Walk into any pharmacy or health food store and you will find the shelves brimming with probiotic supplements and foods, such as yoghurt, spruiking their health benefits.
In addition, an increasing number of people are experimenting with home fermenting, brewing up their own concoctions of probiotic consumables, such as kefir, sauerkraut, kimchi, miso soup and kombucha.
But what are probiotics? How do they differ from prebiotics? Do you need both?
Probiotics and prebiotics: what’s the difference?
Probiotics are generally thought of as the “good” bacteria in the body.
Strains of lactobacillus and bifidobacterium bacteria are the most commonly used probiotics.
Prebiotics are non-digestible food fibres that promote the growth of already-present gut bacteria. They’re found in Jerusalem artichokes, bananas, asparagus, leeks, chicory, onions, garlic, apple skins and wholegrains, such as wheat, rye, barley and oats.
“It’s a bit like your garden,” Simone Austin, an accredited practising dietitian and spokesperson for the Dietitians Association of Australia, said.
“Imagine the probiotics are the seedlings that you’ve planted. If you leave them without any food or care, they’ll die. You need to feed them with prebiotics.”
“Sometimes people think they just need probiotics and don’t worry about prebiotics, but you have to have both.”
Ms Austin said people who eat plenty of vegetables are likely to be getting enough prebiotics. Good sources include asparagus, onion and cabbage – which can sometimes also cause bloating. So, it’s important to introduce them to your diet slowly.
“For some people, that bloating – especially if the nervous system is quite sensitive – can cause pain,” Ms Austin said. “If you have this problem, you need to find a tolerance level so you can still eat some of them and not cut them out completely.”
What are the health benefits?
Sydney gastroenterologist Dr Katie Ellard said probiotic-rich foods could improve gut health.
“It’s thought that prebiotics help feed the good bugs, so to speak, as well as fermenting in the gut and producing short-chain fatty acids in the gut, which might reduce inflammation,” Dr Ellard said.
Some research shows a diet rich in prebiotics and probiotics might hold the secrets to a longer life. Researchers at McGill University in Canada who fed fruit flies a combination of probiotic and prebiotic supplements found the insects lived 26 days longer than those without supplements. They also showed reduced signs of ageing, inflammation and oxidative stress.
Other studies have shown that probiotics can help cure coughs and colds. However, consumer advocacy group Choice said the evidence did not stack up.
“Probiotics are popularly thought to reduce the risk of upper respiratory tract infections via their effects on the immune system,” Choice said.
“While some studies have found this to be the case, a large systematic review of the studies considered the overall quality of evidence low, with criticisms about the way the research was conducted, inconsistent results, or for being funded by probiotic companies, and therefore at risk of bias.”
Increase your intake the natural way
The best way to increase your intake of probiotics and prebiotics is through healthy food, rather than supplements, Dr Ellard said.
“I stress to patients there are no long-term convincing studies that prove there is benefit in spending money on probiotics,” she said.
Ms Austin said anyone considering taking a supplement should check the recommended dosage on the label. Generally speaking, at least 10 billion colony-forming units (CFU) is needed to have an effect, she said.
In Australia, Food Standards Australia New Zealand regulates probiotics and prebiotics.
However, Dr Ellard said there was no such thing as “one-size-fits-all” when it comes to probiotic products.
“People have different faecal microbiota and also have different symptoms,” she said.
“I ask my patients to consider sauerkraut, kombucha, kimchi and kefir, which are all pretty easy to obtain and relatively cheap compared to probiotics [supplements].”