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 these claims and research is still ongoing into the actual benefits of these “friendly” bacteria.

Most probiotics that have been studied for their beneficial effects are from the Lactobacillus genus. These bacteria have been studied for their beneficial effects in conditions such as antibiotic-associated diarrhea, inflammatory bowel disease and irritable bowel syndrome.

Lactose intolerance

Lactose intolerance is a common condition of the gut caused by an inability to digest lactose, the sugar present in milk and dairy products. People with this condition are deficient in the enzyme lactase, a protein produced in the small intestine to help break down lactose. Some studies suggest that Lactobacillus acidophilusproduces lactase, therefore restoring the breakdown and absorption of lactose.

Persistent diarrhea

Lactobacilli have also been shown to benefit patients with persistent diarrhea. Some studies suggest the strain Lactobacillus rhamnosus GG improves traveller’s diarrhea and gastroenteritis caused by a rotavirus in children. However, the evidence is still not strong enough to support treatment recommendations.

Helicobacter pylori

Some strains of lactic acid bacteria may be useful for treating Helicobacter pylori infection, which can lead to peptic ulcer, although this has not yet received regulatory approval as a treatment.

Antibiotic-associated diarrhea (AAD)

Some evidence does support that Lactobacillus rhamnosus GG does prevent AAD in children when administered in high doses. Antibiotics tend to eliminate many protective bacteria in the gut, which can cause diarrhea. Replenishing the gut with probiotics is thought to prevent growth of the harmful bacteria that produce toxins and cause illness.

Irritable bowel syndrome

Probiotics may help reduce some of the symptoms of irritable bowel syndrome such as bloating, flatulence and pain. Although this is supported by a 2010 Cochrane review, the exact benefits are still not clear and it is not understood which strain or species of probiotic is the most effective.