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   from the issue of March 29, 2007

Milk carbohydrate shows ability to stymie bacterial infection


Certain carbohydrates found naturally in milk can help prevent harmful bacteria from settling in the gastro-intestinal tract and causing disease, according to UNL research.

The carbohydrates, known as galactooligosaccharides or GOS, are structurally similar to the sugars that line cells inside the GI tract and to which bacteria attach, said UNL Food Microbiologist Robert Hutkins. His research showed the bacteria can be "fooled" into attaching instead to the GOS and then be flushed through the intestinal tract without it sticking around.

Harmful bacteria "don't begin to initiate the infection cycle until it's attached to the GI tract," the Institute of Agriculture and Natural Resources scientist said. "It's that initial attachment that we're concerned about."

The galactooligosaccharides reduced the adherence of the bacteria by about 70 percent in the research, Hutkins said.

Oligosaccharides already were known to stimulate growth of healthy bacteria in the gastrointestinal tract, Hutkins noted, but this is the first research to show its potential usefulness as a decoy for the harmful bacteria.

The research was done using enteropathogenic E. coli, which causes diarrheal diseases in children and also in developing countries. Preliminary date suggests the well-known E. coli O157:H7 is similarly affected by the approach, Hutkins said.

Galactooligosaccharides occur naturally in cow and human milk. This may offer partial explanation for why nursed babies don't get as many gastrointestinal infections as formula-fed infants. GOS can be developed into a food ingredient made from milk sugars, which means infant formula manufacturers could add them to their products.

"Their whole goal is to make infant formula as much like human milk as possible, including having many of the positive nutritional properties," Hutkins said.

Galactooligosaccharides already are added to many foods made in Asia and Europe, including dairy foods, granola bars, crackers and breakfast cereals.

The research has been done with tissue cells so far, Hutkins said. He's seeking further funding to test the approach on animals.

The research was featured in an article in the December 2006 journal Infection and Immunity. Other authors were Kari Shoaf, a UNL graduate student; and George L. Mulvey and Glen D. Armstrong of the University of Calgary.



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