Resistant starch, food structure and the gut microbiota: new insights Dr. Fred Warren, Research Leader

What is starch? And what makes it resistant?

• Starch is a key component in the human diet, and our main source of energy

• It is a complex carbohydrate , which is broken down during digestion to release glucose

What is starch? And what makes it resistant?

• A proportion escapes digestion a reaches the colon, where it is available to be fermented by gut bacteria

• Bacterial fermentation of carbohydrate has many health benefits

http://www.cpe.sk/ka-izvairities-no-gremosanas-sistemas-traucejumiem/

• Not all of the starch that we eat gets digested in our small intestine

Why the resurgence of interest in resistant starch?

• Technological advances in the last ~5 years have shed new light on the importance of microbes in our gut

psychneuro.wordpress.com

Do we know what makes starch resistant?

RS type 1: Entrapped starch

Edwards et al. Food & Function 2015

www.harvard-health.edu

Do we know what makes starch resistant?

RS type 2: Native starch

Roder et al. Food Chemistry 2009

www.psu.edu

Do we know what makes starch resistant?

RS type 3: Retrograded starch

www.food-network.com

Roder et al. Food Chemistry 2009

Do we know what makes starch resistant?

RS type 4: Chemically modified starch

www.cbhcn.com Chen et al. RSC advances 2015

Resistant starch as an ingredient isn’t always the best idea…

How much resistant starch is there in my food?

• Labelling of resistant starch is a major challenge

• In the UK resistant starch isn’t included in labelling, in the US it is included as dietary fibre

Measuring resistant starch is a major challenge

• For labelling, we need a standardised, reliable method to measure resistant starch

• Unfortunately, measuring resistant starch is a moving target

A combination of lab based assays and ileostomy patients offers possibilities

How can we manipulate food structure to increase resistant starch?

Edwards et al. AJCN 2015

• Exploiting natural plant food structures

How can we manipulate food structure to increase resistant starch?

Edwards et al. AJCN 2015

• Exploiting natural plant food structures

How can we manipulate food structure to increase resistant starch?

• Manipulating starch structure at the molecular level

www.csiro.au

Are all resistant starches fermented in the same way in our large intestines?

Are all resistant starches fermented in the same way in our large intestines?

Are all resistant starches fermented in the same way in our large intestines?

Are all resistant starches fermented in the same way in our large intestines?

Are all resistant starches fermented in the same way in our large intestines?

Conclusions

• Measuring, and even defining, resistant starch is a huge challenge

• Resistant starch exists in many foods, and can be increased with small tweaks to processing/ingredients

• Not all resistant starches have the same effects in our colons- and this is an area we are only just beginning to understand