The condition and function of the gastrointestinal tract is essential to our well being. After the respiratory tract, the GI tract constitutes the second largest body surface area, comparable in surface area to a tennis court. During a normal lifetime, about 60 tons of food will pass through this canal.
The human intestinal microflora is highly important to the host for several reasons. Firstly, microflora benefit the host by increasing resistance to new colonization as well as by protecting against the overgrowth of already-present potentially pathogenic organisms. Another function important to the host is the high metabolic activity of the intestinal flora. The extent of this activity has been claimed to be similar to that of the liver. Administration of antimicrobial agents, such as antibiotics, is the most common cause of disruption of the balance of the normal microflora and leads to decreased resistance to colonization ( known clinically as loss of colonisation resistance), and to alterations in the metabolic activities of the intestinal flora.
It is likely that the first scientific assessments of probiotics were made in 1908, based on the work of the Russian Nobel Prize Laureate Elie Metchnikoff. He first hypothesized that a high concentration of lactobacilli in intestinal flora were important for health and longevity in humans. Indeed, we now know that intestinal flora plays an important role in health: stimulating the immune system, protecting the host from invading bacteria and viruses, aiding digestion and assimilation of food. Yet, the importance of these bacteria in the gastro-intestinal (GI) tract has been neglected for a long time, while the focus was merely placed on enteric pathogens and other factors leading to gastrointestinal “disorders”.
The composition of the gastrointestinal flora differs among individuals, and also throughout life within the same individual. Many factors, such as diet or climate, ageing, medications (especially antibiotics), illness, stress, pH, infection, geographic location, race, socioeconomic circumstances, and lifestyle can upset this balance. Interactions of typical intestinal bacteria may also contribute to stabilization or destabilization. A state of balance within the microbial population within the GI tract can be called “eubiosis” while an imbalance is termed “dysbiosis”. For optimum “gut flora balance”, the beneficial bacteria, such as the gram-positive Lactobacilli and Bifidobacteria, should predominate, presenting a barrier to invading organisms. Around 85% of the intestinal microflora in a healthy person should be good bacteria and 15% bad bacteria. The greater the imbalance, the greater the likely symptoms. The use of probiotics may be the most natural, safe and common sense approach for keeping the balance of the intestinal ecosystem.