The idea of friendly bacteria might take a little getting used to, but these microorganisms have been around for a quite a while. Now probiotics are being researched for their potential benefits, as well as side effects.
Here is some information about probiotics from The National Center for Complementary and Alternative Medicine:
An Introduction to Probiotics
Probiotics are live microorganisms (in most cases, bacteria) that are similar to beneficial microorganisms found in the human gut. They are sometimes also called "friendly bacteria" or "good bacteria." Probiotics come mainly in the form of dietary supplements and foods.
There is limited evidence supporting some uses of probiotics. Much more scientific knowledge is needed about probiotics, including information regarding their safety and appropriate use. Effects found from one species or strain of probiotics do not necessarily hold true for others, or even for different preparations of the same species or strain.
What are Probiotics?
Experts have debated how to define probiotics. One widely used definition, developed by the World Health Organization and the Food and Agriculture Organization of the United Nations, is that probiotics are "live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host." Microorganisms are tiny living organisms—such as bacteria, viruses, and yeasts—that can be seen only under a microscope.
Probiotics are available in foods and dietary supplements (for example, capsules, tablets, and powders) and in some other forms as well. Examples of foods containing probiotics are yogurt, fermented and unfermented milk, miso, tempeh, and some juices and soy beverages. In probiotic foods and supplements, the bacteria may have been present originally or added during preparation.
Many probiotics are bacteria similar to those naturally found in people’s guts. Most often, the bacteria come from two groups, Lactobacillus or Bifidobacterium. Within each group, there are different species (for example, Lactobacillus acidophilus and Bifidobacterium bifidus), and within each species, different strains (or varieties). A few common probiotics, such as Saccharomyces boulardii, are yeasts, which are different from bacteria.
Some probiotic foods date back to ancient times, such as fermented foods and cultured milk products.
Each person’s mix of bacteria varies
First, the world is full of microorganisms (including bacteria), and so are people’s bodies—in and on the skin, in the gut, and in other orifices. Friendly bacteria are vital to proper development of the immune system, to protection against microorganisms that could cause disease, and to the digestion and absorption of food and nutrients. Each person’s mix of bacteria varies. Interactions between a person and the microorganisms in his body, and among the microorganisms themselves, can be crucial to the person’s health and well-being.
This bacterial "balancing act" can be thrown off in two major ways:
- By antibiotics, when they kill friendly bacteria in the gut along with unfriendly bacteria. Some people use probiotics to try to offset side effects from antibiotics like gas, cramping, or diarrhea. Similarly, some use them to ease symptoms of lactose intolerance—a condition in which the gut lacks the enzyme needed to digest significant amounts of the major sugar in milk, and which also causes gastrointestinal symptoms.
- "Unfriendly" microorganisms such as disease-causing bacteria, yeasts, fungi, and parasites can also upset the balance. Researchers are exploring whether probiotics could halt these unfriendly agents in the first place and/or suppress their growth and activity in conditions like:
- Irritable bowel syndrome
- Inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease)
- Infection with Helicobacter pylori (H. pylori), a bacterium that causes most ulcers and many types of chronic stomach inflammation
- Tooth decay and periodontal disease
- Vaginal infections
- Skin infections
Another part of the interest in probiotics stems from the fact there are cells in the digestive tract connected with the immune system. One theory is that if you alter the microorganisms in a person’s intestinal tract (as by introducing probiotic bacteria), you can affect the immune system’s defenses.
Areas of Research
Scientific understanding of probiotics and their potential for preventing and treating health conditions is at an early stage.
Areas of interest to researchers on probiotics include:
- What is going on at the molecular level with the bacteria themselves and how they may interact with the body (such as the gut and its bacteria) to help prevent and treat diseases. Advances in technology and medicine are making it possible to study these areas much better than in the past.
- What happens when probiotic bacteria are treated or are added to foods—is their ability to survive, grow, and have a therapeutic effect altered?
- The best ways to administer probiotics for therapeutic purposes, as well as the best doses and schedules.
- Probiotics’ potential to help with the problem of antibiotic-resistant bacteria in the gut.
- Whether they can prevent unfriendly bacteria from getting through the skin or mucous membranes and traveling through the body (e.g., which can happen with burns, shock, trauma, or suppressed immunity).
Side Effects and Risks
Probiotics’ safety has not been thoroughly studied scientifically. More information is especially needed on how safe they are for young children, elderly people, and people with compromised immune systems.
Probiotics’ side effects can include digestive problems (such as gas or bloating). More serious effects of probiotics have been seen in some people. Probiotics might theoretically cause infections that need to be treated with antibiotics, especially in people with underlying health conditions. They could also cause unhealthy metabolic activities, too much stimulation of the immune system, or gene transfer (insertion of genetic material into a cell).
Important Points To Consider
- If you are thinking about using a probiotic product as complementary or alternative therapy, consult your health care provider first. No complementary or alternative therapy should be used in place of conventional medical care or to delay seeking that care.
- Effects from one species or strain of probiotics do not necessarily hold true for others, or even for different preparations of the same species or strain.
- If you use a probiotic product and experience an effect that concerns you, contact your health care provider.
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Source: The National Center for Complementary and Alternative Medicine, An Introduction to Probiotics, Created January 2007, Updated August 2008