Small intestine microflora: a key to your health

HOW CAN PROBIOTICS (LACTO & BIFIDOBACTERIA) ENHANCE MY IMMUNE SYSTEM AND MY HEALTH?

Disturbances in the composition of the intestinal microbiota (a collective name for bacteria that inhabit the gastrointestinal tract) lead to an imbalance between beneficial and harmful bacteria and are associated with several immunological disorders.

Taking supplements that contain probiotics (beneficial bacteria) may help correct alterations in the composition of intestinal microbiota. Communication between intestinal microbiota and the human body is mediated by multiple regulatory mechanisms.

Bacteria may directly interact with intestinal epithelial or immune cells and can also produce bioactive compounds that act as immune modulators. Notably, approximately 70% of immune system cells are located in the gastrointestinal tract. Probiotics are known to have beneficial effects on immunity, both at the molecular and cellular levels. For example, two studies, one conducted in Canada and the other in New Zealand, found that probiotics increase the production of interferon-α (which plays a role in protection against viral infections) in healthy elderly people but reduce the production of a proinflammatory cytokine tumor necrosis factor (TNF)-α in the gastrointestinal tract. The ability of microbiota to regulate human immunity is illustrated by a study that involved healthy volunteers and found that intake of several species of bacteria that normally live in the intestines and are considered beneficial resulted in changes in the expression of genes involved in the control of immunity.

Some probiotics increase the serum level of the anti-inflammatory cytokine IL-10. Thus, probiotics would be expected to boost the innate immune response against viral infections and at the same time have an anti-inflammatory effect. A number of studies have also documented the ability of probiotics to stimulate the production of immunoglobulin A (IgA), which plays a critical role in mucosal immunity. Probiotics were also reported to enhance the bactericidal activity of leukocytes and to affect the Th1/Th2 balance. Th1 cells produce proinflammatory cytokines (including TNF-α mentioned above) involved in responses to bacterial and protozoan pathogens, and are also involved in inflammatory autoimmune disorders, whereas Th2 cells stimulate production of antibodies against parasites such as worms, and are also involved in allergies. Different probiotics have been shown to selectively shift the balance towards Th1 or Th2 responses, and may sometimes stimulate both.