Yogurt, for instance, dates back to at least 5000 B.C., and in Korea, kimchi — fermented vegetables — has also been consumed for thousands of years.
Today, however, live microorganisms are added to a range of products advertised as providing a wide array of medical benefits.
Creative marketing and a general fascination for gut bacteria have combined to create a huge market for probiotics.
Perhaps surprisingly, to sell a product that contains live microorganisms there is no legal requirement to provide evidence that it works or, importantly, that it is safe.
