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Sunday, January 27, 2013

Probiotics: The "Good Bacteria"

Probiotics are live microorganisms (e.g., bacteria) that are either the same as or similar to microorganisms found naturally in the human body and may be beneficial to health. Also referred to as the “good bacteria” or “helpful bacteria,” probiotics are available to consumers in oral products such as dietary supplements and yogurts, as well as other products such as suppositories and creams. The U.S. Food and Drug Administration (FDA) has not approved any health claims for probiotics.

Probiotics, Prebiotics, and Synbiotics

Probiotics are not the same as prebiotics—nondigestible substances that stimulate the growth and/or activity of potentially beneficial microorganisms. The term “synbiotics” refers to products that combine probiotics and prebiotics.

About Probiotics

The concept behind probiotics was introduced in the early 20th century, when Nobel laureate Elie Metchnikoff, known as the “Father of natural immunity," proposed in The Prolongation of Life: Optimistic Studies that ingesting microorganisms could have substantial health benefits for humans. Microorganisms are invisible to the naked eye and exist virtually everywhere. Scientists continued to investigate the concept, and the term “probiotics”—meaning “for life”—eventually came into use.

Picturing the human body as a “host” for bacteria and other microorganisms is helpful in understanding probiotics. The body, especially the lower gastrointestinal tract (the gut), contains a complex and diverse community of bacteria. (in the body of a healthy adult, cells of microorganisms are estimated to outnumber human cells by a factor of ten to one.) Although we tend to think of bacteria as harmful “germs,” many bacteria actually help the body function properly. Most probiotics are bacteria similar to the beneficial bacteria found naturally in the human gut.

Various mechanisms may account for the effects of probiotics on human health. Possible mechanisms include altering the intestinal “microecology” (e.g., reducing harmful organisms in the intestine), producing antimicrobial compounds (substances that destroy or suppress the growth of microorganisms), and stimulating the body’s immune response.

Probiotics commonly used in the United States include Acidophilus (Lactobacillus acidophilus) and Bifidobacterium. There are many specific types of bacteria within each of these two broad groups, and health benefits associated with one type may not hold true for others.


Government Regulation of Probiotics

Government regulation of probiotics is complex. Depending on a probiotic product’s intended use, the FDA might regulate it as a dietary supplement, a food ingredient, or a drug. Many probiotic products are sold as dietary supplements, which do not require FDA approval prior to marketing. Dietary supplement labels may make claims about how the product affects the structure or function of the body without prior FDA approval, but they cannot make health claims (e.g. claims that the product reduces the risk of a disease) without the FDA’s consent. (for more information about the labeling of dietary supplements, see the FDA's Dietary Supplement Labeling Guide) A product that is marketed as a drug must meet more stringent requirements. It must be proven safe and effective for its intended use through clinical studies (tests in people) and be approved by the FDA before it can be marketed.

Use of Probiotics in the United States

In the United States, probiotics are available as dietary supplements (including capsules, tablets, and powders) and in dairy foods (such as yogurts with live active cultures). According to the 2007 National Health Interview Survey, which included a comprehensive survey on the use of complementary health approaches by Americans, “prebiotics/probiotics” ranked fifth among natural products used for children, but were not among the top-ranking products for adults. Although probiotic products are more popular in Europe and Japan than in the United States, the U.S. consumer market for probiotics is growing rapidly.

To help you identify yogurt that contains live and active cultures, the National Yogurt Association (NYA) developed the Live & Active Cultures seal. Look for it on the yogurt products you buy to make sure you’re getting the most from your yogurt.

Although the FDA has not approved any health claims for probiotics, they are used for a variety of gastrointestinal conditions such as infectious diarrhea, diarrhea associated with using antibiotics, irritable bowel syndrome, and inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease). Probiotics are also being used for preventing tooth decay and for preventing or treating other oral health problems such as gingivitis and periodontitis. Some—but not all—probiotic formulations have been widely studied and show considerable promise. However, the rapid growth in marketing and consumer interest and use has outpaced scientific research on the safety and efficacy of probiotics for specific health applications.

Research

The potential of probiotics to benefit human health in many different ways has stimulated great interest and activity among researchers. For example, the National Center for Complementary and Alternative Medicine (NCCAM) is part of the National Institutes of Health (NIH) Probiotic and Prebiotic Working Group, a trans-NIH effort to identify gaps and challenges in prebiotic/probiotic research.

Probiotic research is moving forward on two fronts: basic science (laboratory studies) and clinical trials to evaluate the safety and efficacy of probiotics for various medical conditions. Many early clinical trials of probiotics have had methodological limitations, and definitive clinical evidence to support using specific probiotic strains for specific health purposes is generally lacking. Nevertheless, there is preliminary evidence for several uses of probiotics, and more studies are under way. In particular, a recent review of the scientific evidence on the effectiveness of probiotics in acute infectious diarrhea concluded that there was evidence that probiotics may shorten the duration of diarrhea and reduce stool frequency but that more research was needed to establish exactly which probiotics should be used for which groups of people.

In 2008, the journal Clinical Infectious Diseases published a special issue on probiotics, which included "Clinical Indications for Probiotics: An Overview." Based on a review of selected studies, the authors classified several applications according to the strength of evidence supporting the efficacy of probiotics in prevention and/or treatment. For example, the authors concluded that strong evidence exists for acute diarrhea and antibiotic-associated diarrhea, and substantial evidence exists for eczema, particularly atopic eczema (a skin condition most commonly seen in infants). Promising applications include childhood respiratory infections, tooth decay, nasal pathogens (bacteria harbored in the nose), gastroenteritis relapses caused by Clostridium difficile bacteria after antibiotic therapy, and inflammatory bowel disease. The authors also discussed various potential future applications.

Studies also indicate that probiotics may reduce side effects associated with treatment for Helicobacter pylori infection, the cause of most stomach ulcers. A systematic review suggests that there is strong evidence that probiotics may reduce the risk of necrotizing enterocolitis, a severe intestinal condition of premature newborns. Other potential future applications include use in reducing cholesterol levels, weight management (overweight, obesity), and managing irritable bowel syndrome.

Safety and Side Effects

It appears that most people do not experience side effects from probiotics or have only mild gastrointestinal side effects such as gas. But there have been some case reports of serious adverse effects, and research on safety is ongoing. A 2008 review of probiotics safety noted that Lactobacillus rhamnosus strain GG (ATCC 53103) has been widely studied in clinical trials for a variety of conditions and generally found to be safe. Nevertheless, a recent review of Lactobacillus and Bifidobacterium noted that the long-term, cumulative effects of probiotics use, especially in children, are unknown, and also pointed to evidence that probiotics should not be used in critically ill patients.

Similarly, a 2011 Agency for Healthcare Research and Quality assessment of the "Safety of Probiotics used to Reduce Risk and Prevent or Treat Disease", partly funded by the National Center for Complementary and Alternative Medicine (NCCAM), concluded that the current evidence does not suggest a widespread risk of negative side effects associated with probiotics. However, the data on safety, particularly long-term safety, are limited, and the risk of serious side effects may be greater in people who have underlying health conditions.

Concerns have also been raised about the quality of probiotic products. Some products have been found to contain smaller numbers of live microorganisms than expected. In addition, some products have been found to contain bacterial strains other than those listed as ingredients.

If You Are Considering Probiotics:
  • The understanding of probiotics is a work in progress. Although probiotic products are marketed for many different uses, scientific evidence supporting specific uses is still limited, and the FDA has not approved any health claims for probiotics. Before using probiotics, learn as much as you can by talking to your health care provider and researching reliable sources of information.
  • Probiotic products may contain different types of probiotic bacteria and have different effects in the human body. The effects also may vary from person to person.
  • Do not replace scientifically proven treatments with unproven products and practices. Do not use a complementary health product, such as probiotics, as a reason to postpone seeing your health care provider about any health problem.
  • If you are pregnant or nursing a child, or if you considering giving a child a dietary supplement, such as probiotics, it is especially important to consult your (or your child’s) health care provider.
  • Anyone with a serious underlying health problem should be monitored closely for potential negative side effects while taking probiotics.
Recent research on probiotics has included clinical studies* focused on:
  • Diarrhea in infants
  • Irritable bowel syndrome and minimal hepatic encephalopathy (a complication of liver disease)
  • An antibiotic-resistant type of bacteria
  • Yogurt (in India, yogurt is called "dahi" or "curd") beverages as a way of giving high doses of probiotics to young children.

Laboratory studies that explore possible mechanisms of action for probiotics, providing a foundation for clinical research. Recent studies have found evidence that a strain of Lactobacillus reuteri might slow the growth of certain tumors, and that Lactobacillus acidophilus might enhance the effects of a vaccine against rotavirus infection—the most common cause of infectious diarrhea in infants and children worldwide.

Clinical research programs have designated probiotics as a high-priority topic for upcoming projects. These studies will focus on probiotics for addressing gastrointestinal disorders in infants and children, including necrotizing enterocolitis, colic, and irritable bowel syndrome; treating and preventing antibiotic-induced diarrhea; and enhancing the effects of flu vaccine.

*clinical research includes studies conducted under FDA-approved investigational new drug applications. Before these studies can proceed to medically vulnerable populations, researchers carry out rigorous trials to determine safety in healthy adults or people with mild medical conditions.

Selected References
AlFaleh KM, Bassler D. Probiotics for prevention of necrotizing enterocolitis in preterm infants. http://www.ncbi.nlm.nih.gov/pubmed/18254081. Cochrane Database of Systematic Reviews. 2008;(1):CD005496. www.thecochranelibrary.com.
Allen SJ, Martinez EG, Gregorio GV, et al. Probiotics for treating acute infectious diarrhoea. http://www.ncbi.nlm.nih.gov/pubmed/21069673. Cochrane Database of Systematic Reviews. 2010;(11):CD003048.
American Academy of Microbiology. Probiotic Microbes: The Scientific Basis. Report from a colloquium held in Baltimore, MD, November 5–7, 2005. Washington, DC: American Academy of Microbiology; 2006.
Bonifait L, Chandad F, Grenier D. Probiotics for oral health: myth or reality? http://www.ncbi.nlm.nih.gov/pubmed/19840501. Journal (Canadian Dental Association). 2009;75(8):585–590.
Drisko J, Bischoff B, Giles C, et al. Evaluation of five probiotic products for label claims by DNA extraction and polymerase chain reaction analysis. http://www.ncbi.nlm.nih.gov/pubmed/15986864. Digestive Diseases and Sciences. 2005;50(6):1113–1117.
Duffy LC, Sporn S, Hibberd P, et al. Lactobacilli and Bifidobacteria. In: Coates PM, Betz JM, Blackman MR, et al., eds. Encyclopedia of Dietary Supplements. 2nd ed. New York, NY: Informa Healthcare; 2010:469–478.
Food and Agriculture Organization (FAO) of the United Nations and World Health Organization (WHO). Guidelines for the Evaluation of Probiotics in Food. Report of a Joint FAO/WHO Working Group on Drafting Guidelines for the Evaluation of Probiotics in Food, London, Ontario, Canada, April 30-May 1, 2002. ftp://ftp.fao.org/es/esn/food/wgreport2.pdf.
Goldin BR, Gorbach SL. Clinical indications for probiotics: an overview. http://www.ncbi.nlm.nih.gov/pubmed/18181732. Clinical Infectious Diseases. 2008;46(suppl 2):S96–S100.
Hempel S, Newberry S, Ruelaz A, et al. Safety of Probiotics to Reduce Risk and Prevent or Treat Disease. Evidence Report/Technology Assessment no. 200. Agency for Healthcare Research and Quality. www.ahrq.gov/clinic/tp/probiotictp.htm.
Hibberd PL, Hoffman FA, Heimbach JT, eds. Developing probiotics as food and drugs: scientific and regulatory challenges. Clinical Infectious Diseases. 2008;46(suppl 2).
Hoffman FA, Heimbach JT, Sanders ME, et al. Executive summary: scientific and regulatory challenges of development of probiotics as foods and drugs. http://www.ncbi.nlm.nih.gov/pubmed/18181723. Clinical Infectious Diseases. 2008;46(suppl 2):S53–S57.
Iyer C, Kosters A, Sethi G, et al. Probiotic Lactobacillus reuteri promotes TNF-induced apoptosis in human myeloid leukemia-derived cells by modulation of NF-kB and MAPK signaling. http://www.ncbi.nlm.nih.gov/pubmed/18331465. Cellular Microbiology. 2008;10(7):1442–1452.
Kligler B, Cohrssen A. Probiotics. http://www.ncbi.nlm.nih.gov/pubmed/19007054. American Family Physician. 2008;78(9):1073–1078.
McDade-Ngutter C, Versalovic J, Alexander W, et al. National Institutes of Health Gastrointestinal Microbiota and Advances in Prebiotic and Probiotic Research conference summary. http://www.ncbi.nlm.nih.gov/pubmed/19328204. Gastroenterology. 2009;136(5):1473–1475.
Neish AS. Microbes in gastrointestinal health and disease. http://www.ncbi.nlm.nih.gov/pubmed/19026645. Gastroenterology. 2009;136(1):65–80.
Petrof EO. Probiotics and gastrointestinal disease: clinical evidence and basic science. http://www.ncbi.nlm.nih.gov/pubmed/20890386. Anti-Inflammatory and Anti-Allergy Agents in Medicinal Chemistry. 2009;8(3):260–269.
Preidis GA, Versalovic J. Targeting the human microbiome with antibiotics, probiotics, and prebiotics: gastroenterology enters the metagenomics era. http://www.ncbi.nlm.nih.gov/pubmed/19462507. Gastroenterology. 2009;136(6):2015–2031.
Sethi T. Probiotics in pediatric care. http://www.ncbi.nlm.nih.gov/pubmed/19608114. Explore. 2009;5(4):245–249).
Sharp RR, Achkar JP, Brinich MA, et al. Helping patients make informed choices about probiotics: a need for research. http://www.ncbi.nlm.nih.gov/pubmed/19343022. American Journal of Gastroenterology. 2009;104(4):809–813.
Snydman DR. The safety of probiotics. http://www.ncbi.nlm.nih.gov/pubmed/18181712. Clinical Infectious Diseases. 2008;46(suppl 2):S104–S111).
Tong JL, Ran ZH, Shen J, et al. Meta-analysis: the effect of supplementation with probiotics on eradication rates and adverse events during Helicobacter pylori eradication therapy. http://www.ncbi.nlm.nih.gov/pubmed/17229240. Alimentary Pharmacology and Therapeutics. 2007;25(2):155–168.
Vanderhoof JA, Young R. Probiotics in the United States. http://www.ncbi.nlm.nih.gov/pubmed/18181726. Clinical Infectious Diseases. 2008;46(suppl 2):S67–S72.
Zhang W, Azevedo MSP, Wen K, et al. Probiotic Lactobacillus acidophilus enhances the immunogenicity of an oral rotavirus vaccine in gnotobiotic pigs. http://www.ncbi.nlm.nih.gov/pubmed/18524434. Vaccine. 2008;26(29–30):3655–3661.

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These statements have not been approved by the U.S. Food and Drug Administration (FDA). This information is not intended to diagnose, treat, cure or prevent any disease.

Information conveyed herein is based on pharmacological and other records - both ancient and modern. No claims whatsoever can be made as to the specific benefits accruing from the use of any herb, essential oil, dietary and/or nutritional supplement, home remedy, or therapeutic regimen. Holistic Lifestyle Community Blog has provided this material for general information and education purposes only. It is not intended as a substitute for or to take the place of professional medical advice. If you have a medical emergency call 9-1-1. Before beginning any type of alternative, integrative, or conventional treatment regimen, it is advisable to seek the advice of a licensed physician or qualified health care professional. The mention of any product, service, or therapy is not an endorsement by Holistic Lifestyle Community Blog. Any mention in the Holistic Lifestyle Community Blog of a specific brand name is not an endorsement of the product.

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