In 2001, “probiotics” was defined by a group of scientists convened by the Food and Agriculture Organization of the United Nations (New York) as “live microbes which when administered in adequate amounts confer a health benefit on the host.” (See _en.stm.) What is implied in this definition is that probiotics are safe and well-defined, that is, purified with known genus, species and strain. (See

As probiotics become more visible and accepted in the U.S., there is a need to adhere to this definition. Often, the term is used without meeting the minimum criteria of being alive when administered, having been documented to have a beneficial physiological effect on humans, and, when used, posting truthful claims about content or performance in a product.

No worldwide legislative body currently regulates the use of the term “probiotic.” As a result, much abuse exists and many misconceptions are promoted through the Internet, consumers, manufacturers and even some scientists. The following offers a perspective on 10 common myths about probiotics.

Myth 1. Microbes should be avoided.
Microbes are on, in and around us, but rarely do people think of them as anything but negative. One need look no further than retail shelves--with their host of antibacterial products initially designed for hospital use but increasingly marketed to the general, healthy population--to see how we are obsessed with eliminating bacteria.

While there is no denying the potential some microbes have for causing harm to people and animals, most people do not realize that microbes have the potential for good as well. Without the abundance and diversity of common microbes that inhabit our bodies, our immune systems would be woefully under active and the few microbes we encounter that cause disease would be ever more successful.

The idea that there is value to intentionally supplementing our bodies with additional beneficial microbes (probiotics) through fermented dairy foods was proposed about 100 years ago. In more recent years, modern scientific approaches have been applied to probiotics to improve human health including: reducing symptoms of lactose intolerance; reducing the incidence or duration of some diarrheal illnesses (especially in infants and young children); and improving immune system function, both to increase anti-pathogenic activity and decrease inflammatory or allergic responses. Research is emerging on other effects as well.

Myth 2. The most important attributes of probiotics are adherence, human origin and production of bacteriocins.
In the early years of scientific investigation of probiotics, before much was known about probiotic function, assumptions about needed probiotic characteristics included that they must: 1. Be of “human origin”; 2. Adhere to intestinal cells and colonize the gut; and 3. Produce antimicrobial compounds such as bacteriocins.

Over time, researchers found little evidence proving these characteristics play a role in probiotic function in the human. Three difficulties with these assertions include that, to be of use, these attributes must be able to be reliably measured in humans. This has not been done with any of these attributes. Second, these attributes have never been shown to be what is responsible for probiotic function. Third, in light of the lack of evidence documenting their involvement in probiotic functionality, undue emphasis is still placed on their importance, causing confusion for consumers, regulatory agencies and even scientists.

Based on the current state of knowledge, it is reasonable to say that the requirements for probiotics in general are: 1. They are safe under conditions of use; 2. They have been documented to improve human health; and 3. They can be delivered alive in the product.

Myth 3. Probiotics must survive transit through the intestinal tract to be effective.
The ability of a probiotic to survive intestinal transit after oral consumption does provide some useful information, especially as it relates to the probiotic's potential ability to function alive throughout the GI tract. It is important to recognize there are some probiotic functions that would not require survival at high numbers in feces. For example, fecal survival is likely not important for activities such as prevention of dental caries, inhibition of Helicobacter pylori in the stomach, and some forms of immune system modulation. Therefore, whether or not a probiotic survives transit through the intestinal tract should not be considered a requirement of probiotics, and may only be important for certain probiotic functions.

Myth 4. Prebiotics are better than probiotics and you do not need to worry about keeping prebiotics alive.
For some applications, prebiotics may be the better choice, for others it may be probiotics. Prebiotics are non-digestible substances that, when consumed, provide a beneficial physiological effect on the host by selectively stimulating the favorable growth or activity of a limited number of indigenous bacteria (1995, Gibson & Roberfroid). They commonly are associated with discussions on probiotics because both probiotics and prebiotics have a role in promoting gut health through action on gut flora. Unlike probiotics, prebiotics are not alive. So, why choose one over the other?

  • While probiotics and prebiotics have some overlapping functions, their roles can be quite different. They also have different technological properties in foods. Some of their differences include:

  • With probiotics you can select or design your strain to have the characteristics you want. With prebiotics you are stimulating native flora, which may or may not achieve the desired function.

  • A broader range of health benefits has been proposed for probiotics, impacting colonized regions of the body including the mouth, throat, stomach, small intestine, colon and vaginal canal. The impact of prebiotics is more focused on the colon.

  • Because there is no worry about keeping prebiotics alive, they can be used in a wider range of products.

    Myth 5. Product labels provide good information on probiotics.
    Products containing probiotics in the U.S. include both foods (mostly dairy products) and dietary supplements. Neither group is labeled optimally for communication of essential information to consumers.

    Food products provide little more than a small-print reference to containing certain bacteria, such as Lactobacillus acidophilus and/or Bifidobacterium, with no reference made to levels delivered (this is considered a “trade secret” by many manufacturers), strains used, or health effects documented for the level of prebiotics used in the product. This also applies to use of the “Live Active Culture” seal. The seal is a handy way to identify yogurts that have not been pasteurized after fermentation (all yogurts use pasteurized milk) and contain at least 107cfu/ml of the starter bacteria (S. thermophilus and L. bulgaricus) at the end of shelflife. However, if additional probiotic bacteria are listed on the label, the LAC seal gives no information on the level of these bacteria. Therefore, a yogurt carrying the LAC seal may not deliver an efficacious level of supplementary probiotic bacteria.

    Supplements generally list the different microbes contained in the product and the level of total microbes contained in a dose. What is often missing, however, is information identifying each strain used (different strains even of the same species may have quite a different function and documentation), the levels of each strain, and where the consumer can get information on substantiation of claims made for the specific product. Furthermore, studies have been published that question how reliably probiotic supplements meet the stated label claims with regard to numbers of bacteria delivered at the end of shelflife and proper identity of bacteria contained within.

    Myth 6. Dietary supplement probiotic products are unregulated.
    The FDA regulates dietary supplements. Regulations stipulate that products must be labeled in a truthful and not misleading fashion, and that the product does not present a significant or unreasonable risk of illness or injury under the recommended conditions of use. Manufacturers must disclose to the FDA in a letter any health benefit claims they intend to use, but this is not an approval process. The manufacturer is expected to have documentation that validates its assertion of safety and any health benefit claims and must present this documentation to the FDA if requested. In the case of “new” dietary supplements (those not marketed prior to October 15, 1994), notification of the FDA 75 days in advance of marketing providing a reasonable basis for asserting the product's safety is required. Labels for dietary supplements cannot carry any messages, either implied or overt, presenting the product as a drug, i.e., useful in the treatment, mitigation, diagnosis or cure of a disease.

    No approval requirement currently exists for marketing 'grandfathered' dietary supplements or making label claims and, therefore, it is up to the FDA to prove that these products are unsafe or mislabeled. Because of limited FDA resources, although probiotic dietary supplements labeled as drugs will incur a quick warning letter from the FDA, other aspects of label inaccuracies have not resulted in FDA action. In effect, there is no assurance that labels on probiotic dietary supplements are accurate with regard to the type of microbe contained within, the levels supplied, or the claimed benefits to human health.

    Myth 7. The FDA will not allow claims about probiotics on foods.
    Health claims, or statements that provide an association of a food or food ingredient and reduced incidence of a disease are allowed if approved by the FDA or by a recognized authoritative body stipulated by the FDA. Structure/function statements, which relate the food or ingredient to the normal function of the human body, are allowed on both foods and supplements. Statements such as “supports your body's natural defenses” are allowed, if they are truthful and not misleading.

    Myth 8. Probiotics are GRAS.
    For a substance to be considered GRAS (“generally recognized as safe”), it must be well defined. The term “probiotic” is very broad. Published studies on probiotics include a range of genera and species of bacteria and yeast. Lactobacillus species, Bifidobacterium species, Streptococcus thermophilus, Lactococcus lactis, Enterococcus species, Bacillus species, Escherichia coli and Saccharomyces boulardii are considered probiotic microbes. It is impossible to consider such an array of microbes together for GRAS determination.

    The term GRAS is used only under specified conditions. One cannot say, “Lactobacilli are GRAS” but may say say, “Lactobacilli are GRAS for use as fermentation agents in foods.” This becomes quite relevant when considering how probiotics are formulated and used. For example, a Lactobacillus bulgaricus that has been traditionally used to ferment foods and has been consumed in food at levels of 1010-1011 live microorganisms/day would likely qualify as a GRAS use. A Lactobacillus rhamnosus isolated from a human biopsy sample that has been purified, grown, concentrated, enteric-coated and fed as a capsule at 1012-13/day would need to be reviewed separately for GRAS consideration.

    Myth 9. One yogurt each day is enough to enjoy benefits of probiotics.
    Although consuming probiotics through fermented dairy products is a great way to get the nutrition of milk along with live bacteria, in the U.S. market, it is hard to tell what type of probiotic content yogurt has. Yogurts that carry the Live Active Culture seal deliver an adequate quantity of yogurt starter bacteria, but the level of any additional bacteria cannot be presumed. One exception is DanActive, a fermented milk product by Dannon (The Groupe Danone, Tarrytown, N.Y.) that discloses it contains 1010 Lactobacillus casei per serving. Without knowing that yogurts carry high enough levels of documented probiotic strains, we cannot assert that yogurt is the best way to get probiotics. Some studies have linked yogurt consumption with benefits including improved digestion of lactose, reduced incidence of urinary tract infections, reduced allergy symptoms, improved resistance to some intestinal infections and a decreased risk of vaginal infections. However, the role of the microbes in these effects is not always clear from the studies.

    Myth 10. In the U.S., people are really excited about probiotics and all the new products containing them on the market.
    While there seems to be a growing awareness about probiotics in the U.S. today and companies like Dannon are making strides in introducing new products with probiotics, it remains that few Americans know the word “probiotic” or realize that microbes can be good for you. In Europe and Japan, probiotic-containing food products abound, and the general culture is better aware of the concept. In the U.S., there is still a great void in awareness of probiotics.

    Mary Ellen Sanders, Ph.D., through her business Dairy & Food Culture Technologies (Centennial, Colo.), consults on all aspects of probiotic applications in foods and supplements. She believes probiotics will flourish if products are scientifically validated, responsibly produced and accurately labeled. She strives to balance the potential consumer benefits of probiotics with an understanding of the emerging science. She can be reached at:, 303-793-9974 or