ABSTRACT
Living organisms consist mainly of hydrogen, carbon, nitrogen, and oxygen. The concentration of these elements in biological matter can be expressed in grams per kilograms, and in humans they are required in grams per day in the forms of fat, sugars, proteins, water, vitamins, and oxygen. Bioavailability depends on the chemical form of the element in the food, the pH of the stomach contents, and the presence of and interactions with other nutrients in the food. Scientists from a large number of disciplines in the medical and natural sciences focus on the essentiality of the different elements. Strong indices of the essentiality of chromium originate from three studies in man on parenteral nutrition. As trace and mineral elements are transferred up the soil-plant-animal-human food chain, geographical differences account for large variations in the mineral content of foods. Clinical and experimental studies suggest that zinc deficiency plays an important role in the pathogenesis of several diseases.
