Nutricion

Nutritional Requirements

The human body requires about 40 nutrients, which are considered essential if the body can not synthesize it and if an identifiable deficiency causes abnormalities disappear when you correct their deficiency. Necessary nutrients include essential amino acids, water soluble and fat soluble vitamins, minerals and essential fatty acids.

The body also needs adequate energy substrate, a small amount of metabolizable carbohydrate, indigestible carbohydrates (fiber), additional nitrogen and water. Most of the nutrients needed are dangerous when consumed in excessive amounts. Consequently may set a limit of acceptable intake.

Nutritional requirements are defined as the average daily amounts of nutrients you should consume a population group. In USA, the nutritional requirements the most widely used are the recommended dietary allowance (RDA) developed by a subcommittee of the Food and Nutrition Board of the National Academy of Sciences (Food and Nutrition Board of the National Academy of Sciences). Have been established RDA for energy and protein, water-soluble vitamins: thiamine, riboflavin, niacin, vitamin B6, folic acid, vitamin B12 and vitamin C. Fat-soluble vitamins A, D, K, and minerals: calcium, phosphorus, magenesio, iron, zinc, iodine and selenium.

The RDR exceed the actual requirements of most individuals in the population because they are attached to two above the estimated average requirement. Consequently, a lower dietary intake of the RDA of a specific nutrient is not necessarily inappropriate for a particular person (although it increases the risk of inadequate intake).

For most clinical situations, it is considered that two thirds of the RDAs are adequate nutritional intake. The RDA for energy are treated in different ways. As energy needs vary so much between individuals, the RDR Committee has estimated the average needs of the population more than the recommended intakes for individuals.

One half of the population will need more energy than the RDR and the other half will require less. The nutritional requirements not only vary from one person to another but from one day to the next in a given individual. They also differ with age, sex, body size, and during pregnancy and lactation. RDR has been developed different for different sex and age groups.

They also vary with clinical circumstances, including preterm birth, aging, metabolic disorders, infections, chronic diseases, medications, physical activity, or extreme weather and through ingestion. The RDR do not cover these situations are only indicated for healthy populations.

Sources: Current Medical Diagnosis & Treatment 1992