REVIEW – March 2005

The effect of lactic acid bacteria on human health


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During the last decade, increasing evidence has been found to prove that the risk of catching immune-mediated illnesses is largely induced by changes in the micro-flora of the ambient outdoor environment and, consequently, by the changes in the intestinal tract of a person.

More research was conducted to investigate the lactic acid bacteria at the beginning of the nineteenth century, although the positive effects of lactic acid bacteria on food preservation and on improvement of general health were known earlier.

The genus Lactobacillus is a species of the widely known and widespread non-sporulating gram-positive rod-shaped lactic bacteria. One of the representatives of the species is the probiotic strain Lactobacillus rhamnosus GG (LGG), isolated from the microflora of a healthy person’s intestine, in the early 1980s.

The positive features of LGG, affecting human health, have been proved with more than 260 clinical investigations.

When an antigen, a microbe or a food sub-stance, makes contact with the surface of the small intestine, it will be presented to T-lymphocytes, which will activate, with the mediation of cytokines IL-6 and TGB-β and B-lymphocytes to produce antibodies against antigens. To fight the antigens found in the intestine, IgA class antigens are formed the task of which is to bind viruses and bacteria, to prevent their access to intestinal cells and to inactivate the toxins of the bacteria. Lymphocytes that secrete IL-4 cytokine increase the production of the antibodies of the IgE class against parasites and food substances.

Clinical research on the Lactobacillus rhamnosus strains has shown that the probiotic lactic bacterium stimulates the production of the Th1 type cytokines IL-12, IL-18, and IFN-β, which prevent Th2 immune response and hence have the effect of reducing IgE production. It has been discovered that LGG-1has a feature which helps reduce the risk of developing allergic illnesses, alleviate the symptoms of atopic skin inflammation in infants and at the same time reduces the risk of developing respiratory diseases.

Regarding the ability of the lactic bacteria to attach firmly onto the epithelial cells of the intestinal mucous membrane, to produce anti-microbial compounds which prevent the growth of harmful microbes, and to increase the production of mucilaginous substance, the probiotics shorten the period of infectious diarrhoea and reduces the risk of developing infections of the digestive tract.

Presence of lactic acid bacteria balances the microflora of the intestine and reduces the effects of antibiotics and the effects of digestive tract diseases such as gases, stomach ache, diarrhoea, or constipation, induced by various illnesses (e.g. irritable bowel syndrome, chronic infectious intestinal illnesses, malignant processes).

One of the discoverers of the Lactobacillus rhamnosus GG, Prof Sherwood Gorbach, celebrated his 70th birthday only recently. To the question ”What do you think is the future for probiotics?” Prof Gorbach answered, ” Certainly, various new therapeutic fields of use.”

Hopefully, we can use more of similar probiotics that would help avoid allergies and improve the quality of life of patients.