Articles

Probiotics: Should You Be Taking Them?

By Tiffany Spudich, R.Ph., Pharm. D.

It has been estimated that more than 1000 different types of bacteria make their homes on humans. Human beings, like all animals, play host to many types and high numbers of microbes in our mouths, intestines, respiratory system, on our skin, and in women's vaginal tracts. One estimation is that there are more microbes associated with the human body (about 1014, or 100,000,000,000,000 bacterial cells) than there are human cells in it (about 1013).

Probiotic literally means "for life." Basically probiotics are live, microbial cultures used for a health benefit. The primary requirements for a microbe to be considered a probiotic are that the microbe must be alive when administered, must be documented to have a health benefit, and must be administered at levels shown to achieve the benefit.
For centuries, folklore suggested that fermented dairy products containing live active cultures are healthful. Recent controlled scientific investigation supports these traditional views, suggesting that probiotics are a valuable part of a healthy diet. Data suggests probiotic therapy can be beneficial for a multitude of conditions including diarrhea, high blood pressure, elevated blood cholesterol,allergies/sensitivities, the immune system, oral health, lactose intolerance, irritable bowel syndrome, inflammatory bowel disease (including Crohn's disease and ulcerative colitis), vaginal infections such as yeast infections, kidney stones, and overall general health. However, the specifics of their role in various health conditions are very complicated, and research is still actively being conducted to clarify the role of probiotics in human health. Positive clinical studies have been designed using a variety of strains, subjects, clinical endpoints and doses. Efficacious levels vary in these individual studies, and range from 108-11 viable cells per day. Currently it is not possible to give a specific recommendations on levels needed. It depends on the product, the consumer, and the anticipated health benefit. Most studies administer the probiotic daily, sometime multiple times each day. Dose effects are often not included in human studies.

Most probiotic products contain the bacteria from the genera Lactobacillus or Bifidobacterium, although other genera, including Escherichia, Enterococcus, and Saccharomyces (a yeast) have been marketed as probiotics. However, not all probiotic strains are the same. Different strains of even the same genus or species are not necessarily the same. For example, two different strains of Lactobacillus acidophilus might not have the same probiotic activity. One analogy is to make a comparison to dogs, which are all the same species, but different breeds of dogs can be very different. A beagle may be good for hunting while a German shepherd is a good watchdog. One breed of dog should not be expected to be right for all purposes. Although strains of bacteria are very similar, some strains of probiotics, even of the same species, can have very different characteristics. That is why it is important to know what exact strain is being used and what evidence is available for the specific strain being used. By stating a specific strain on the label, the manufacturer is showing some commitment to making a standardized and effective product.
However, looking for strain identification on the label can be challenging because the company may use numbers, letters or another name to indicate the strain. But as a general rule, the bacteria name is in italics and the strain is printed in regular type.

At a minimum, probiotic products should be safe, effective, and should maintain their effectiveness and potency through the end of product shelf life. Many probiotic bacteria are stable and remain alive as dried bacteria such as in capsule formulations, especially if kept refrigerated, and in dairy products. If bacteria are dried and stabilized properly, they remain alive and start to grow again after they reach the moist environment inside one's body. However, stability differs for different strains, different storage conditions, and different product formats. Some research studies have shown that probiotic products do not always contain the levels of bacteria they claim or that would be expected in the product. The producer must identify strains and conditions of storage that will assure consumers that the probiotic will stay alive at efficacious levels through the end of shelf life. It is important to purchase your product from a responsible company and be sure to follow manufacturers' recommendations on how to store the product once purchased.

Sometimes it is claimed that probiotics must survive intestinal transit to be effective. Although there is little doubt that the ability of probiotics to grow and metabolize as they transit the intestinal tract can contribute to health benefits, there are also cases where this may not be necessary. For example, preliminary research suggests that some probiotics may reduce the levels of Streptococcus mutans, the cause of dental caries, in the oral microbial community. A health benefit of this type would not require survival through the intestine. However, traveling through the human digestive tract can be a challenge for bacteria. High acid levels in the stomach and exposure to pancreatic secretions such as digestive enzymes and bile in the small intestine can lead to the injury and death of a percentage of orally administered probiotics. Although some bacteria are more resistant than others to this stress, consumption of probiotics with food, including milk, yogurt and other dairy products, buffers stomach acid and can increase the chance that the bacteria will survive into the intestine. Also, some formulations include a special encapsulation that is thought to aid in transit to the lower gastrointestinal tract.

Dairy foods can protect the probiotic bacteria, and refrigerated storage of dairy products can help to promote probiotic stability. Although the lactic acid content of yogurt can be a barrier to culture stability, short-term refrigeration generally promotes stability. Yogurts sold in the United States are primarily made with the yogurt starter bacteria Streptococcus thermophilus and Lactobacillus bulgaricus. As long as a yogurt is not heat treated after fermentation, the yogurt should contain high numbers of both of these bacteria. This is the situation with all yogurts that display the Live Active Culture Seal, a program administered by the National Yogurt Association. For more information about this program one can visit www.aboutyogurt.com.
Most of these yogurts also carry additional bacteria added for their health effects. One type of yogurt by Dannon®, called ACTIVIA®, contains Bifidobacterium animalis DN-173 010 which has been studied in patients with irritable bowel syndrome. This particular strain has been shown to help with slow intestinal transit and has been proven to survive passage through the digestive system, arriving into the large intestine as a live culture.

Although data has suggested a beneficial effect of probiotic therapy in certain patient populations, further studies are required to confirm these results. It is always recommended to include your health care professional in any decision about your health. People who are immunocompromised, have recent or upcoming surgery, or have an underlying disease or gut condition should take probiotics only under the care of a doctor, and even then, should only take well defined and characterized products produced by reputable companies.
The following table outlines specific probiotics which have been researched in association with these conditions:

1. www.usprobiotics.org
   
2. Egert M, de Graaf AA, Smidt H, de Vos WM, Venema K. Trends Microbiol. Beyond diversity: functional microbiomics of the human colon. 2006 Feb;14(2):86-91. Epub 2006 Jan 10.
3. Resemary R. Berardi, PharmD, FCCP, FASHP, FAPhA. Irritable Bowel Syndrome: Update on Medical Management and the Use of Probiotics. www.uspharmacist.com
4. www.peacehealth.org
   
5. www.aboutyogurt.com
   
6. www.activia.us.com