British scientists have thatgut feeling

A desktop computer-size model of the human stomach is so sophisticated it can even vomit


Sun, Nov 12, 2006 - Page 19

British scientists have built what they say is the world's first artificial stomach: a shiny, high-tech box that physically simulates human digestion.

Constructed from sophisticated plastics and metals able to withstand the corrosive acids and enzymes found in the human gut, the device may ultimately help in the development of super-nutrients, such as obesity-fighting foods that could fool the stomach into thinking it is full.

"There have been lots of jam-jar models of digestion before,'' said Martin Wickham of Norwich's Institute of Food Research, the artificial gut's chief designer, referring to the beakers of enzymes typically used to approximate the chemical reactions in the stomach.

Wickham's patented artificial gut is a two-part model, and is slightly larger than the size of a desktop computer. The top half is a cylinder with a blue funnel, into which food is poured. This is where the food, stomach acids and digestive enzymes are mixed. Once this hydration process is finished, the food gets crunched underneath in a silver metal tube encased in a dark, transparent box. In a real human stomach, the food would then be absorbed by the human body.

Software sets the parameters of the artificial gut — how long food remains in a particular part of the stomach, predicted hormone responses at various stages, and whether it is an infant or adult gut.

Unlike previous gut models, Wickham's model incorporates the physiological elements of digestion, including the stomach contractions that break up food and move it along the assembly line of human digestion.

The artificial gut is already attracting commercial attention.

One company wants to use it to test whether a biscuit can release a specific nutrient in the small intestine. Another group wants to determine if soil contaminants, which could potentially be swallowed by children playing outside, get absorbed by the human body.

The model gut's focus on the physical and chemical reactions that take place in the stomach promises to provide a more detailed understanding of food structure and its impact on digestion.

"This is an important tool that will allow us to understand what happens in the gut, which has essentially been like a black box,'' said Peter Ellis, a biochemistry expert at King's College in London, who was not connected to the project.

Other artificial stomach models have largely neglected the connection between food structure and digestion, according to Ellis.

"This model is important because it gets the science of digestion right," he said.

By understanding how food gets processed in the gut, and in which part of the stomach nutrients get absorbed, researchers may ultimately be able to develop foods designed to manipulate the digestive process, a strategy that would have broad implications for public health.

For instance, knowing how quickly glucose gets absorbed into the bloodstream would potentially help treat diabetes.

"Our knowledge of what actually happens in the gut is still very rudimentary," said Wickham, "but we hope that this model can help fill in some of the blanks."

Some experts say any artificial gut has inherent limitations.

"The stomach is an extraordinarily complex organ, so you cannot create a model that will undertake all of these functions," said Stephen Bloom, head of metabolic medicine at Imperial College in London, who was not involved in the project.

Still, Bloom said that looking at issues such as the breakdown of food and the role of enzymes in a model stomach is valuable.

"There are a number of questions that are very difficult to study in real life that could more easily be answered in the laboratory," he said, explaining that using human volunteers to collect information about digestion is usually a costly and uncomfortable process.

With a capacity about half the size of an actual stomach, the artificial gut can "eat'' roughly 600 milliliters of food, or a normal portion of fish and chips. To date, the most substantial meal it's enjoyed is vegetable soup.

"It's so realistic that it can even vomit," adds Wickham.

The model gut, which was publicly funded, was built at a cost of approximately US$1.8 million. Wickham and his colleagues are currently negotiating with about a dozen companies regarding future projects for the gut.