Sugar Coated: Molecular dress-up may disguise gut bacteria

Even when you think you’re alone, you’re not. Several trillion bacteria tag along within the intestines of a typical person or other mammal.

While researchers have long known that these bacteria serve beneficial functions for their hosts, such as producing vitamins and breaking down nutrients (SN: 5/31/03, p. 344: Gut Check), it hasn’t been clear why the host’s immune system doesn’t attack the microbes as foreign invaders.