Human beings eat food to derive energy and nutrition for the purpose of sustenance, growth and reproduction. In fact, this is true for all the living systems such as plants, microorganisms and animals. In the case of animals (including humans), food is partially digested in the alimentary canal, mouth and stomach and finally in the intestine, where the partially digested food is ultimately metabolized by billions of microorganisms working simultaneously and synergistically. It has been said that there are more bacteria in one person at one time than there are people on this earth. Fortunately, however, less than one percent of all the known types of microorganisms are undesirable or pathogenic.

A healthy intestine is one which maintains a critical balance between various groups of these bacteria such as lactobacilli, streptococci, clostridia, coliform and bacteroides. Any suboptimal or unhealthy conditions like stress, onset of disease, ingestion of antibiotics and/or other medicines, such as antacid remedies (the purple pill), improper food and rest, and harmful environmental conditions may endanger this fine balance in the intestinal flora, resulting in the reduction of the friendly or beneficial bacteria like lactobacilli and bifidobacteria in the gut.

For centuries, lactic acid bacteria have been used for the preservation of food for human consumption. It has been well documented that certain types of lactobacilli and bifidobacteria are essential or desirable for optimal health. Eli Metchnikoff was perhaps the first probiotic researcher as he concluded in 1908 that the long life span of residents of the Balkan Islands was due to the ingestion of large quantities of lactobacilli and other lactic organisms through fermented foods, which inhibit pathogens and detoxify the system.

For nearly a hundred years, research has been conducted on lactobacillic cultures and many amazing facts about their probiotic nature have been established. ("Probiotic" refers to those microorganisms that can prevent or reduce the effect of an infection caused by a pathogenic organism.) In fact, such probiotic aspects have been consequently related to the beneficial, nutritional and therapeutic properties of these organisms.

By mid-1980, numerous other acidophilus products and multimicrobial supplements were developed.

Today, science and medicine understand the important health benefits of controlling the critical balance in the human digestive system through the introduction of probiotics. Doctors who prescribe medications for acid reflux disease often suggest probiotics as a companion to prevent digestive system imbalance, but there are many other benefits.

Those benefits include improved digestion of lactose, decreased incidence and duration of diarrheal illness, and improved immune system function. Probiotics' ability to decrease the risk of colon tumors has been documented in animal studies and is currently the subject of a large clinical trial in the European Union.

Controlled clinical studies have defined a role for probiotics in the prevention of allergy development in infants at risk for atopic dermatitis and for extending periods of remission of patients with inflammatory bowel disease.

Probiotic products may provide special benefits to aging consumers and to people faced with challenging life situations such as stress, antibiotic treatment or travel. People dealing with recurring gastrointestinal symptoms or vaginal infections could discuss with their doctors if probiotics may be useful to try.