The relationship between nutrition and health has changed dramatically during the past 50 years. As recently as the 1940s, diseases, such as rickets, pellagra, scurvy, beriberi, xerophthalmia, and goiter (caused by a lack of or deficiency in vitamin D, niacin, vitamin C, thiamin, vitamin A, and iodine, respectively), were common in the united states and throughout the world. Thanks to an abundant food supply, fortification of some foods with critical trace nutrients, and better methods of improving the quality of foods, such deficiency diseases have virtually been eliminated in developed countries. Nutrition deficiencies are rarely reported in the united states, and when they do occur, they are usually associated with poverty, high-risk conditions (such as premature birth or alcoholism), and conditions related to prolonged chronic illnesses.The deficiency diseases of the past have been replaced by diseases of dietary excess and imbalance. For most americans the problem is overeating too many calories for the activity level and over consumption of fat and sodium. In the united states, 5 of the top 10 causes of death are associated with diet (heart disease, some types of cancer, stroke, non insulin dependent diabetes mellitus, and chronic liver disease). The association between diet and health is so convincing that nutrition was designated as one of the target areas in the 1979 landmark publication, Healthy people: the surgeon general’s report on health promotion and disease prevention. In the late 1970s the US senate commissioned a study on nutrition, which eventually concluded that over consumption of certain dietary components is a major concern for americans. Chief among these concerns is the disproportionate consumption of foods high in fats, often at the expense of foods high in complex carbohydrates and fiber, which are healthier. Also of concern are insufficient amounts of calcium, iron, zinc, and dietary fiber. In response to criticism of the american diet, the US department of agriculture (USDA) and department of health and human services (DHHS) established the following recommendations that are the basis for the dietary guidelines for americans :

• Eat a variety of foods.
• Balance your food intake with physical activity; maintain or improve your weight.
• Choose a diet low in fat, saturated fat, and cholesterol.
• Choose a diet with plenty of grain products, vegetables, and fruits.
• Choose a diet moderate in sugars.
• Choose a diet moderate in salt and sodium.
• If you drink alcoholic beverages, do so in moderation.