Thomas Peller, MD
Gastroenterology
Southside Medical Clinic
Eau Claire


The World Health Organization (WHO) has defined probiotics as “live organisms which, when administered in adequate amounts, confer a health benefit on the host”. A probiotic is not a drug, but a dietary supplement. Yogurt, which many consider a probiotic, is only a probiotic when it has been fortified with enough live active microorganisms to meet this definition. An example of a yogurt that is a probiotics is Activia made by Dannon. To understand how probiotics may benefit humans, a little background biology is in order.

The human gut is home to trillions of bacteria cells. Some estimate over 500 different bacteria make up over a 100 trillion bacteria that live in our human digestive system. This collection of organisms is called a microbiota (micro meaning small and biota meaning a particular region or habitat).

Our gut is in a mutual relationship with these organisms. The intestinal tract provides a place for the organisms to live and provides nutrients for the bacteria.

The bacteria helps us in at least three ways:

  • Prevent infection by pathogenic bacteria
  • Assist with nutritional needs, such as producing short chain fatty acids (an important energy source for the intestine) and some vitamins (Vitamin K, folate and some of the B vitamins)
  • Immune system development

The human gut microbiota has changed in modern times. Reasons are multiple and include improved sanitation and living conditions, refrigeration and use of antibiotics. When the gut microbiota is altered in diseases, it is called dysbiosis. In most diseases, researchers are not sure if the alteration in the bacteria is causing the disease or just an effect of the disease process.

So can probiotics help when there is an imbalance in our gut microbiota? The answer is yes, but it is more complicated than most people realize. Most probiotics in commercial use have only one strain of bacteria. Remember, there are over 500 different strains of bacteria in our intestinal system. Just like different antibiotics need to be used to treat different infections, research is showing that different probiotics seem to work in different disease states. Some of the diseases that have been evaluated to assess the effectiveness of probiotics include: antibiotic associated diarrhea, viral intestinal infections (gastritis); irritable bowel syndrome and inflammatory bowel disease (IBD) which includes ulcerative colitis (UC) and Crohn’s Disease. Lactobacillus acidophils, Lactobacillus casei, Lactobacillus rhamnosus or Saccharomyces boulardii have been shown in several studies to help prevent antibiotic associated diarrhea. These same probiotics have also been shown to reduce the length of time a patient suffers with symptoms from viral gastroenteritis. Other strains of bacteria have not shown the same effect.

Irritable bowel syndrome is a chronic disorder that is characterized by symptoms of abdominal pain with associated bowel habit changes. The cause of IBS is poorly understood. Some studies suggest that at least some of the symptoms of IBS could be related to a change in the microbiota. Studies in patients with IBS who have been given bifidobacteria species have shown an overall improvement in how they feel, but the studies did not show improvement in bowel symptoms. No improvement was noted when taking Lactobacillus type strains.

Inflammatory bowel disease includes ulcerative colitis (UC) and Crohn’s. There is evidence that points to the microbiota playing an important role in the inflammatory process that occurs in the intestine. Probiotics have been more beneficial in patients with UC compared to patients with Crohn’s. The bacteria species Escherichia coli Nissle 1917, and a combination probiotic called VSL#3 have shown some benefit in UC. Studies with Lactobacillus and “Bifodobacteriums” have not demonstrated improvements.

Side effects from probiotics are not common, but can include bloating and intestinal gas. They are felt to be safe with rare side effects. They should be avoided in critically ill patients and those with severe suppression of their immune system.

In patients with chronic conditions, it is felt safe to continue probiotics long term. In patients with short term conditions, such as gastroenteritis, the probiotic should be continued through the period of illness and then stopped.

In summary, probiotics are safe and can improve symptoms in some diseases. It appears that not all probiotics are alike and that different strains are needed for different diseases. They are safe in patients who are not critically ill and are generally used as a supplement to conventional therapy. As research continues, the mystery of the intestinal microbiota will gradually be unlocked and potentially the ability to correct the dysbiosis on the intestinal tract.


Dr. Peller – Southside Medical Clinic
For information or to schedule an appointment:
715-830-9990  |  www.southsidemedicalclinic.com
Dr. Peller sees patients in Eau Claire, Chippewa Falls and Cumberland.