Processed food, and modern food preparation methods reduce beneficial bacteria normally ingested from fresh fruits, vegetables, and milk products. Antibiotics do kill germs but they can also wipe out the beneficial microbes we rely upon for digestive health. Chemicals, pollution, and poor diet also wreak havoc on the beneficial bacteria naturally occurring in our bodies. These familiar, even every-day factors take their toll on the health of the microflora and can lead to deficiencies in intestinal function and digestion, immune system response, and resistance to infectious pathogens. By replenishing the proportion of beneficial bacteria in the intestinal flora, probiotics support the body’s ability to address these deficiencies.

In the digestive system, probiotics improve food digestion directly by helping the body to assimilate nutrients, through contributing to the metabolism of bile acids and accelerating their elimination, as well as by producing digestive enzymes. As well, the bacteria in the intestinal flora play a role in metabolising lipids and in breaking down cholesterol. And many beneficial bacteria produce Vitamin K - a very important blood coagulation factor¹.

70% of the body’s immune system response originates in the intestine, and the intestinal flora is made up of as much as 100 trillion bacteria. Because of its direct contact with external invaders capable of inducing infections, the intestine must be able to adequately defend the body. The intestine is very rich in immune system lymphocytes - B cells and T cells that can be found under the mucous membrane lining the intestine. A person's normal bacterial flora also plays a part in the immune responses via the epithelial cells of the intestine that make up the mucous membrane. Consumption of beneficial bacteria reinforces intestinal mucous membrane immunity as well as the body's global immunity, while stimulating phagocytic activity and increasing the body’s production of antibodies and lymphocytes.

The good bacteria that comprise the intestinal flora are the first line of defence against intruders. They adhere to the intestinal wall and reinforce the physical barrier against pathogens. They compete with them for a spot to adhere on the intestinal wall and for the nutrients found there. They also produce natural antimicrobial substances called bacteriocins. These two methods of defence discourage the implantation, growth, and survival of pathogens. The production of organic acids, hydrogen peroxide, and bacteriocins by lactic bacteria inhibits pathogenic activity. The organic acids produced by lactic bacteria regulate the intestinal pH to maintain it at a level that reduces the growth of infectious agents.

• 1. Resta SC. Effects of probiotics and commensals on intestinal epithelial physiology: implications for nutrient handling. J Physiol. 2009. 587:4169-4174.