You see them advertised on TV, find them in supplements and even in foods like yogurt. What are probiotics? Probiotics are live microorganisms often referred to as the “good bacteria”.  The digestive tract contains more than 400 different probiotic bacteria. It is felt that taking probiotics can help the “good bacteria” keep the natural balance of your digestive flora and promote healthy digestion and immunity.

Do they work? That is a hard question to answer. Probiotics do not undergo the same testing that is required for prescription medications and they do not have the same rigorous studies to support their use. There is a definite need for more studies to fill the gap between health claims and what research and studies support. The good news is that most probiotics do not have significant side effects if you are healthy. This allows you to try the product to see if it works for you. If one product does not work then try another. The following are the probiotics that have shown some evidence of benefit:

  • For the prevention of antibiotic caused diarrhea:Lactobacillus GG (CulturelleTM supplement), Saccharomyces boulardii (FlorastorTM supplement), and other probiotic mixtures appear to be effective. The antibiotic and probiotic dosing should be separated by at least 2 hours to avoid a possible drug interaction.
  • For the prevention of traveler’s diarrhea the studies have had mixed results. The combination of L acidophilus, L bulgaricus, B bifidum and S thermophilus has been used. S boulardii may also be useful.
  • For symptoms of irritable bowel such as abdominal discomfort, bloating, and difficult bowel movements Bifidobacterium infantis (AlignTM) and some species/strains of Lactobacillus have shown some benefit.
  • For maintenance of regularityBifidobacterium animalis DN 173 010 aka Bifidus RegularisTM (ActiviaTM) needs more human studies but a trial of 1-2 servings a day for 10-14 days can be conducted to see if it works.
  • For chronic constipationLactobacillus casei Hirota (YakultTM) showed improved symptoms seen after 2 weeks in one study.
  • For additional studies of other conditions and the use of probiotics see the US Probiotic website sponsored by the California Dairy Research Foundation and the Diary & Food Culture Technology:
  • For additional information about various microorganisms found in probiotic products see the US National Library of Medicine and National Institutes of Health website:

Discuss the use of Probiotics with your physician before you begin taking them. The use of probiotics should not replace medical care by a physician and should not delay seeking care for symptoms that are of concern. This is especially important for newborn babies, pregnant women, women who are breast feeding, patients with weak immune systems and others with major illnesses. Ask your physician for recommendations on the appropriate probiotic strains for your specific health condition as well a reputable supplier.

Useful information:
Which microorganism is best? There are a number of different microorganisms that are included in commercial probiotic products. The benefits of the product are strain-specific and not all strains or organisms are useful.
What does CFU mean and is a bigger number better? The term CFU stands for the Colony Forming Unit. It is the amount of “live” microorganisms per dose. A large number of CFUs in a product does not necessarily mean that it is better.
Why do some products require refrigeration and others do not? Probiotics are composed of “live” microorganisms. They are very sensitive to extreme temperatures and many products require refrigeration. Some manufacturers use specialized processes to protect the microorganisms and this allows them to be stored at room temperature.  Freeze-drying (also known as lyophilization) or the use of a specialized enteric coated capsule are processes that protects the live microorganisms against heat, moisture and acid. The challenge that probiotics have to overcome is getting the microorganisms into the intestine alive. Therefore it is important to follow the storage directions and expiration dates to ensure that the bacteria remain alive and active.
What manufacturer should I use? Even though a product has the same microorganism in the same amount, two products made by different manufacturers may not produce the same results. Unlike prescription medications, Probiotics sold as dietary supplements do not undergo the same testing and quality assurance processes. The supplement market is filled with many manufacturers and there are no studies that compare the different brand name products head-to-head for efficacy. It is important to buy supplements from a good source. Look at product information and also their website. Their goal should be to educate and not just to promote and sell. What information should you look for?

  • Product Information: directions for use, side effects, precautions, ingredients, probiotic strains used, CFUs for the individual strains, storage instructions, drug interactions, etc
  • Resources: Additional resources should be available to help you find more information
  • Studies: References to studies that support their information
  • Consumer Hotline: This will allow you to ask specific questions about their products.

1.  Probiotics: An Update. Pharmacist’s Letter/Prescriber’s Letter 2009;25(9):250908.
2. Health Benefits of Taking Probiotics, The Harvard Medical School Family Health Guide. accessed April 20, 2012.
3. Oral probiotics: An Introduction, National Center for Complimentary and Alternative Medicine’ accessed April 20, 2012

By Alicia Sakai, PharmD