Probiotic Side Effects

By Dr. Ananya Mandal, MDReviewed by Sally Robertson, B.Sc.

Probiotics are live yeasts and bacteria that are thought to confer several health benefits by restoring the natural balance of the gut flora when it has been disrupted. However, there is little scientific evidence to support this claim and research is still ongoing into the actual benefits of these “friendly” bacteria.

Some areas where researchers are concerned about the use of probiotics are described below:

Critically ill patients

Fears exist about the safety of using probiotics to treat critically ill patients. Research from the Dutch Pancreatitis Study Group showed that a preparation of six probiotics increased the death rate when used to treat patients with predicted severe acute pancreatitis.

Patients with lowered immunity

Some hospitals have found that when patients with lowered immunity develop a potentially fatal disease called lactobacillus septicemia when they are treated with probiotics.

Childhood allergy

Researchers from the University of Western Australia examined the effects of probiotic administration in children with allergies. They found that of 178 infants given either a placebo or a probiotic for the first six months of life, those who had the probiotic were at an increased risk of becoming sensitive to allergens.

Another concern regarding probiotics is the fact that a big difference may exist between the pharmaceutical probiotics tested in clinical trials and the probiotics found in yoghurts or supplements that advertisers claim are beneficial to health. Most probiotics used in foods do not undergo the same level of rigorous testing to meet standards of approval that medications do and it is therefore difficult to decipher whether a yoghurt or supplement contains what the label says it does or whether there is enough of the friendly bacteria to confer health benefits.
According to the 2001 definition by the World Health Organization (WHO), probiotics are “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.” However, the bacteria contained in probiotic tablets that have been freeze-dried may not even be alive.

Different strains of probiotics also have vastly different effects and it cannot be assumed that the beneficial effects seen with one strain, apply to another similar strain.

Further Reading

• All Probiotic Content
• What are Probiotics?
• Probiotic Strains
• Probiotic Research
• Probiotic Benefits