When Dr. Rishi Manchanda asks his patients, “Where do you live?” he’s looking for more than an address. He has seen a pattern. Those who come to him for help often live in conditions of environmental stress; molds, pests, and toxins that are making them sick. So Dr. Manchanda has become an advocate of what he calls Upstream Doctors. These are health care workers who, while providing urgent medical care, are working with patients and communities to get to the source of better health.

As Jesus healed those who came to Him (Matthew 4:23–24), He lifted their eyes beyond the need…