NUTRITIONAL BIOCHEMISTRY. 2nd. edition

Abstract

relevant. The section on starvation reveals that the body may suffer from signs of vitamin A deficiencye ven though substantiala mountso f the vitamin are storedin the liver. The section on fiber explains how an undigestible nutrient supplies vital energy to cells of the human body. Someo f the dreadedn utritional diseaseso f the pas t - - such as scurv~ pellagra, and perniciOusa nemiam are discussedin this book. Suchc ontemporaryp roblems as infectious diarrhea, xerophthalmia, protein/energy malnutrition, and folate deficiency are discussed, as are diabetes and cardiovascular disease, two of the most significantn utrition-relatedd iseasesT. he last two conditions can be controlled in part by dietary intervention. This book stressesth e importanceo f nutritional interactions.S omen utrientsa re closely relateda nd usually discussedt ogether.S omea re antagonistict o eacho ther, whereaso thersa ct synergistically. Exampleos f uniquely relatedn utrientsa re bean and rice protein, saturateda nd monounsaturatedfa tty acids, folate and vitamin B12, vitamin E and polyunsaturatedfa tty acids,a nd calcium and vitaminD . Some closely relatedb iological moleculesa re discussed,in cluding insulin and glucagon, cholecystokinin and secretin, and low- and high-density lipoproteins. Interactions involving multiple organ systemsa nd multiple cell types are stressedM. ore emphasis is placed on interorgan relationships than in typical biochemistry textbooks. Drugs that influence nutrient metabolism are discussed in various sections. These drugs include lovastatin, pravastatin, omeprazole, dilantin, methotrexate, allopurinol, warfarin, furosemide,t hiouracil, and diphosphonate.A lcohol is also discussed in this context because, depending on its intake, it functions as a food, drug, or toxin. The recommendedd ietarya llowances (RDAs) for various nutrients are 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 Academyo f Sciences,a nd are publishedb y the National AcademyP ress. The RDA values are revised periodically on the basis of new scientific evidence. RDAs are used to define a relationship between various human populations and the nutrients required by the human body at various stages of life. They are intended to serve as a basis for evaluating the adequacy of diets of groups of people rather than of individuals. A comparison between the RDA for a specific nutrient and individual intake of that nutrient can indicate the probability or risk of a deficiency in that nutrient. The actual nutritional status with respect to the nutrient can be assessedo nly by appropriatet ests.T heset ests areu sually of a biochemical nature, but also may be hematological or histological. Nutrient RDAs have been determinedf or men, women,a nd children of different ages.I n most cases,t he RDA differs with body weight and, in some cases,w ith gender.F or convenience,R DA values are sometimese xpressedi n terms of an ideal or reference subjecst uch as "the 70-kg man" or "the 55-kg woman." The current RDAs for all nutrients are listed on the inside back cover. RDAs have not been set for a number of required or useful nutrients. The estimated safe and adequate intakes of these nutrients establishedb y the Food and Nutrition Board, are listed on the inside front cover.