We are surrounded by bold claims and quick fixes for improving our immune systems. In this expert guide, leading immunologist Daniel M. Davis sorts the fact from fiction. Is it true that orange juice can help ward off colds? How does age affect our immune system? Is mental health really connected to inflammation? How do we separate the bogus claims from the useful advice? And given its sheer complexity, is there anything we can do to improve our immune system? World-renowned immunologist Daniel M. Davis examines the effects of stress, diet, age, exercise, the microbiome and more on the immune system, punctures the key myths, and equips us to make informed choices for ourselves.