Below you'll find background information on probiotics. These "friendly" microbes are changing the way we look at and think about bacteria.

The word probiotic literally means "for life" and it is used to describe conventional foods or dietary supplements that contain these "friendly", "beneficial" or "good" bacteria. Probiotics are defined by the WHO (World Health Organization) as "Live microorganisms which when administered in adequate amounts confer a health benefit on the host." (ftp://ftp.fao.org/es/esn/food/wgreport2.pdf, 2002)". In order to be called probiotics, these microorganisms need to be tested and shown to provide a benefit to the human body.

Probiotic foods are foods that deliver a significant amount of active probiotic cultures when consumed. Certain yogurts and fermented dairy drinks are the most common probiotic foods. Several different types of probiotic cultures (some strains of Lactobacillus casei, Bifidobacterium lactis) are being introduced in an expanding variety of dairy products around the world.

No. There are many strains of beneficial cultures that have probiotic potential. The benefits associated with probiotics are strain-specific and must be established through adequate studies. In addition, the range of benefits can vary according to the amount consumed.

Live cultures are microbes used to ferment foods. Not all live and active cultures are probiotics therefore a product that contains live and active cultures does not necessarily qualify as a probiotic.

Probiotics from either foods or supplements can be effective. What's important is a strain or combination of strains that have been tested for efficacy. Food sources of probiotics may have an advantage in that they most often offer good nutrition along with the probiotic bacteria. For example, probiotic dairy foods can provide a much needed source of calcium for most of those individuals who are unable to enjoy most dairy foods because of lactose-intolerance.

In addition, dairy products can buffer stomach acids and may increase the chance that probiotics will survive and make it to the intestine.

Probiotics provide a beneficial action on different body functions. If probiotic cultures are regularly consumed and while they're still alive and active, they are able to establish themselves in the digestive system for short periods of time and once there, they can offer beneficial effects.

However, in order to do so, they should be capable of surviving passage through the digestive system. Only certain strains of probiotic bacteria are able to do so; others are quickly destroyed by the digestive enzymes in the stomach. Certain beneficial cultures are able to survive and pass through into the colon in sufficient numbers. Therefore, the survival rate of the specific strain of bacteria contained in a probiotic product is an important factor when determining its potential benefits (Oozeer R et al., 2003). To date, several probiotic strains have demonstrated the ability to survive, such as certain Bifidobacterium and Lactobacillus strains (Berrada et al., 1991; Pochart et al., 1992).

The complex ecosystem of bacterial microorganisms that lives in the intestinal tract is commonly referred to "intestinal microflora" or "gut flora", essential to our well-being. Over 1000 species of bacteria reside in the gastrointestinal tract. There are actually about 10 times as many bacteria in an adult's intestinal tract as there are cells in the entire body. A person is born without this intestinal bacterial ecosystem; it starts to develop while we're still infants and becomes more sophisticated once food is introduced in the diet.

While most of these bacteria are not harmful, some are actually beneficial and important for normal growth and development. Under normal circumstances, the "friendly" bacteria far outnumber the "bad," and the pH of our intestinal tract tends to swing downward, making it a less hospitable environment for harmful bacteria. Factors such as stress, lack of sleep, antibiotics, illness, aging, and eating habits can alter the types and number of bacteria.

The Intestinal microflora also plays an important role in the maturation of the immune system and in the development of normal gastrointestinal function. The microflora that occupies the lining of the intestinal tract acts as a physical barrier. It reinforces the barrier function of the intestinal mucosa by partially blocking the passage of certain bacteria. Conversely, an unbalanced microflora system will also adversely affect these intestinal functions.

• Probiotics and the Immune system
• About 70 percent of the body's immune system is located in the digestive tract. Consuming certain specific probiotics can help, in combination with a balanced diet and healthy lifestyle, support the immune system by providing a regular source of "friendly" bacteria to the intestinal tract, and supporting the functioning of the immune system.
•  
• An essential part of the immune system, called the Gut-Associated Lymphoid Tissue or GALT, consists of several types of lymphoid tissue that produce and store immune cells. Some research suggests that probiotics have a beneficial action on the intestinal microflora, helping support the functioning of the intestinal lining while helping to regulate critical components of the immune system such as lymphocytes, antibodies and natural killer cells (Woodcock et al., 2003; Parra et al., 2004; Marcos et al., 2004; Yasui et al., 2003; Cross, 2004).
• 
  
• Probiotics and the Digestive System
• The digestive system is an extremely complex environment that performs many vital functions. Digestive comfort and well-being is a multidimensional concept that includes physical and psychological components. It refers to the ability of the digestive system to function properly and to help support quality of life. A well-functioning digestive system also means we are less likely to experience digestive complaints, such as discomfort, flatulence and bloated feeling.
•  
• Intestinal transit is the process by which gut intestinal contents pass through the digestive system. Slow intestinal transit or occasional irregularity may be a source of daily discomfort and the physical and psychological consequences on the quality of life should not be underestimated.
•  
• Some research suggests that certain probiotics can help optimize the function of the gastrointestinal tract, leading in turn to better daily well-being.

Probiotics have received a lot of attention over the last few years, but they are a far from recent discovery. The benefits of certain foods known to contain probiotic microbes have been recognized for centuries. There's even a Persian tradition that asserts that the biblical patriarch Abraham owed his longevity to a diet of fermented milk. Louis Pasteur first identified lactic acid bacteria in 1857. But it was the father of modern immunology, Russian physiologist and Nobel-prize winner Elie Metchnikoff (1845-1916) who was recognized as the discoverer of probiotics. He was the first to suggest that consuming bacteria could have a beneficial effect on health. In 1907, he proposed that the acid-producing organisms in fermented dairy products could prevent what he called "fouling" in the large intestine and, if consumed regularly, lead to a longer, healthier life.

He based his theory, in part, on the observation that Bulgarians from the Balkan region of Eastern Europe, who regularly consumed fermented dairy products, especially yogurt, were known for their longevity and superior health. Since then, decades of microbiological and clinical research have supported the proposition that ingesting certain probiotics can help improve different body functions.