Placebos are supposed to be nothing. They’re sugar pills, shots of saline, fake creams; they’re given to the comparison group in drug trials so doctors can see whether a new treatment is better than no treatment. But placebos aren’t nothing. Their ingredients may be bogus, but the elicited reactions are real. “The placebo effect is in some way the bane of the pharma industry’s existence because people have this nasty habit of getting better even without a specific drug,” says David Spiegel, a psychiatrist at Stanford University School of Medicine. It all boils down to ... (p. 26)

The gas well-known for its smell of rotten eggs is, recent studies show, a ubiquitous concoction in the body. New studies suggest that the hydrogen sulfide occurring naturally inside us can be both friend and enemy to our health. (p. 152)