From The Economist print edition

Healthy living switches off genes that promote cancer THAT a healthy way of life can prevent cancer is well known. It is also becoming clear that clean living can help those who already have tumours to survive, and may even prevent the disease from coming back. A number of studies have shown these effects in breast cancer and colon cancer. But how they work at a molecular level remains a mystery.

One person keen to know what is going on is Dean Ornish of the University of California, San Francisco. Besides his academic job, he is the founding president of the Preventive Medicine Research Institute, a charitable foundation based in Sausalito, California—and, as he freely admits in the interests of full disclosure, an author of general-interest books on preventive medicine and a consultant for large food companies on how to make “more healthful foods”.