McMaster researcher uncovers secrets of excrement

A team of McMaster researchers has solved a few of the many mysteries surrounding poop.

McMaster University gastroenterology scientist Jan Huizinga and his team made a discovery that has uncovered some of the mysteries behind movement in the intestines and nutrient absorption.

For many years now, scientists have been aware of how food moves through the digestive tract. Pacemaker cells in the intestine create a beat, much like a heartbeat, that moves food forward.

But your food does not make a direct trip through the intestine – it stops and mixes together so that essential nutrients can be absorbed into our bodies. In order to stop and mix food together to absorb nutrients, the beat of the pacemaker cells has to be interrupted.

Before Huizinga’s discovery, scientists believed that the nervous system of the digestive tract was able to interrupt the beat of the pacemaker cells so that food can stop and nutrients can be absorbed.

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“The intestine has its own nervous system, just like in the brain,” Huizinga said. “Everyone, including myself, always assumed that the nervous system created the motor pattern [for absorption],” said Huizinga.

One day, during an experiment, Huizinga and his colleagues discovered that when they blocked the activity of the nervous system, nutrients were still absorbed.

“We had to change completely every protocol, every idea, every hypothesis,” Huizinga said. “If it is not the nervous system, what is it?”

Two years since this experiment, Huizinga and his team have discovered it is the nutrients themselves and natural intestinal bacteria that interrupt the beat of the pacemaker and allow for absorption.

When we eat certain nutrients, they induce a second pacemaker that sends an electrical signal, interrupting the first pacemaker. When the first pacemaker is interrupted, movement stops and nutrients can be absorbed.

“Now we know the motor patterns involved, we can diagnose patients better by actually measuring the intestinal movements and seeing if the right movements are there,” explained Huizinga.

This can be extremely helpful for patients who have problems with digestion, including chronic diarrhea, constipation or irritable bowel syndrome.

This discovery has also opened the door for future research that looks at which nutrients are best for digestion, or what drugs can be developed to supplement these nutrients.

The study was completed in partnership with Wuhan University in China and with assistance from colleagues from the University of Toronto.

Funding was provided by the Canadian Institutes of Health Research and the National Natural Science Foundation of China. Additional support was given by the Canadian Association of Gastroenterology, Hamilton Health Sciences, and the Ontario Government. The paper was published in Nature Communications on February 24, 2014.