Retrograded starches enable the development of low-GI foods which benefit blood sugar management and weight control, says science educator Alex Ruani.
Retrograded starch, also known as resistant starch type three (RS3), is formed through the heating and subsequent cooling of starch. While it does not naturally exist in significant amounts in raw or unprocessed foods, it is created during the processing and storage of foods like potatoes, rice, bread, and pasta — when the starch molecules realign into a more resistant, crystalline structure. This alters the starch’s properties, making it more resistant to digestion.
In the 1990s, scientists found that retrogradation reduces the GI of starches (usually foods such as pasta and potatoes have a high GI). Since then, several research projects have explored the dietary implications of consuming foods rich in retrograded starch, both in terms of gut health and broader metabolic outcomes.
The food industry has long employed high amylose starches to improve the texture and shelf life of food products, however, as scientific knowledge around their health properties deepens, they are becoming more attractive as ingredients in health-focused and functional foods.
Alex Ruani, University College London (UCL) doctoral researcher in nutrition science education and chief science educator at The Health Sciences Academy, told Fi Global Insights: “Retrograded starches offer significant potential for the food industry by enabling the production of low-GI foods, which are beneficial for blood sugar management and weight control. The ability of retrograded starches to resist digestion makes them valuable in developing functional foods that support gut health and promote satiety.”
Ruani identified five platforms on which the food industry could harness the properties of retrograded starches: low-calorie; gut health; blood sugar management; satiety and weight management; and sports nutrition.
She explained that RS3 is useful in the production of low calorie foods because it resists digestion in the small intestine, resulting in fewer calories being absorbed by the body.
“Studies show that retrograded starch can significantly reduce the available energy [calories] in food, as it is more likely to pass through the digestive system without being fully broken down. This helps control blood sugar levels, prolong satiety, and contribute to overall calorie reduction in food products,” Ruani explained.
RS3 has probiotic potential, supporting the growth of beneficial gut bacteria in the colon by serving as a fermentable fibre.
“When RS3 is fermented by colonic bacteria, it produces short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate. These SCFAs play a crucial role in gut health by reducing the pH in the colon and mitigating the growth of harmful bacteria. Butyrate, in particular, is known to support gut barrier function and even play a role in regulating appetite and supporting brain health,” said Ruani.
The blood sugar management benefits of RS3 relate to its lower GI; the presence of RS3 in foods slows digestion, leading to a more gradual release of glucose into the bloodstream, Ruani noted.
“This may help prevent unwanted spikes in blood glucose levels, making it particularly advantageous for people with diabetes or those managing their blood sugar,” she added.
Because the presence of RS3 makes food digest more slowly, it can help delay gastric emptying and prolong feelings of fullness, assisting weight management, Ruani said, explaining the mechanism at work: “Butyrate and propionate, two of the SCFAs produced by gut bacteria during the fermentation of RS3, can stimulate the release of gut hormones such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). These hormones are well-known for their ability to suppress appetite and slow gastric emptying.”
She suggested that this mechanism makes RS3 a valuable component in dietary strategies aimed at reducing food intake, weight management, and obesity risk mitigation.
RS3 is already available in sports supplements, primarily in the form of resistant starch powders, prebiotic fibre supplements, meal replacement shakes, protein bars, and carbohydrate supplements.
“These products leverage the slow digestion and prebiotic benefits of RS3 to support sustained energy release and reduced blood glucose responses/spikes,” Ruani noted.
However, she added that due to their slow absorption, hydrothermally modified starch supplements (i.e. with a high RS3 content) are not recommended during exercise, as they may cause gastrointestinal discomfort.
Ruani said the food industry is beginning to harness this potential, particularly in the production of snacks, baked goods, and meal replacements that incorporate retrograded starch to improve nutritional profiles.
“For instance, companies are using high-amylose maize starch to create products with enhanced fibre content and lower GI, which cater to health-conscious consumers,” she said.
