Vitamins: Their Role in the Human Body
George F. M. Ball
Format: PDF / Kindle (mobi) / ePub
This single-source reference draws together the current knowledge of the vitamins' biological properties in the context of human nutrition. Vitamins are co-enzymes, antioxidants or precursors of hormones and are therefore involved in a great many biochemical and physiological processes. They play a vital role in the maintenance of health, and there is evidence that dietary sources of vitamins have beneficial effects in the prevention of heart-related diseases, bone diseases and possibly cancer.
Following introductory chapters on historical and nutritional aspects of vitamins, the next four chapters cover relevant and detailed aspects of physiology and functional anatomy, biochemistry, immunology and the regulation of protein synthesis by nuclear hormone receptors. These background chapters, supported by a glossary of terms, provide the scientific principles upon which vitamin functions are based. The following thirteen chapters deal with each vitamin in turn. Subject areas include chemical structure, intestinal absorption, transport, metabolism, biochemical and physiological actions, immunoregulatory properties, deficiency-related diseases and potential toxicity. An extensive bibliography refers the reader to the original research literature.
Vitamins is aimed at nutritionists, biochemists, physiologists and physicians whether they be researchers, teachers or students. Food scientists, food technologists and many others working in the health professions will also find much of use and interest in the book. The inclusion of the theoretical principles in the background chapters makes the book an ideal starting point for those working outside the area who need a solid overview of the subject.
being found in tissues of the reproductive tract. They have an additional role in delivering their respective ligands to specific binding sites within the nucleus. CRABP-I also sequesters 07ballch7.indd 138 retinoic acid, in excess of cellular needs, and facilitates its catabolism into a variety of polar metabolites. Tissue distribution of CRBP-II and CRABP-II is much more restricted. The former is found mainly in the enterocytes of the small intestine, where it is involved in the metabolism of
marine fish and carnivores (e.g. bear and dog). Acute toxicity results from the ingestion of a single or several closely spaced very large doses of vitamin A, usually more than 100 times the recommended intake. Such doses produce a variety of toxic signs that include vomiting, severe headache, dizziness, blurred vision, muscular incoordination and malaise. These signs are usually transient and disappear within a few days. In acute hypervitaminosis A, the excess retinol circulating in the
putative molecules are transmitted to neighbouring cells 03ballch3.indd 62 06/07/04, 14:19:25 Background physiology and functional anatomy by diffusion through gap junction channels and never leave the intercellular space. Many studies have shown that intercellular communication is necessary for normal growth regulation and that cell proliferation occurs when intercellular communication is decreased. Inhibiting the gap-junctional flow of growth-controlling factors leads to neoplastic
biosynthetic pathways or excretion pathways that lead to the elimination of nitrogenous waste products. 01/07/04, 14:16:18 Background biochemistry COO– COO– + CH2 + aminotransferase B6 R C O CH2 + HC NH3 HC NH3 CH2 COO– CH2 α-Ketoglutarate Amino acid Deamination Deamination reactions involve the removal of an amino group with no direct transfer to another compound. Figure 4.6 shows the oxidative deamination of glutamate catalysed by glutamate dehydrogenase, which takes place in
been established. 4.5.7 Development of the atherosclerotic lesion Initiation Plasma LDL enters the subendothelial space of the arterial intima where it is trapped in microenvironments secluded from plasma antioxidants. LDL lipid is mildly oxidized to minimally oxidized LDL through the action of resident vascular cells. The modified lipoprotein induces local vascular cells to produce 01/07/04, 14:16:25 86 Vitamins: their role in the human body MCP-1, which attracts circulating monocytes, and