Boosting your immunity
A dietitian and a food microbiologist talk to Lisa Salmon about the benefits of ‘good’ bacteria.
Ahealthy immune system is vital for keeping us well, and one proven way to support it is with probiotics. Many studies have found these ‘good bacteria’ can help balance gut flora, helping produce protective substances which may ‘turn on’ the immune system to fight off bugs.
Glenn Gibson, Professor of food microbiology at University of Reading, and Dr Carrie Ruxton, a dietitian for the Health and Food Supplements Information Service (www.hsis.org) told us more about the friendly bacteria that live in our intestines, stomach and gastrointestinal tract…
WHAT ARE PROBIOTICS?
The World Health Organisation defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”. Ruxton says: “Probiotics are live ‘friendly’ bacteria in food or supplement form that can alter the balance of our own gut bacteria – assuming they reach the gut intact.”
WHAT ARE THE HEALTH BENEFITS OF PROBIOTICS?
“Lots,” says Gibson. “These include improved protection against gastroenteritis, reduced inflammation (hence the link to Covid), and boosting immunity – being harmless microbes, they’re good at stimulating non-specific immunity in the gut. Specific diseases like IBS (irritable bowel syndrome) and
IBD (inflammatory bowel disease) have been looked at and there’s currently immense interest in obesity and gut-brain interactions (cognitive function).”
CAN YOU GET PROBIOTICS IN FOOD?
Probiotics are found in many fermented foods, including kefir (fermented milk), kombucha (fermented sweet tea), kimchi (spicy fermented cabbage), tempeh (fermented soya bean patties), miso (fermented soya bean paste) and sauerkraut (fermented cabbage), as well as yoghurt.
“Probiotics can also be found in supplements and special drinks such as Yakult,” says Ruxton. “The most accessible prebiotics are tea, onions, garlic and leeks.” Gibson explains that prebiotics are like fertilisers for live probiotic microbes already in the gut.
WHO SHOULD TAKE PROBIOTICS?
Ruxton says UK diets tend to be low in fibre, fruit and vegetables and high in animal protein, and our nutritional intake during infancy may also play a role. “However, people who are eating their five-a-day fruit and veg, and getting two to three daily servings of fibre-rich foods like wholegrain bread, pasta and rice, or high-fibre breakfast cereal, plus a few servings of fermented foods a week, should have a healthy gut microbiota. Everyone else should consider adapting their diets, or taking a probiotic supplement.”
ARE SUPPLEMENTS NEEDED TO GET ENOUGH PROBIOTICS?
Gibson says the answer to this is yes, but Ruxton says it’s easy to get enough in the diet, ensuring you eat plenty of dietary fibre from wholegrains, fruit, vegetables, legumes and yoghurt.
“Supplements, or probiotic drinks, can be useful,” she agrees, “for example, if you’ve had a recent course of antibiotics, a viral illness, or are planning to travel abroad and want to avoid a dodgy tummy.”
CAN PROBIOTICS CAUSE ANY PROBLEMS?
Ruxton says people who are, for example, taking immunosuppressant drugs linked to organ transplants, should avoid probiotics because even ‘good’ bacteria, which would be harmless in most people, has the potential to cause infection in those with a suppressed immune system. “Apart from that, probiotics don’t cause harm, even in young children,” she says. “In fact, foods containing natural probiotics have been eaten by people around the world for thousands of years.”