The "gut flora", an ecosystem of bacteria and other microorganisms in the intestines, plays an important role in human health. Researchers say improving the balance of the gut flora can boost our immunity. In Japan, medical experts give premature babies bifidobacteria to strengthen their weak immune systems. Japanese hospitals give patients drinks rich in so-called "good" bacteria to fight infections after cancer surgery. We'll also share some exercises to keep the intestines in good shape.
