Although we have no good definition of ‘health’, all people have their own ideas of whether they are healthy or not. Based on personal experience and knowledge each person comes to accept that within themselves there is a normal range of feelings and performance, departure from which could be considered abnormal or unhealthy. Despite the many amazing technological advances made over recent decades it cannot be said that access to advanced medical care is the main determining factor in the healthiness or otherwise of a society. Even in these modern times most diseases and health problems are non-curable in the strict sense, and the scope for effective prevention of disease is more limited than some enthusiasts suggest. Individuals must appreciate the limitations of modern medical care and, while seeking to use the care available to best possible effect, accept that the responsibility for trying to prevent major disease rests in their own hands. In this book we have tried to present a balanced and realistic picture of the many factors that must be taken into account if optimum disease prevention and health maintenance are to be achieved. The health of your family is your responsibility. An understanding of what can go wrong, how it can be prevented or how it can best be coped with can only be helpful to you.