Vitamin A

This volume is the newest release in the authoritative series issued by the National Academy of Sciences on dietary reference intakes (DRIs). This series provides recommended intakes, such as Recommended Dietary Allowances (RDAs), for use in planning nutritionally adequate diets for individuals based on age and gender. In addition, a new reference intake, the Tolerable Upper Intake Level (UL), has also been established to assist an individual in knowing how much is "too much" of a nutrient. Based on the Institute of Medicine's review of the scientific literature regarding dietary micronutrients, recommendations have been formulated regarding vitamins A and K, iron, iodine, chromium, copper, manganese, molybdenum, zinc, and other potentially beneficial trace elements such as boron to determine the roles, if any, they play in health. The book also: Reviews selected components of food that may influence the bioavailability of these compounds. Develops estimates of dietary intake of these compounds that are compatible with good nutrition throughout the life span and that may decrease risk of chronic disease where data indicate they play a role. Determines Tolerable Upper Intake levels for each nutrient reviewed where adequate scientific data are available in specific population subgroups. Identifies research needed to improve knowledge of the role of these micronutrients in human health. This book will be important to professionals in nutrition research and education.

This book shows how vitamin A deficiency – before the vitamin was known to scientists – affected millions of people throughout history. It is a story of sailors and soldiers, penniless mothers, orphaned infants, and young children left susceptible to blindness and fatal infections. We also glimpse the fortunate ones who, with ample vitamin A-rich food, escaped this elusive stalker. Why were people going blind and dying? To unravel this puzzle, scientists around the world competed over the course of a century. Their persistent efforts led to the identification of vitamin A and its essential role in health. As a primary focus of today’s international public health efforts, vitamin A has saved hundreds of thousands of lives. But, we discover, they could save many more were it not for obstacles erected by political and ideological zealots who lack a historical perspective of the problem. Although exhaustively researched and documented, this book is written for intellectually curious lay readers as well as for specialists. Public health professionals, nutritionists, and historians of science and medicine have much to learn from this book about the cultural and scientific origins of their disciplines. Likewise, readers interested in military and cultural history will learn about the interaction of health, society, science, and politics. The author’s presentation of vitamin A deficiency is likely to become a classic case study of health disparities in the past as well as the present.

This volume is the newest release in the authoritative series of quantitative estimates of nutrient intakes to be used for planning and assessing diets for healthy people. Dietary Reference Intakes (DRIs) is the newest framework for an expanded approach developed by U.S. and Canadian scientists. This book discusses in detail the role of vitamin C, vitamin E, selenium, and the carotenoids in human physiology and health. For each nutrient the committee presents what is known about how it functions in the human body, which factors may affect how it works, and how the nutrient may be related to chronic disease. Dietary Reference Intakes provides reference intakes, such as Recommended Dietary Allowances (RDAs), for use in planning nutritionally adequate diets for different groups based on age and gender, along with a new reference intake, the Tolerable Upper Intake Level (UL), designed to assist an individual in knowing how much is "too much" of a nutrient.

The main emphasis of this text is on the biochemistry, metabolism and systemic mode of action of vitamin A. The physiological, biochemical and nutritional aspects of naturally occurring retinoids are clearly addressed. Chapters review biogenesis, absorption, storage, transport, and metabolic transformations of vitamin A. Further discussion includes vision and bacteriorhodopsin, vitamin A deficiency and hypervitaminosis A, and the vitamin A in prevention and cure of cancer.

Micronutrient malnutrition affects approximately 2 billion people worldwide. The adverse effects of micronutrient deficiencies are profound and include premature death, poor health, blindness, growth stunting, mental retardation, learning disabilities, and low work capacity. Preventing Micronutrient Deficiencies provides a conceptual framework based on past experience that will allow funders to tailor programs to existing regional/country capabilities and to incorporate within these programs the capacity to address multiple strategies (i.e., supplementation/fortification/food-based approaches/public health measures) and multiple micronutrient deficiencies. The book does not offer recommendations on how to alleviate specific micronutrient deficienciesâ€"such recommendations are already available through the publications of diverse organizations, including the U.S. Agency for International Development, the Micronutrient Initiative, World Bank, United Nations Childrens' Fund, and the World Health Organization. Instead, this volume examines key elements in the design and implementation of micronutrient interventions, including such issues as: The importance of iron, vitamin A, and iodine to health. Populations at risk for micronutrient deficiency. Options for successful interventions and their cost. The feasibility of involving societal sectors in the planning and implementation of interventions. Characteristics of successful interventions. The book also contains three in-depth background papers that address the prevention of deficiencies of iron, vitamin A, and iodine.

Vitamin A is an essential fat-soluble vitamin with a myriad of functions including cell differentiation, redox homeostasis, growth and immune functions. Systemic inflammation has been linked with oxidative stress and has been also associated with reduced serum concentrations of Vitamin A. This book examines the protective effect of Vitamin A on lung function and cancer, chronic obstructive pulmonary disease, and coronary heart disease. Also discussed is Vitamin A and its natural derivatives, the retinoids, which participate in several biological events necessary to the maintenance of tissue homeostasis, cell cycle regulation and cell differentiation and apoptosis.

Reviews the recent breakthroughs in vitamin A research. Discusses the metabolism of vitamin A; the mechanism of action of vitamin A and the provitamin A carotenoids; the role of retinoids in embryonic development, skin and epithelial cells, blood cells, vision, and reproduction; vitamin A deficiency and teratogenicity; and the anticancer role of vitamin A from an epidemiological point of view. Intended as a source of information for scientists engaged in research in the field of vitamin A.

Every aspect of immune function and host defense is dependent upon a proper supply and balance of nutrients. Severe malnutrition can cause significant alteration in immune response, but even subclinical deficits may be associated with an impaired immune response, and an increased risk of infection. Infectious diseases have accounted for more off-duty days during major wars than combat wounds or nonbattle injuries. Combined stressors may reduce the normal ability of soldiers to resist pathogens, increase their susceptibility to biological warfare agents, and reduce the effectiveness of vaccines intended to protect them. There is also a concern with the inappropriate use of dietary supplements. This book, one of a series, examines the impact of various types of stressors and the role of specific dietary nutrients in maintaining immune function of military personnel in the field. It reviews the impact of compromised nutrition status on immune function; the interaction of health, exercise, and stress (both physical and psychological) in immune function; and the role of nutritional supplements and newer biotechnology methods reported to enhance immune function. The first part of the book contains the committee's workshop summary and evaluation of ongoing research by Army scientists on immune status in special forces troops, responses to the Army's questions, conclusions, and recommendations. The rest of the book contains papers contributed by workshop speakers, grouped under such broad topics as an introduction to what is known about immune function, the assessment of immune function, the effect of nutrition, and the relation between the many and varied stresses encountered by military personnel and their effect on health.