Probiotic supplements have no effect

Probiotic supplements given to elderly patients on antibiotics appear to have no effect on the incidence of diarrhoea, a common and sometimes life- threatening side effect of using antibiotics for many elderly patients, reveals a new study published in the Lancet.

While some previous research has suggested that probiotic preparations — similar to those available in popular probiotic yoghurt drinks — might reduce the incidence of antibiotic- associated diarrhoea ( AAD), and prescribing probiotics for elderly patients on antibiotics has become routine practice in some institutions. The mechanism by which antibiotics result in diarrhoea is not well understood, but is thought to be due to antibiotics disrupting the body’s normal complement of socalled “friendly bacteria” — the population of bacterial organisms ( gut flora or microbiome) which live in any healthy person’s digestive system. It has been suggested that probiotic supplements might be able to reduce the incidence of AAD by restoring the gut flora to its normal constituency after disruption by antibiotics.

A team of researchers led by Professor Stephen J. Allen of Swansea University in Swansea, UK, recruited nearly 3,000 people to the Placide trial, which took place in five hospitals located in south Wales and northeast England. Study participants were all hospital inpatients aged 65 or over — the age group for which AAD tends to cause most problems — and had been prescribed one or more antibiotics.

Around half of the study participants were asked to take one capsule containing a fixed dose of live bacteria ( two strains of Lactobacillus acid ophilus, Bifidobacterium bifidum, and Bifidobacterium lactis) per day for 21 days, and between antibiotic doses where possible, while the remaining study participants in the control group received an identical placebo capsule, with the same dosing instruction. The researchers analysed stool samples from around half of the patients who experienced diarrhoea.