Five of the ten leading causes of death in the USA are clearly related to wrong food choices. Diseases of nutritional deficiencies have declined and have been replaced by diseases of dietary excesses and imbalances-problems that now lead rank among the leading causes of illness and death, touch the lives of most Americans, and generate substantial health care costs. These problems include diseases generally acknowledged to be diet related, such as heart disease, alcoholism, obesity, and diabetes as well as other common disorders not generally acknowledged to be diet-related. Changing patterns of food-related illness are recognized. The improvement in the diversity and availability of foods has been a mixed blessing with major problems emerging to negate the potential benefits.
Food is the most intimate part of the environment because food is ingested.
When something goes wrong, it makes good biological sense to look at the flow of substances through the mouth for the source of the problem. Adverse reactions to food are common and produce many disturbances by a variety of mechanisms. Diagnosing adverse reactions to food is an important task of clinical medicine and needs to be taught in medical schools. Often, the potential benefits of diet revision in the solution of health problems are ignored. Many food and nutritional issues are complex and genuinely difficult to understand.