Update: Probiotics for treating acute infectious diarrhoea

08 Dec 2020

Do probiotics help to treat acute infectious diarrhoea?

What is the aim of this review?

Acute infectious diarrhoea is a major global disease that particularly affects people in low‐ and middle‐income countries. We wanted to know if taking probiotics is helpful in shortening the time taken for symptoms to resolve. We searched for studies that looked at the use of probiotics in people with acute diarrhoea. We looked for studies in which the treatments people received were decided randomly; these usually give reliable evidence.

Key messages

Probiotics may not affect how long acute diarrhoea lasts. We do not know if they can shorten the time to recovery from diarrhoea. We need reliable evidence from further studies to determine whether probiotics help treat acute infectious diarrhoea.

What was studied in the review?

”Diarrhoea” is the name for frequent bowel movements or the passing of unusually soft or watery faeces. Infections of the gut by bacteria, viruses, or parasites cause acute diarrhoea and are most often spread through water contaminated with faeces. Acute diarrhoea usually improves within a few days. However, in severe acute diarrhoea, water, salts, and nutrients that may be lost from the body are substantial, causing dehydration and even death. Treatments for acute diarrhoea aim to prevent or reverse dehydration, speed up recovery time, and shorten the time that a person may pass the infection to others.

Probiotics are live bacteria and yeasts that are thought to restore the natural balance of bacteria in the gut (intestines) when this has been disrupted by illness or treatment. Probiotics are often described as "good" or "friendly" bacteria; they may be present in yoghurts or taken as food supplements. In acute infectious diarrhoea, probiotics may act against the harmful microbes that are causing diarrhoea, help the gut to fight them, or reduce inflammation and damage to the gut.

What are the main results of the review?

We found 82 studies in 12,127 people (mostly children) with acute diarrhoea. Only 26 studies took place in countries that had high numbers of deaths (of any cause) among adults and children.

These studies compared the effects of different types of probiotics with no additional treatment or with a placebo (dummy) treatment. We were interested in:

• how many people had diarrhoea longer than 48 hours; and
• how long, on average, the symptoms of diarrhoea lasted.

There were many differences in the ways these studies were designed and carried out. Studies used different definitions of "acute diarrhoea" and "the end of diarrhoea symptoms," and they tested many different probiotics. Therefore, we could not include the results of all studies in our analysis.

We did not detect a difference between taking a probiotic and taking a placebo or no additional treatment in the number of children who had diarrhoea longer than 48 hours (two studies in high‐income countries; 1770 children). We are uncertain whether taking probiotics affects the length of time that the symptoms of diarrhoea last (six studies; 3058 people). These findings were not affected by age, nutritional and socioeconomic status, region, or rotavirus infection of participants, nor by whether they were taking antibiotic medicines or zinc supplements.

Taking probiotics may not have affected:

• how many people had diarrhoea longer than 14 days (nine studies; 2928 people); or
• how many people were admitted to hospital with diarrhoea (six studies; 2283 people).

It was unclear whether taking probiotics shortened the time spent in hospital compared with taking a placebo or no additional treatment (24 studies; 4056 people). Few studies reported on any unwanted effects of probiotics; no serious unwanted effects were reported among people who took probiotics.

How reliable are these results?

Previous published editions of this review drew conclusions from the many small studies in this field and indicated an effect.

This new analysis shows that in this topic there is publication bias, with small studies demonstrating a positive effect more likely to be published, which skews the results. This fresh analysis takes this into account.

How up‐to‐date is this review?

We included evidence published up to 17 December 2019.

Diarrhoea Maternal and child health