What Your Gut Bacteria Say About You

OK, you don't like yogurt. Or kimchi, tempeh, sauerkraut or other "friendly-flora" foods. But if your housemates eat them—good news! Their healthy brain-boosting microbes have probably taken up residence in you. "A number of gut microbes form so-called spores—environmentally hyper-resistant cells that help to colonize them," explains James Scott, professor of occupational and environmental health at the University of Toronto. They're found on surfaces and in dust; we inhale and ingest them.