Although the exact mechanism by which these bacteria do this is not known, there have been a number of laboratory tests that indicate that certain strains produce hydrogen peroxide, which functions as a virus killer. In her book Probiotics, Nature's Internal Healers, Natasha Trenev documents several studies in which friendly bacteria were used to inhibit the herpesvirus. One of the reasons for this may be because cancer-causing substances are produced in the body from the nitrates used in the curing of luncheon meats. Friendly bacteria have the ability to neutralize nitrates. Some strains have the ability to alter enzymes that turn a potentially carcinogenic agent into a carcinogenic agent.
Some strains have the ability to suppress some tumor activity.
Lactobacilli Lactobacilli are one of the most important types of friendly bacteria found in the digestive tract. They play a key role in producing fermented milk, yogurt, and cheeses. His investigation of this led him to diet, yogurt, and lactobacilli. His work was the first to prove that lactobacilli could transform milk sugar into lactic acid. Metchnikoff also hypothesized that this acidity would provide a hostile environment for unfriendly bacteria.