In a new study from the Norwegian University of Life Sciences published in the Journal of Dairy Science it was found that some probiotic bacteria strains survive better into the intestinal tract when consumed with fermented milk. It is no surprise that such a study should find its way into a dairy journal but it does highlight a crucial factor when it comes to the popular use of probiotics; how much of a probiotic actually gets to where it is needed? This is vital for product efficacy of course and some cutting edge methodology is being used to establish exactly what happens with probiotics once they are in the digestive tract.
Probiotic bacteria are increasingly used in food and pharmaceutical applications to balance disturbed intestinal microflora and related dysfunction of the human gastrointestinal tract. Lactobacillus acidophilus and Bifidobacterium spp. have been reported to be beneficial probiotic organisms that provide excellent therapeutic benefits. There is some evidence that merely the DNA of these bacteria is enough to exert some beneficial effects but for the most part the bacteria need to arrive alive in order to confer their benefits.
The biological activity of probiotic bacteria is due in part to their ability to attach to cells lining the intestines. This inhibits the binding of pathogens by a process of competitive exclusion. Attachment of probiotic bacteria to cell surface receptors of intestinal cells also causes the release of chemicals caused cytokines that turn on your immune system. Probiotic bacteria also produce lactic acid and bacteriocins that stop bad bacteria and other harmful organisms from growing. Production of butyric acid by some probiotic bacteria also beneficially affects the turnover of cells in the wall of the large intestine as well as neutralising the activity of dietary carcinogens, such as nitrosamines, that are generated by the metabolic activity of bacteria in people consuming a high-protein diet.
Bifidobacteria and Lactobacilli are chief among the probiotic species and their survival during passage through the human gut has been investigated intensely in recent years. Studies on diarrhoea in both adults and infants have shown that probiotics are beneficial and that they survive in sufficient numbers to affect gut microbial metabolism. Survival rates have been estimated at between 20 and 40 per cent for selected strains, the main obstacles to survival being stomach acidity and the action of bile salts in the small the small intestine.
Probiotic administration usually results in an increase in faecal counts of bifidobacteria and lactobacilli, a decrease in faecal pH, and a decline in bacterial enzymes that are associated with the development of colon cancer.
Measuring what happens at the end of the digestive process gives some indication of the effectiveness of probiotic products and that survival does occur to some degree. The dream though would be to find out exactly what happens to probiotics in the stomach, small intestine, and colon. Unfortunately, people tend to object to having the contents of their digestive tract extracted; it’s messy and it disturbs the flow of your conversation. So an emerging field of research is using a simulated version of the digestive process to establish exactly what happens to probiotics throughout the digestive tract.
SHIME stands for “Simulator of the Human Intestinal Microbial Ecosystemâ€. This laboratory technique was created to simulate the activities and conditions found in the stomach, small intestines, and large intestines. It is a dynamic model of the digestive tract that simulates the acid and pepsin from the stomach, small intestine enzymes, and then the conditions of three phases of the large intestine. This enables researchers to monitor the quantity of bacteria that survive the journey to the large intestines.
SHIME studies have shown that the bacterium Lactobacillus reuteri alters bile salt activity in the small intestine. Changes in bile salt circulation can impact cholesterol levels and animal based studies have shown that this probiotic does in fact alter cholesterol levels favourably.
The theoretical benefits of probiotics are huge. The evidence is that those benefits can transfer into real world situations and laboratory studies are also confirming that probiotics really do shime.
