteroides (Headley et al., 2025).  

• Substituting a proportion (~15%) of dietary starch with RS help to manage glycemic control such as reducing blood glucose levels in adults with type 2 diabetes (T2D), without significantly altering palatability (Collins et al., 2025). 

• Sago starch (Metroxylon sagu Rottb.) contains high amounts of RS type 2, and when consumed by individuals with T2D led to reductions in daily caloric intake from daily meals (King et al., 2025) 

• Among individuals with excess body weight, supplementation with RS leads to improved glucose tolerance, insulin sensitivity, and adiponectin, as well as reductions in body weight, fat mass, and waist circumference (Li et al., 2024).  

• Canna edulis RS type 3 is an insoluble dietary fiber that can decrease serum total cholesterol and non-high-density lipoprotein cholesterol after daily consumption among participants with mild hyperlipidemia (Miao et al., 2024). 

Sources 

There are five different subtypes of RS, categorized based on their resistance to digestion in the gut, which include RS type 1, type 2, type 3, type 4 and type 5. RS type 1 is commonly found in whole or partially milled grains, where it remains physically inaccessible since its proteins, cell-walls, and lipids act as a protective encapsulation. RS type 2 is commonly found in high-amylose maize starch, raw potatoes, and/or green bananas, and consists of ungelatinized resistant granules. RS type 3 is formed when cooked potatoes are cooled and is referred to as retrograded starch. RS type 4 is commonly found in chemically modified starch, and RS type 5 can be found in foods with high amylose content. Research has suggested that RS types 1 and 2 are especially studied in the context of glucose control, and RS type 3 has shown to resist to pre-colonic digestion by amylase and stimulates the production of SCFAs. Comparatively less research has assessed the health effects of RS types 4 and 5; however, it is suggested that RS type 4 may alter circulating secondary bile acid production, indicating modulation of the gut microbiome (Dhakal & Dey, 2022). Also, RS type 5 is known to be highly resistant to enzymatic digestion and stable given its tight bonds with starch molecules (Dong et al., 2025a; Dong et al., 2025b; Luk-In et al., 2024; Malcomson et al., 2024).  

RS type 4 (RS4) is not naturally found in foods but is produced through chemical modifications such as esterification, etherification, and cross-linking that make it highly resistant to digestion. Once fermented in the colon, RS4 produces postbiotics such as SCFAs (e.g., acetate, butyrate, and propionate), indoles, bile acids, and precursors for neurotransmitters such as serotonin and gamma-aminobutyric acid. Postbiotics elicit various beneficial effects in the gut, including attenuating inflammation, modulating the gut-brain axis, regulating immune responses, strengthening the intestinal barrier, and potentially benefiting conditions like IBS (Kovacs et al., 2025; Smith et al., 2024).  

Dose Range 

RS is included in Health Canada’s definition of dietary fiber. Health Canada’s daily intake recommendation for dietary fiber is 25 g for women and 38 g for men; however, most Canadians do not meet this target (Health Canada, 2025). In the United States, Birt et al. (2013) reports that a minimum of 6 g of RS per meal is recommended; however, the daily intake of RS totals at approximately 5 g per day. This may be due to the fact that many common foods in the Western diet, such as rice, pasta, and breakfast cereals are low in fiber and have a high glycemic index (Birt et al., 2013). More recently, Drake et al. (2022) suggested that the daily intake of 15-20 g of RS is needed to observe health benefits. Nonetheless, daily RS consumption within regions such as the United States, Australia, and Europe remains between 3-9 g per day (Drake et al., 2022). As such, global consumption of dietary fiber, including RS, is lacking globally.  

Recent Research 

Recent research on the oral use of RS is emerging as a key area of interest. Currently, there are twenty ongoing clinical studies listed on ClinicalTrials.gov evaluating the effects of RS on various health conditions including constipation, overweight or obesity, cirrhosis, T2D, polycystic ovary syndrome (PCOS). Additional studies are investigating its impact on markers of health such as on cognition and aerobic endurance (ClinicalTrials.gov, 2025). On PubMed, a search for ‘resistant starch’ filtered for clinical trials and randomized controlled trials within the past 5 years yielded 51 results. These studies examined the effects of RS in patients with conditions such as Non-Alcoholic Fatty Liver Disease (NAFLD), T2D, chronic constipation, and hemodialysis. Other effects were assessed on changes to the composition of the gut microbiota and appetite (PubMed, 2025). Below are 3 human clinical trials found on the PubMed database that assessed the effects of RS on IBS and chronic constipation.  

Bush and Alfa (2024) conducted a post hoc analysis of a 3-arm randomized, double-blind, placebo-controlled trial assessing the effects of resistant potato starch (RPS) in abnormal bowel symptoms in 70 healthy adults (aged 18-69 years). The investigational product was an unmodified RS type 2 (Sonul®), with treatment arms consisting of 7 g/day RPS (4.2 g RS), 3.5 g/day RPS (2.1 g RS), and 7 g/day placebo (digestible corn starch). Outcomes assessed during the study included abdominal pain, belching, bloating, gas, and overall well-being using the Gastrointestinal Quality of Life Index, and bowel movements using the Bristol Stool Chart. In addition, 3-day food records and microbiome analyses were collected. Results suggest dose-dependent correlations between bowel symptoms and bacteria taxonomic groups. Specifically, consumption of RPS was able to modulate gastrointestinal symptoms including belching, bloating, and constipation, with significant positive correlations observed in changes in Papillibacter, Lachnospira, Granulicatella, Turicibacter, Haemophilus, and unclassified Pasteurellaceae, unclassified Enterobacteriaceae, unclassified Gammaproteobacteria, and unclassified Fusobacteriaceae. Additionally, consumption of RPS modulated belching, with significant negative correlations in Dorea and unclassified Coriobacteriaceae during consumption of either 3.5 g/day and 7 g/day of RPS. Overall, both positive and negative correlations were observed between changes in abnormal bowel symptoms and specific microbiota following consumption of type 2 RS. Energy-dense foods are commonly used to address childhood malnutrition; however, these are typically high in fat and calories and often do not reduce the incidence of relapse. An alternative strategy may be to target the immature gut microbiota, addressing malnutrition-related intestinal changes. Mostafa et al. (2024) conducted an analysis of a randomized controlled trial to assess the effects of supplementation with a gut microbiota-directed complementary food (MDCF-2) to improve gut health and inflammation in children with moderate acute malnutrition (MAM). The study included 124 children (aged 12-18 months) with MAM, who were randomized to receive either 1) MDCF-2, or 2) ready-to-use supplementary food (RUSF) for 12 weeks, with 2 weeks pre-intervention period and 2 weeks follow up. MDCF-2 contained chickpea, soybean, peanut, green banana, sugar, and soybean oil, supplemented with micronutrients (vitamin and mineral mix). RUSF consisted of rice, lentils, milk powder, sugar, soybean oil, and micronutrients. Measurements included assessment anthropometric, stool, and plasma markers, which were assessed pre-and post intervention. Results suggest that children treated with MDCF-2 experienced significant increases in plasma citrulline concentrations and decreases in alpha-1-antitrypsin compared to children consuming RUSF. These results suggest a potential benefit of MDCF-2 on the gut microbiome in children with malnutrition.  

A randomized, double-blind, two-arm, controlled study protocol was designed to assess the effects of RS consumption from different types of rice in older adults (≥ 60 years) with chronic constipation. Participants are randomized to consume either: 1) A rice (11-20% RS) or 2) B rice (control; 0.1-0.5% RS) daily, for 24 weeks. Per 100 g of rice, A rice provided 1484 KJ energy, 7.12 g protein, 0.3 g fat, 79.5 g carbohydrates, and 3.31 mg sodium, while B rice provided 1480 KJ energy, 5.8 g protein, 0 g fat, 80.2 g carbohydrates, and 0 mg sodium. The primary outcome is constipation symptoms, assessed using the Wexner questionnaire. Secondary outcomes included QoL, depression, anxiety, and sleep quality, evaluated using the Patient Assessment of Constipation Quality of Life questionnaire, the Zung Self-Rating Depression Scale, the Zung Self-Rating Anxiety Scale, and the Self-Rating Scale of Sleep, respectively. Study outcomes are to be measured at baseline, week 6, week 12, and week 24 of the intervention. This study aims to provide insights into how RS intake influences chronic constipation and gut microbiota. It will also explore the relationship between these changes and the gut–brain axis, assessing the potential links of RS to depression and anxiety in older adults (Zhao et al., 2024). 

Another randomized, double-blind, placebo-controlled clinical trial aimed to assess the effects of supplementation with RS type 3 in adults with self-reported chronic constipation. A total of 98 healthy adults, including 49 young adults (aged 20-40 years) and 49 older adults (aged 41-60 years) were included. Participants were randomized into the following treatment arms: 1) 9 g of RS type 3 (RS-3; sourced from ginko nut, spinach, corn, and brown rice) or 2) placebo (food-grade Soy Protein), daily for 12 weeks. Fecal samples, fasting blood glucose, anthropometric measurements, body composition, stool frequency, and stool consistency were collected at weeks 0, 6 and 12. Additionally, food/fluid intake and physical activity data were also collected. Constipation Scoring System (CSS) and Bristol Stool Scale (BSS) were used to assess stool frequency and consistency. Results suggested that participants taking RS-3 showed a significant increase in BSS scores at week 6 compared to baseline. Also, CSS scores significantly decreased in both placebo and RS-3 groups. Notably, participants taking RS-3 showed a trend toward greater improvements in BSS and CSS scores, as well as bowel movements, compared to placebo. By week 12, beta-diversity of the RS-3 group demonstrated a significant change compared to that of the placebo group, while no changes were observed in alpha diversity. Lastly, the relative abundance of Bifidobacterium, Akkermansia, Fusobacterium, Catenibacterium, and Megamonas significantly increased after 12 weeks of supplementation with RS-3. Overall, this study suggests that supplementation with RS leads to changes in gut microbiota, which may be associated with improved bowel movement (Luk-in et al., 2024). 

How is RS used in the marketplace? 

RS is a versatile food ingredient that is valued for its various benefits to human health, and gaining attention as consumers shift toward low-glycemic foods (Future Market Insights, 2025). RS can be incorporated into food products for their beneficial effects on gastrointestinal health, weight management, and blood glucose management. Also, interest in prebiotic supplementation, satiety, and clean-ingredient label products contribute to the growing interest in RS products. Overall, the addition of these ingredients presents an appealing market opportunity given the increased global prevalence of chronic disease such as T2D and obesity (Future Market Insights, 2025).   

According to Future Market Insights Inc., Resistant Starch Market Outlook from 2025 to 2035 highlights growth in the global RS market driven by increasing awareness of gastrointestinal health among consumers. The market is estimated to reach 7.1 billion USD in 2025 and expected to grow to 15.3 USD by the year 2035. This is given the Compound Annual Growth Rate (CAGR) rate of 8% over this 10-year period. Country-specific projected growth rates for 2025-2035 are 6.5% for the United States, 6.2% for Germany, 6.8% for China, 6.0% for the United Kingdom, and 5.8% for Australia. Interestingly, RS type 2 is favored due to its thermal adaptability, resistance to digestion, and beneficial effects on gut health (Future Market Insights, 2025). 

RS holds an interesting position in the market for low-glycemic food products and other future applications, yet remains under consumed globally, particularly in Westernized diets. RS has five subtypes RS type 1 to RS type 5 which differ based on their resistance to digestion. Each type of RS plays critical roles in modulating the gut microbiota, enhancing SCFA production, management of chronic disease such as T2D, promoting the growth of beneficial bacteria, and other health benefits.