Resistant Starch Foods: Cooked-and-Cooled Starches, Green Bananas and Beans
What resistant starch is, which foods contain it, what trials of cooled rice, pasta and green banana found, and cautions for people who use insulin.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read functional food safety before you use anything on this page.
Resistant starch is starch that escapes digestion in the small intestine and reaches the large intestine, where gut microbes ferment it. One review describes four main types: starch protected by intact plant cell walls (type 1), starch with a high amylose content (type 2), starch that has re-formed after cooking and cooling, called retrogradation (type 3), and chemically modified starch (type 4). [1] This page is about resistant starch in everyday foods. Most trials, however, used measured amounts of a resistant starch ingredient or a food that was tested under lab conditions, so they do not show what eating a normal meal does.
Safety first for people who use insulin. In a 2022 study of 32 adults with type 1 diabetes, rice that was cooled for 24 hours at 4 degrees C and reheated gave a lower blood sugar rise, but also more low-blood-sugar episodes (12 versus 3 episodes) with a standard insulin dose. [2] A 2026 crossover study of 32 adults on insulin pumps found cooled and reheated pasta lowered the blood sugar rise without more low-blood-sugar episodes. [3] The results differ, so anyone who uses insulin should ask their diabetes team before changing how they eat starchy foods.
Where resistant starch comes from
An analysis of US national survey data (NHANES 2015-2016) estimated that adults ate about 1.9 g of resistant starch per 1,000 kcal a day. The food categories contributing most often were fried white potatoes, rice, and beans, peas and legumes. [4]Cooling cooked starch is known to cause retrogradation, which raises resistant starch. [5] What trials measured:
| Food | What was tested | Resistant starch found |
|---|---|---|
| White rice | Freshly cooked, cooled 10 hours at room temperature, or cooled 24 hours at 4 degrees C and reheated | 0.64, 1.30 and 1.65 g per 100 g [5] |
| Chickpea pasta | Freshly cooked versus cooled 24 hours at 4 degrees C and reheated | 1.83 versus 3.65 g per 100 g [6] |
| Pasta (type 1 diabetes study) | Freshly cooked versus cooled and reheated | 8.03 versus 12.88 g per 100 g [3] |
These are laboratory numbers in small studies, and the values differ between studies. We do not give cooking or cooling instructions here.
What research shows
| Question | What the source found | Strength of evidence |
|---|---|---|
| Blood sugar control | A meta-analysis of 19 randomized trials found resistant starch lowered fasting glucose slightly (about 0.09 mmol/L) compared with digestible starch. [7] | Promising but limited (mostly measured amounts of ingredients, not meals) |
| Which type | A 2023 meta-analysis of 31 trials in prediabetes or type 2 diabetes found types 1 and 2 lowered after-meal glucose; types 3, 4 and 5 need more research. [1] | Insufficient evidence for type 3 |
| Cooled rice or pasta eaten in a meal | In 15 healthy adults, cooled and reheated white rice gave a lower blood sugar response than fresh rice. [5] Chickpea pasta had a lower glycemic index after cooling (33 versus 39) in 12 healthy adults. [6] | Promising but limited (small, short, after-meal only) |
| Green banana biomass | In a trial of 113 adults with prediabetes or type 2 diabetes, 40 g of biomass (about 4.5 g resistant starch) for 24 weeks was linked to lower HbA1c, but the comparison group (diet alone) also improved in some measures. [8] | Mixed |
| Gut microbes | A review of 13 human and 35 animal studies of type 2 resistant starch found more short-chain fatty acids but results varied between studies. [9] | Promising but limited |
"Biomass" here means a green banana preparation used in the trial; we do not describe how to make it. Proper evidence not found: we searched PubMed for trials of cooked-and-cooled potatoes on blood sugar and found no record to read.
Related pages
Legumes, foods and blood sugar, prebiotic foods and prebiotic fiber supplements.Frequently asked questions
What is resistant starch?
Starch that escapes digestion in the small intestine and is fermented in the large intestine. [1]
Do cooked-and-cooled potatoes, rice and pasta have more resistant starch?
Trials measured more resistant starch after cooling rice, chickpea pasta and pasta. [5] [6] [3]
Is a green banana a good source?
Green banana biomass was used in one 24-week trial with mixed findings. [8] We found no official intake level for green banana.
Can I eat cooled rice safely?
The NHS says to cool cooked rice within 1 hour and refrigerate it, and to eat it within 24 hours. [11]
Is resistant starch safe if I have diabetes?
It depends on treatment. People who use insulin had more low-blood-sugar episodes in one study and not in another, so ask the diabetes team. [2] [3]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and individual considerations
- Food poisoning: a 2024 review links Bacillus cereus illness from rice to improper storage temperature during cooking, cooling and reheating. [10] The NHS says to cool cooked rice within 1 hour, refrigerate it and eat it within 24 hours. [11] The room-temperature step in the 10-hour rice study is not a safe-handling model. See food safety basics.
- Gas and bloating: fermentable carbohydrates can cause abdominal discomfort and gas, especially at higher intakes. [12]
- Diabetes medicines: see the insulin note above; a pharmacist or clinician can advise on other medicines.
- Pregnancy, children, kidney or liver disease: not described in the sources we read for this page.
References
- Pugh JE et al. A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes or prediabetes: A systematic review and meta-analysis. Frontiers in nutrition 2023. PMID 37051127. Read 2026-10-23.
- Strozyk S et al. Influence of resistant starch resulting from the cooling of rice on postprandial glycemia in type 1 diabetes. Nutrition & diabetes 2022. PMID 35429987. Read 2026-10-23.
- Rogowicz-Frontczak A et al. Does Resistant Starch Formed by Cooling Pasta Decrease the Postprandial Glycemic Response in Type 1 Diabetes? A Randomized Single-Blind Crossover Study. Nutrients 2026. PMID 41978202. Read 2026-10-23.
- Miketinas DC et al. Usual Dietary Intake of Resistant Starch in US Adults from NHANES 2015-2016. The Journal of nutrition 2020. PMID 32840627. Read 2026-10-23.
- Sonia S et al. Effect of cooling of cooked white rice on resistant starch content and glycemic response. Asia Pacific journal of clinical nutrition 2015. PMID 26693746. Read 2026-10-23.
- Bojarczuk A et al. The Effect of Cooking and Cooling Chickpea Pasta on Resistant Starch Content, Glycemic Response, and Glycemic Index in Healthy Adults. Metabolites 2024. PMID 39590821. Read 2026-10-23.
- Xiong K et al. Effects of resistant starch on glycaemic control: a systematic review and meta-analysis. The British journal of nutrition 2021. PMID 32959735. Read 2026-10-23.
- Costa ES et al. Beneficial effects of green banana biomass consumption in patients with pre-diabetes and type 2 diabetes: a randomised controlled trial. The British journal of nutrition 2019. PMID 30887937. Read 2026-10-23.
- Bendiks ZA et al. Conserved and variable responses of the gut microbiome to resistant starch type 2. Nutrition research (New York, N.Y.) 2020. PMID 32251948. Read 2026-10-23.
- Woh PY et al. Bacillus cereus in rice: A review on food poisoning, antimicrobial resistance, and control measures. Tropical biomedicine 2024. PMID 39548784. Read 2026-10-23.
- NHS. Starchy foods and carbohydrates. Read 2026-10-23.
- Grabitske HA et al. Gastrointestinal effects of low-digestible carbohydrates. Critical reviews in food science and nutrition 2009. PMID 19234944. Read 2026-10-23.