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? We are surrounded by bold claims and quick fixes for 'boosting' our immune health. But one thing the science is clear on is that everyone's immune system is completely unique - what is good for one person may not work well for another. So 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? In this expert guide, world-leading immunologist Daniel M. Davis examines the effects of stress, diet, age, exercise, the microbiome and more on the immune system, punctures the key myths, sorts the fact from the fiction and equips us to make informed choices for ourselves.