Probiotic products have risen in popularity over the past few years, but surprisingly, most people still don't understand what probiotics are or how they contribute to health.

Probiotics are live "friendly" bacteria similar to those inhabiting your digestive tract. The gastrointestinal tract contains trillions of bacteria and viruses-especially in the small and large intestines. While most of these microorganisms are "friendly," and actually contribute to normal functioning of the body's systems, others can be harmful. Maintaining a balance of beneficial versus harmful microorganisms is essential to good health.

A number of factors, including antibiotic use, excessive sugar consumption, alcohol, stress and oral contraceptive or hormone use, can upset the balance of organisms in the gastrointestinal tract, resulting in bloating and abdominal discomfort. Immune function may also be affected, as the gastrointestinal tract is a major part of the body's immune system.

Consuming probiotics may help restore the typical balance of "friendly" and "unfriendly" bacteria in the gut, supporting healthy, efficient digestion. Some studies suggest other areas of health may also benefit from probiotic use, such as immune response and urogenital health.

Probiotics can be found in yogurt, milk, miso, tempeh and other fortified foods and beverages, as well as in supplement form. If you're considering using probiotics to support your health, keep the following misconceptions in mind:

Myth 1: Eating a container of yogurt every day will transform your digestive system.
Yogurt is a good source of probiotics, and some manufacturers have even conducted clinical trials demonstrating positive results from the use of their products. But just because a label states that a product contains probiotics doesn't mean that consuming it will prompt drastic changes in digestive function.

Yogurt labels generally do not disclose the amount of probiotics included- these products usually contain only small amounts, which may not be enough to provide substantial health benefits. I recommend taking from 4 billion up to 40 billion colony-forming units (CFUs) of probiotics daily, which is most easily obtained from supplements.

Myth 2: All probiotics are the same.
There are thousands of different probiotics, but they commonly come from two groups: Lactobacillus orBifidobacterium. Within these groups are different species, and within these species there are different strains. Each different strain offers unique health benefits, with actions as specific as increasing transit time of waste through the intestines to affecting frequency of bowel movements.

Because clinical research is limited, it can be difficult to recommend particular probiotic strains to target specific health concerns. However, it's generally believed that the more strains a product contains, the more benefits you're likely to experience. A wide variety of strains of "friendly" bacteria may yield the best results.

Myth 3: Digestive health is the only benefit of consuming probiotics.
While a good deal of research on probiotics surrounds digestive health, studies continue to demonstrate benefits for other areas. For example, a recent study published in the European Journal of Clinical Nutrition showed that consumption of a product containing a Lactobacillus strain for 12 weeks was associated with a 4.6 percent reduction in abdominal fat and a 3.3 percent reduction in subcutaneous fat¹. Researchers noted that the results suggest probiotics may have benefits for metabolic health.

Another study in the British Journal of Dermatology showed that breastfeeding mothers who drank probiotic-fortified milk from week 36 in pregnancy until the third month after childbirth reduced the incidence of eczema in their children, from birth to age two².

Research continues to demonstrate the importance of probiotics in maintaining good health, with scientists only beginning to discover the full potential of these beneficial bacteria. If you have gastrointestinal problems such as occasional stool irregularity, gas or bloating, or are interested in protecting your general health, I recommend consuming probiotics. Look for a product that provides a large number of colony-forming units (4 billion to 40 billion daily) from a wide variety of strains.

As always, to your health,
David N. Ilfeld, M.D.


1. Kadooka Y, Sato M, Imaizumi K, Ogawa A, Ikuyama K, et al.Regulation of abdominal adiposity by probiotics (Lactobacillus gasseri SBT2055) in adults with obese tendencies in a randomized controlled trial.Eur J Clin Nutr. 2010 Jun;64(6):636-43. Epub 2010 Mar 10.

2. Dotterud CK, Storrø O, Johnsen R, Oien T.Probiotics in pregnant women to prevent allergic disease: a randomized, double-blind trial.Br J Dermatol. 2010 Jun 9. [Epub ahead of print].