Human nutrient requirements

Young, V. R., 2001 W.O. Atwater Memorial Lecture and the 2001 ASNS F resident s Lecture— Human nutrient requirements The challenge of the post-genome era, J. Nutr., 132 (4), 621-629, 2002. 

The concept of variability in human nutrient requirements among individuals of similar general characteristics must be accepted. In the words of the FAO/WHO/UNU report (1984), the recommended intake ... 

Derived plant and animal products make better use or upgrade the nutritional quaHty of already existing materials or products. Synthetic and manufactured products arose from knowledge of the functional properties of food ingredients and of human and animal nutrition that involved more precise definition of nutrient requirements for growth, reproduction, lactation, and body maintenance in both humans and domestic Hvestock. Pood products have been developed to meet human needs under abnormal environments, eg, military rations for arctic, tropical, or desert environments, and special products for astronauts ia space flights. 

Generation of data on the nutrient content of agricultural products and foods forms the basis for estimating nutrient intakes of populations via dietary surveys, nutritional labelling for consumer protection, nutrition education for consumer food choice, home and institution menu planning and food purchase, and for research in nutrient requirements and metabolism, toxicant chemical composition is used to assess effects of farm management practices, crop culture, and food processing on chemical content and implications for human health. 

Iodine is a required human nutrient and is a component of thyroid... 

Vitamin a general term for a required human nutrient. 

Water accounts for over half the body mass (55%) of the average human. Of the remaining 45%, 19% is protein, 19% is lipid, less than 1% is carbohydrate, and 7% is inorganic material. Nutrients must contain the raw materials that go into the construction of the components of the human body. In addition, nutrients must supply the necessary chemical energy and enzyme cofactors (vitamins and trace metal elements) that are required for the maintenance and growth of the human body. The human body requires nutrients such as water, amino acids, fats, carbohydrates, and major minerals in large amounts. Vitamins and trace metal elements are required in smaller amounts. 

Understanding the total nutritional needs of the human body requires a more detailed consideration of the chemical composition of different nutrients. As we have seen in Chapter 22, the body cannot synthesize many of the amino acids needed to build proteins. For this reason, the body requires proteins that contain the essential amino acids in sufficient quantities. Too little animal protein will lead to nutritional deficiencies because plant proteins do not contain an adequate supply of all the amino acids that active humans must receive from their diets. 

Calcium Effects on Zinc Bioavailability for the Rat and the Human. It should be pointed out at this juncture that the nutrient requirement of calcium for the rat is much higher than for man. In fact, the molar ratio of calcium to zinc in excess of 660 1 is recommended for rat diets, while for man the ratio is between 80 1 and 160 1. To feed rats molar ratios of calcium and zinc similar to human requirements would necessitate either a very calcium deficient diet or one containing zinc at a level well in excess of the requirement. Neither choice is nutritionally suitable for demonstrating an effect of phytate on zinc availability. 

The recommended dietary allowances (RDAs) for various nutrients arc discussed. RDAs are the quantities in the diet of all nutrients required to maintain human health. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences, and are published by the National Academy Press-The RDA values are revised periodically on the basis of new scientific evidence. 

An important problem in determining nutrient requirements and optimum diet is the definition of the criteria of health that must be met. Often relatively short-term assays of requirements based on weight gain, morbidity, and mortality, or the incidences of morphological or biochemical lesions are used as indices to establish optimum nutrition. However, if the subhuman primates are to be used effectively as a model for human nutrition, then we should consider studies into optimum nutrition for a long and vigorous life. 

RDA values are overestimates of nutrient requirements minimum quantities of nutrients required to maintain normal function and health in humans are either unknown or incompletely known. 

COENZYMES Most coenzymes are derived from vitamins. Vitamins (organic nutrients required in small amounts in the human diet) are divided into two classes water-soluble and lipid-soluble. In addition there are certain vitamin-like nutrients (e.g., lipoic acid, carnitine, and p-aminobenzoic acid) that can be... 

An example of the difference between the AI and the EAR is provided by riboflavin. Very few data exist on the nutrient requirements of very young infants. However, human milk is the sole recommended food for the first 4 to 6 months, so the AI of the vitamin riboflavin for this life stage group is based on the amount in breast milk consumed by healthy full-term infants. Conversely, the riboflavin EAR for adults is based on a number of studies in humans relating dietary intake of riboflavin to biochemical markers of riboflavin status and development of clinical deficiency symptoms. 

Since ancient times, avian eggs have been one of the most common and important foods in the human diet. Egg is considered the most complete food source from the nutritional perspective since it provides aU the nutrients required for embryo development. Egg is used not only because of its high nutritional value, which is especially important as an excellent source of nourishment for growing children, but also because... 

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