Resistant Starch Foods: What to Eat and How to Prepare Them
Resistant starch is found in pulses, whole grains, firm green bananas, raw oats and in potatoes, rice and pasta that have been cooked and then cooled. It acts like fibre: it escapes digestion in the small intestine and is fermented in the large bowel. This guide lists the foods, shows how preparation changes the amount, and explains who should be cautious, because for some people more resistant starch makes symptoms worse.
TL;DR
- The most reliable sources are beans, lentils, chickpeas, whole grains, raw oats and under-ripe bananas.
- Cooking and then cooling potatoes, rice or pasta raises resistant starch, but only moderately. It is a tweak, not a trick.
- Cooled rice needs strict food safety: chill it quickly and eat it within 24 hours.
- If you have IBS, IBD or a sensitive gut, more resistant starch can cause gas, bloating and pain. Go slowly and ask a professional first.
- The best amount and the best foods depend on you, which is why a generic list only takes you so far.
Table of Contents
- What resistant starch is, and the five types
- A practical list of resistant starch foods
- How cooking and cooling change the amount
- How much do you need, and what might it do?
- Who should be careful
- How to increase resistant starch without upsetting your gut
- Our perspective
- Get a plan built around your digestion
- FAQ
- Sources
What resistant starch is, and the five types
Most starch is broken down into glucose in the small intestine. Resistant starch is the part that is not. It reaches the colon, where gut bacteria ferment it. The University of Florida IFAS groups it into five types by origin and processing:
| Type | What it is | Typical foods |
|---|---|---|
| RS1 | Starch trapped inside plant cell walls | Whole grains, seeds, pulses |
| RS2 | Naturally resistant because of its crystal structure | Raw potato, green bananas, high-amylose maize |
| RS3 | Formed when cooked starch cools (retrogradation) | Cooled rice, pasta, potatoes |
| RS4 | Chemically modified | Some processed foods |
| RS5 | Amylose-lipid complex | Some processed foods |
The types matter. A systematic review from Imperial College London of people with type 2 diabetes or prediabetes found that RS1 and RS2 currently have better evidence for lowering the blood glucose response than RS3, RS4 or RS5.
A practical list of resistant starch foods
Use this as a starting point for the shopping list.
Naturally rich, no tricks needed
- Lentils, chickpeas, kidney beans, butter beans and other pulses (RS1)
- Whole grains such as barley, and wholegrain bread with visible grains and seeds (RS1)
- Raw rolled oats, as in overnight oats (RS2)
- Green or just-yellow bananas and plantains (RS2)
Increased by cooking and cooling
- Potatoes, including new potatoes in a salad
- Rice
- Pasta
- Oats that have been cooked and then chilled
Ripeness and cooking matter. Oats, green bananas and plantains lose some of their resistant starch when cooked, and bananas lose it as they ripen. A soft, spotty banana is a poor source, whereas a firm, slightly green one is a better one.
How cooking and cooling change the amount
When starchy food cools, the starch molecules rearrange into tighter structures that resist digestion. Harvard Health reports that a cooked and chilled russet potato holds about 4.3 g of resistant starch per 100 g, against 3.1 g when served hot. That is roughly 39% more, but in absolute terms it is a small gain in a food that is still mostly digestible starch. Cooled potato salad is not a zero-calorie carbohydrate.
Reheating after cooling generally keeps the resistant starch that has formed, so chilled-then-warmed potatoes still count.
Rice: food safety comes first
Cooled rice can carry Bacillus cereus, a bacterium that causes food poisoning. If you cool rice for its resistant starch, cool it fast (within about an hour), keep it in the fridge, and reheat it until steaming hot, all within 24 hours. The Guy’s and St Thomas’ NHS Foundation Trust food safety advice explains safe storage, and many NHS trusts tell people with weakened immune systems, such as those having chemotherapy, to avoid reheating rice altogether. If that is you, skip this technique and rely on pulses and whole grains instead.
Other factors that lower the amount
Milling, high-heat cooking and fermentation can all deplete resistant starch, as a narrative review in Frontiers in Nutrition sets out. That is one reason finely milled white bread is a weaker source than a dense wholegrain loaf. If you are curious about the chemistry of the role of yeast in fermentation, it helps explain why long-fermented or heavily processed foods behave differently from simply cooked ones.
How much do you need, and what might it do?
There is no official UK intake target for resistant starch. Studies have used anything from 6 to 40 g a day. A meta-analysis of 19 randomised trials in the British Journal of Nutrition found that long-term intake modestly lowered fasting blood glucose, by 0.31 mmol/L on average. Those were research doses, often from supplements, which are hard to match with food alone, so do not expect a dramatic change from a bowl of cold potato salad.
If blood sugar is your concern, resistant starch is one part of a wider pattern. Our guides to the prediabetes diet and the insulin resistance diet show where it fits.
Who should be careful
Sensitive bowels, IBS or IBD. Fermentation of resistant starch in the colon produces gas. Cambridge University Hospitals notes this can aggravate bloating, pain and diarrhoea, and a lower-resistant-starch approach is sometimes used for a trial period. If you have a diagnosed bowel condition, speak to your GP, gastroenterologist or a registered dietitian or nutritionist before raising your intake.
Pregnancy. Do not cut carbohydrates or chase resistant starch. Spread starchy carbohydrates evenly through the day and pair them with protein, as NHS patient information on gestational diabetes advises. Our gestational diabetes diet guide goes through this in practice.
Weakened immunity. Avoid reheating rice, as above.
How to increase resistant starch without upsetting your gut
- Start small. Add one change at a time, for instance half a tin of lentils in a stew.
- Build up over two to three weeks. A sudden jump is what causes wind and bloating.
- Drink enough water as fibre intake rises.
- Swap rather than add. Use barley for some of the rice, or choose a wholegrain bread.
- Cook ahead for safety as well as starch. Cool potatoes and pasta quickly, store them covered in the fridge and eat them within the safe window.
- Keep a short food and symptom diary for two weeks, so you can see what helps and what does not.
Our perspective
A list of foods is the easy part. What we see with clients is that the hard part is making the advice fit one person’s gut, medication, schedule and appetite. Someone with prediabetes and a robust digestion may do well with lentils and cooled potatoes. Someone with IBS and fatigue may need the opposite for a while. Clients who have tried several diets without lasting change often have a root cause that a general fibre message never touches.
That is why we work in programmes, not single appointments. We look at your symptoms, routine and, where appropriate, functional laboratory results, then adjust the plan as your body responds. We would rather you eat a modest amount of resistant starch comfortably than follow a trend that leaves you bloated.
— Irina
Get a plan built around your digestion
If you want to know which of these foods suit you, we can help. Our nutrition programmes start with a one and a half hour initial consultation plus written personalised recommendations for £150, and a follow-up within eight weeks is £120. Twelve weeks of dedicated support is £250. See the full details on our prices page, or read about what our services include. Our practitioners hold an MSc in Nutrition and are BANT and CNHC registered.
FAQ
Can rice become a resistant starch?
Yes. Cooking and then cooling rice forms RS3 through retrogradation. Because of the Bacillus cereus risk, cool it within about an hour, refrigerate it and eat it within 24 hours, reheating until steaming hot.
Does reheating cold potatoes destroy resistant starch?
Generally no. Reheating after cooling largely keeps the resistant starch that formed. The gain from cooling is moderate anyway, about 4.3 g per 100 g chilled against 3.1 g hot in a russet potato.
What are the best sources of resistant starch?
Pulses, whole grains, raw oats and firm green bananas are the most dependable, because they contain resistant starch before any special preparation. Cooled potatoes, pasta and rice add a smaller extra amount.
Is resistant starch safe for IBS?
Not always. It ferments in the colon and can increase gas, bloating and pain in sensitive bowels. If you have IBS or IBD, take advice from your GP or a registered nutrition professional before increasing it.
Sources
- University of Florida IFAS: Resistant Starch, what it is and how to add more
- Imperial College London systematic review on resistant starch types (PubMed)
- Harvard Health: Resistant starch
- Guy’s and St Thomas’ NHS Foundation Trust: Food safety
- Frontiers in Nutrition: Harnessing the power of resistant starch
- British Journal of Nutrition: Effects of resistant starch on glycaemic control
- Cambridge University Hospitals: Resistant starch
- NHS patient information on gestational diabetes