Functional foods offer hope for fighting infections

Upset stomachs and gut diseases are a common problem amongst our increasingly elderly population, but now help may be on hand using friendly bacteria isolated from the intestines of healthy elderly individuals, according to scientists speaking today (Wednesday, 08 September 2004) at the Society for General Microbiology’s 155th Meeting at Trinity College Dublin.

Giving elderly patients antibiotics often causes nearly as many problems as it cures, by wiping out the protective bacteria that live in their intestines, and allowing diarrhoea causing bacteria to grow, according to researchers from the School of Food Biosciences at the University of Reading.

The scientists are investigating the claims of friendly ‘probiotic’ bacteria, which are supposed to slow down dangerous bacteria and help replace them with good ones, and if this works, which types of bacteria work best. Once identified and properly tested, friendly bacteria could be incorporated into functional foods to help boost elderly patients’ defences when in hospital or nursing care.

“We found seven lactobacilli, from the same family as the ones used to make yoghurt, in the intestines of healthy elderly individuals. We then looked at their ability to prevent the growth of particularly nasty bacteria called Clostridium difficile which frequently causes upset stomachs after antibiotic use,” says Kirstie Manderson of Reading University. “We needed to know if they could survive being passed through the stomach to the intestine, live there in spite of antibiotic treatment for C. difficile infection, and thrive in the competitive environment of the human large intestine.”

One of the candidates, Lactobacillus plantarum, survived all the tests and showed that it could slow down the growth of C. difficile in laboratory tests. Now the scientists hope that it will help in the battle against antibiotic-resistant bacteria.

“Antibiotic-resistant bacteria are becoming such a problem, especially in the elderly, that we need to find new ways to fight them – and probiotics, these friendly bacteria, may be one of them,” says Kirstie Manderson. “We cannot continue to rely on antibiotics alone.”

Foods containing probiotic bacteria could be fed as a preventative supplement to elderly patients who are hospitalised or receiving long term nursing care, to help cut the number of cases of diarrhoea. The foods could also be given whenever people are receiving antibiotic treatment, to help maintain the balance of friendly bacteria in their guts.

“We have shown that we can target probiotic bacteria to specific population groups who are vulnerable to some diseases. We could extend the approach to other groups such as infants,” says Kirstie Manderson. “The rational and targeted use of these functional foods might be more effective at reducing the risk of infection than eating more heavily processed products, or using increasing amounts of pharmaceuticals, with the associated risk of spreading antibiotic resistant strains of bacteria.”