Gastrointestinal infections and diarrhoea. The strongest evidence for taking probiotics to improve health is linked to their role in preventing and treating diarrhoea.
In a review of 63 studies probiotics taken with rehydration powders were found to reduce the frequency and duration of diarrhoea. If you suffer a bout of gastroenteritis take probiotics daily for about a month.
Irritable bowel syndrome (IBS). It is estimated that between 10 and 20 per cent of adults in the UK suffer with IBS, which can develop after a bout of gastroenteritis.
The main symptoms are bloating, stomach cramps, flatulence, diarrhoea and constipation.
In many IBS sufferers the microbiome is out of balance so restoring the microbiota (gut flora) can help to relieve uncomfortable symptoms.
A review of 14 trials at the University of Oxford found probiotics played a role in alleviating some of the symptoms of IBS, including pain, flatulence and bloating.
Lactose intolerance. This condition occurs when the body is unable to digest lactose, the main sugar in milk. It is caused by a lack of the enzyme lactase which breaks down lactose.
It is often a temporary condition, occurring after a stomach bug that resulted in diarrhoea.
Symptoms include bloating, cramping, loose stools and flatulence. Research shows that lactobacillus acidophilus helps to produce the enzyme lactase and so aid digestion and absorption of lactose. Try Quest Acidophilus Plus, £8.89 for 60 capsules.
Inflammatory bowel disease. According to a review of 41 studies there is not yet enough evidence to support the use of probiotics in Crohn’s disease. But their use looks far more promising for people with ulcerative colitis.
Constipation. A change in bacteria in the gut can have the unwelcome effect of slowing movement in the bowel.
A review of 11 trials found taking probiotic supplements reduced the amount of time it took for food to pass through the digestive tract with the greatest effects seen in older adults and those who were constipated.
Bifidobacterium lactis strains seemed to have the greatest effect.
Coughs, colds and infections. Around 70 per cent of our immune system is in our digestive system and taking probiotics has been linked with a lower incidence of coughs, colds and infections.
Chinese researchers looked at 10 different studies and found people taking probiotics had a reduced incidence of upper respiratory tract infections compared with those taking a placebo. They were also less likely to need antibiotics.
Obesity. Emerging research suggests there is a link between the balance of microbes in our gut and our weight.
Much of the work is still in its early stages but studies show obese people tend to have a poor-quality microbiome compared with slim people.
We don’t yet know whether this is a cause or consequence of obesity but studies do show weight loss or weight gain can affect the balance and composition of gut bacteria.