The terms probiotics and prebiotics are appearing on more items in supermarket aisles all the time. Both words, their placement and the products they adorn, imply they’re good for you, that more of these bacteria will help you in some way. But there’s actually scant evidence for such claims.
Let’s start at the beginning: a probiotic is something full of bacteria expected to take up residence in your gut, while a prebiotic promotes the growth of already-present gut bacteria.
Before you buy probiotics, you need to know whether they survive the perilous journey through the stomach and into the lower gut. And whether the bacteria have a measurable impact on your health once they reach their destination.
Sadly, this information is not available because we haven’t done the research to find out. But new European food regulations are starting to push manufacturers to provide evidence for probiotics’ advertised health benefits.
What They’re Supposed to Do
When you consume a probiotic, you’re eating a particular strain of bacteria that you – and the product’s manufacturer – consider helpful. Many bacteria are killed by the acidic conditions in the stomach but a small number survive and may make it to the lower gut – the colon or large intestine.
Once at their destination, these bacteria need to establish themselves. But it’s a jungle down there, with many competing species of bacteria and scarce resources. In order to survive, new arrivals need food and this is where the prebiotics come in.
Prebiotics feed gut bacteria and are not usually digestible. One example of a prebiotic is a sugar contained in many beans called raffinose, which the gut is not equipped to use. It’s the basis for the well-known – and entirely true – story that beans make you fart. Specifically, the bacteria in your gut that like raffinose also like to produce gas when they eat it.
Prebiotics nurture specific types of bacteria already present in your lower gut. As with the probiotics, the idea is that nurturing these bacteria and increasing their numbers will provide a health benefit.
Regulatory Hurdles
Both probiotics and prebiotics are generally sold as food products. To put a health claim on a food label in Europe requires strict scientific evidence.
In 2006, the European Union adopted a new set of regulations that defined the terms probiotic and prebiotic as making specific health claims. The directive effectively acted as a ban on using these words on packaging because none of the products using the words has the evidence to back up their health claims.
