However, he is most definitely not a believer in the wide range of supplements and simple answers often proffered in self-help books. Somewhat endearingly, at times the argument made by the complex science that he cites boils down to saying, with Michael Pollan (or your grandmother), something as basic as “Eat fresh food.” He also argues for a strenuously regular (and regularly strenuous) schedule, with set times for exercise and relaxation. But he explains the reasons in terms of physiology, science and a strong conviction that the body can be understood only as a very complex system. In other words, this is a self-help book that avoids magic bullets and quick fixes, arguing instead for a recognition of the body’s intricate systems of homeostasis and self-repair.

The strength of “The End of Illness” is that it brings medical research and a sophisticated understanding of the complexity of human physiology to bear on explaining practical methods for preventing disease and improving health. In fact, Agus provides a formal series of health rules. He wants his readers to take charge of their medical details and understand individualized risk and individualized therapy: “Know as much about yourself as possible through the use of technology, including how you metabolize drugs.” He wants us to understand the potential importance of the body’s inflammatory response, which, he argues, is at the root of much pathology: “Take charge of hidden, sneaky sources of chronic inflammation that can trigger illness and disease by wearing comfortable shoes daily, getting an annual flu vaccine, and asking your doctor why you’re not on a statin and baby aspirin if you’re over the age of forty.” And he wants readers to assist their bodies’ homeostatic and anti-inflammatory systems by avoiding stress and shocks to the system: “Keep a strict, predictable schedule 365 days a year that has you eating, sleeping, and exercising at about the same times day in and day out.”

Though some of the rules are quite straightforward, the book is at its best when it takes on complexity. Agus’s discussion of vitamin D is both sane and detailed, tracing the basics of vitamin D metabolism and then examining the many claims made in recent years about the dangers of vitamin D deficiency and the potential curative (not to say, panacea) effects of supplementation. This vitamin, important in regulating calcium and bone health, is also involved in many other physiologic processes, from cell growth to inflammation. “But despite its role in many of the body’s vital functions,” Agus writes, “we must be careful about making broad statements about vitamin D and its link (‘associations’) to various illnesses and disease. Despite thousands of studies, there’s not a lot of strong research showing consistent benefits from vitamin D supplementation.”