Probiotics help to move food through the gut. Researchers are still trying to figure out which are best for certain health problems.

Probiotics help to move food through the gut. Researchers are still trying to figure out which are best for certain health problems

Many types of bacteria are classified as probiotics.

They all have different benefits, but most come from two groups: Lactobacillus and bifidobacterium. Lactobacillus may be the most common probiotic. It is found in yoghurt and other fermented foods. Different strains can help with diarrhoea and may help with people who can’t digest lactose, the sugar in milk.

Bifidobacterium is found in some dairy products. It may help ease the symptoms of irritable bowel syndrome (IBS) and some other conditions. Although more research is needed, there’s encouraging evidence that probiotics may help:

  • Treat diarrhoea, especially following treatment with certain antibiotics
  • Prevent and treat vaginal yeast infections and urinary tract infections
  • Treat irritable bowel syndrome
  • Speed treatment of certain intestinal infections
  • Prevent or reduce the severity of colds and flu.

Side effects are rare, and most healthy adults can safely add foods that contain prebiotics and probiotics to their diets.

What do they do?

Some common conditions they treat are:

  • Irritable bowel syndrome
  • Inflammatory bowel disease (IBD)
  • Infectious diarrhoea (caused by viruses, bacteria, or parasites)
  • Antibiotic-related diarrhoea. Some research indicates they can also help with:
  • Skin conditions, like eczema
  • Urinary and vaginal health
  • Preventing allergies and colds
  • Oral health.


Prebiotics are not the same as probiotics. The term ‘prebiotics’ refers to dietary substances that favour the growth of beneficial bacteria over harmful ones. Synbiotics refers to products that combine probiotics and prebiotics. Prebiotics are nondigestible  carbohydrates that act as food for probiotics. When probiotics and prebiotics are combined, they form a synbiotic. Fermented dairy products, such as yoghurt and kefir, are considered synbiotic because they contain live bacteria and the fuel they need to thrive. Probiotics are found in such as yoghurt, while prebiotics are found in whole grains, bananas, onions, garlic, honey and artichokes. In addition, probiotics and prebiotics are added to some foods and available as dietary supplements.

When prescribing probiotics, one must consider the probiotic formulation, including live, dead, compounded preparations or their products, the effective dose to use and the type of disease targeted. One cannot extrapolate specific actions or doses of a given probiotic and generalise these properties to other doses or strains of probiotic bacteria.