When most people think about fibre, they think about digestion. But one type of fibre does something even more remarkable—it feeds the beneficial bacteria living in your gut.

This special type of carbohydrate is called resistant starch. Instead of being digested in the small intestine, it travels to the large intestine where it becomes food for your gut microbiome. As your gut bacteria ferment resistant starch, they produce beneficial compounds called short-chain fatty acids (SCFAs), including butyrate, which help support digestive health, metabolism, immune function and overall wellbeing.

The good news? Resistant starch is easy to include in your everyday diet.

What Is Resistant Starch?

Resistant starch is a carbohydrate that “resists” digestion. Rather than being absorbed for energy like most starches, it reaches the colon where it nourishes beneficial gut bacteria.

During fermentation, these bacteria produce important SCFAs, including:

• Butyrate – supports the cells lining the colon and helps maintain gut barrier health.
• Propionate – plays a role in healthy glucose metabolism.
• Acetate – the most abundant SCFA, involved in energy and fat metabolism.

Instead of feeding you directly, resistant starch feeds the beneficial bacteria that support your health.

Why Is Resistant Starch Good for You?

Research suggests resistant starch may help:

• Support a healthy gut microbiome
• Increase the production of beneficial SCFAs such as butyrate
• Support healthy blood sugar levels when included in a balanced diet
• Help you feel fuller for longer
• Support digestive and metabolic health as you age

While no single food is a magic solution, regularly including resistant starch-rich foods can be one simple way to support long-term gut health.

Want to Learn More About Postbiotics?

As your gut bacteria ferment resistant starch, they produce beneficial compounds known as postbiotics, including butyrate, acetate and propionate.

These compounds help support the gut lining, immune function and metabolism.

Want to learn more? Read our article “What Are Postbiotics? Understanding Butyrate and Your Gut Microbiome” to learn how these beneficial compounds are produced and why they’re becoming one of the most exciting areas of gut health research.

Foods Rich in Resistant Starch

Adding resistant starch to your diet doesn’t have to be complicated.

Great sources include:

• Green bananas
• Green banana flour
• Cooked and cooled potatoes
• Lentils
• Beans
• Chickpeas
• Rolled oats

One interesting fact is that cooling potatoes or rice after cooking increases their resistant starch content through a process called retrogradation.

Why We Love Green Banana Flour

Green banana flour is made from unripe bananas before much of the starch has converted into natural sugar, making it naturally rich in resistant starch.

It’s also:

• Naturally gluten-free
• Mild in flavour
• Easy to add to smoothies, pancakes and waffles
• A simple way to boost resistant starch in your baking

For most recipes, replace about 20–25% of the flour with green banana flour rather than substituting it completely.

Gut-Friendly Resistant Starch Waffles

Ingredients

• 1½ cups rolled oats
• ½ cup green banana flour
• 1 ripe banana
• 2 cups unsweetened almond or oat milk
• 2 tbsp chia seeds
• 1 tsp vanilla
• 1 tsp baking powder
• 1 tsp cinnamon
• Pinch of sea salt

Instructions

1. Blend all ingredients until smooth.
2. Let the batter rest for 5-10 minutes.
3. Cook in a preheated waffle maker until golden.
4. Top with fresh berries and chia berry jam.

Quick Chia Berry Jam

Ingredients

• 2 cups frozen mixed berries
• 2 tbsp chia seeds
• 1 tsp lemon juice
• Optional: 1–2 tsp maple syrup

Heat the berries until softened, mash lightly, stir in the chia seeds and lemon juice, then allow the mixture to cool and thicken for about 20 minutes.

More Easy Ways to Add Resistant Starch

Try:

• Adding green banana flour to smoothies
• Making overnight oats
• Enjoying potato salad made with cooled potatoes
• Adding beans or lentils to soups and salads

Small, consistent changes often make the biggest difference.

Why Gut Microbiome Testing Can Help

Everyone’s gut microbiome is unique, which means people don’t always respond to the same foods in the same way.

Comprehensive gut microbiome testing can provide insights into:

• Microbial diversity
• Beneficial and opportunistic bacteria
• Functional pathways related to short-chain fatty acid production
• The abundance of key butyrate-producing bacteria

Tests such as MapmyBiome can provide insights into the abundance of beneficial bacteria involved in short-chain fatty acid production, helping you and your healthcare practitioner personalize nutrition and lifestyle recommendations based on your unique gut microbiome.

The Bottom Line

Resistant starch is much more than another nutrition trend.

By feeding the beneficial bacteria in your gut, it supports the production of important compounds like butyrate that contribute to digestive health, metabolism and overall wellbeing.

Simple foods such as green banana flour, oats, legumes, beans and cooked-and-cooled potatoes can help nourish your gut microbiome and are easy additions to everyday meals.

For even more ways to support your gut health, be sure to read our related articles:

• What Are Postbiotics? Understanding Butyrate and Your Gut Microbiome
• Prebiotics & Probiotics: What’s the Difference and Why Your Gut Needs Both

Together, these articles will help you better understand how nutrition and your gut microbiome work together to support long-term health.

Frequently Asked Questions

Is resistant starch the same as fibre?

It behaves much like dietary fibre because it resists digestion and is fermented by beneficial gut bacteria.

Is green banana flour gluten-free?

Yes. Green banana flour is naturally gluten-free and works well in many baking recipes.

Can resistant starch help support blood sugar?

Research suggests resistant starch may help support healthy blood sugar and insulin sensitivity when included as part of a balanced eating pattern.

Does cooking affect resistant starch?

Yes. Cooling foods such as potatoes and rice after cooking increases their resistant starch content.

References

• Birt DF, et al. Resistant Starch: Promise for Improving Human Health. Advances in Nutrition. 2013.
• Koh A, et al. From Dietary Fibre to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Cell. 2016.
• Louis P, Flint HJ. Formation of Propionate and Butyrate by the Human Colonic Microbiota. Environmental Microbiology. 2017.
• Health Canada. Dietary Reference Intakes for Fibre.