CSIRO scientists in Adelaide have discovered that the kind of 'resistant starch' now being used to make environmentally-friendly packaging can also boost health-giving bacteria in the human bowel and may one day help save thousands of Australian lives.
Dr David Topping, from the CSIRO Division of Human Nutrition, today announced the results of new research which show that resistant starch promotes the growth of bifido bacteria in the gut æ the same kind of beneficial bacteria which are included in many commercial yoghurt brands.
Dr Topping's tongue-in-cheek prediction is that future Australians could wrap their sandwiches in plastic made from plant-based resistant starch æ then eat the wrapper instead of throwing it away.
The CSIRO's latest research results, showing how resistant starch changes the mix of bacteria beneficially in the human bowel, will be published later this year in the international Journal of Nutrition.
Dr Topping says resistant starch is now shaping up as a very important dietary protection against cancer and other bowel diseases, which are responsible for over four per cent of all Australian deaths æ and kill more than 4,300 individuals each year.
Resistant starch is so named because it resists being digested in the stomach and lower intestine. Instead it travels right through the digestive tract to arrive largely intact in the large intestine (or colon), where it had a number of significant health benefits.
Dr Topping says scientists did not at first fully appreciate why resistant starch was so good for the colon. However, earlier research in pigs had shown it dramatically promoted the growth of beneficial bacteria, boosting
their numbers tenfold. In the process it protected the bowel against cancer and other diseases, including diarrhoea and constipation. Results in human research are equally promising.
Modern Australians eat only about half as much starch as they need, largely because modern diets exclude it. In pre-industrial societies, where people ate far more starch, bowel cancers and other colon diseases were virtually unknown.
Dr Topping says resistant starch may soon have another great benefit: researchers are studying ways to use it as a "taxi" to covey other beneficial substances into the lower bowel.
For example chemicals or even bacteria which help protect against cancer and other diseases could be encased in the resistant starch, which will then carry them safely through the digestive tract to where they are needed. Without the protection of the starch, they would probably be digested along the way.
He says that growing recognition of the importance of resistant starch in human diets marked a major shift in scientific thinking.
Until very recently most scientists had believed it was the fibre content of foods which gave people protection against bowel cancer. However, now it appeared resistant starch æ not fibre æ was responsible.
Dr Topping observes some of the new plant-based plastics now coming onto the market are made mostly of resistant starch æ although he does not advise anyone to eat them in their present form. Nevertheless, one day the idea of "edible plastics" may not be as strange as it sounds.
Journal
Journal of Nutrition