The Fat Soluble Vitamins

The subject for a volume on the fat-soluble vitamins needs no justification considering the importance of this group of nutrients and the rate of expan sion of our knowledge of its role in cell biology, genetics, and disease. The level of our understanding has clearly moved from knowing what fat soluble vitamins do to how they perform their functions. Hand in hand with a knowledge of their molecular mechanisms of action is the recognition that vitamins are used sparingly, and regeneration processes operate in certain cases to recycle vitamins from their metabolites. We have divided the volume into alphabetical sections beginning with vitamin A and the carotenoids through vitamins D, E, F, and K, and ending with coenzyme Q. The contributors are all acknowledged experts in their particular fields and have made significant contributions to published research results. All have worked assiduously to deliver the product of their labors on a restricted time scale and to provide the most up-to date information on their respective topics. We are truly grateful for their indulgence.

The first demonstration of the existence of a vitamin and the full recognition of this fact are often attributed to the work of McCollum, who found that a sub stance in butterfat and cod-liver oil was necessary for growth and health of ani mals fed purified diets. It became obvious that an organic substance present in microconcentrations was vital to growth and reproduction of animals. Following the coining of the word vitamine by Funk, McCollum named this fat-soluble sub stance vitamin A. We can, therefore, state that vitamin A was certainly one of the first known vitamins, yet its function and the function of the other fat-soluble vitamins had remained largely unknown until recent years. However, there has been an explosion of investigation and new information in this field, which had remained quiescent for at least two or three decades. It is now obvious that the fat-soluble vitamins function quite differently from their water-soluble counter parts. We have learned that vitamin D functions by virtue of its being converted in the kidney to a hormone that functions to regulate calcium and phosphorus metabolism. This new endocrine system is in the process of being elucidated in detail, and in addition, the medical use of these hormonal forms of vitamin D in the treatment of a variety of metabolic bone diseases has excited the medical com munity.

Diet and Health examines the many complex issues concerning diet and its role in increasing or decreasing the risk of chronic disease. It proposes dietary recommendations for reducing the risk of the major diseases and causes of death today: atherosclerotic cardiovascular diseases (including heart attack and stroke), cancer, high blood pressure, obesity, osteoporosis, diabetes mellitus, liver disease, and dental caries.

To achieve and maintain optimal health, it is essential that the vitamins in foods are present in sufficient quantity and are in a form that the body can assimilate. Vitamins in Foods: Analysis, Bioavailability, and Stability presents the latest information about vitamins and their analysis, bioavailability, and stability in foods. The contents of the book is divided into two parts to facilitate accessibility and understanding. Part I, Properties of Vitamins, discusses the effects of food processing on vitamin retention, the physiology of vitamin absorption, and the physiochemical properties of individual vitamins. Factors affecting vitamin bioavailability are also discussed in detail. The second part, Analysis of Vitamins, describes the principles of analytical methods and provides detailed methods for depicting individual vitamins in foods. Analytical topics of particular interest include the identification of problems associated with quantitatively extracting vitamins from the food matrix; assay techniques, including immunoassays, protein binding, microbiological, and biosensor assays; the presentation of high-performance liquid chromatography (HPLC) methodology illustrated in tables accompanied by step-by-step details of sample preparation; the explanation of representative separations (chromatograms) taken from original research papers are reproduced together with ultraviolet and florescence spectra of vitamins; the appraisal of various analytical approaches that are currently employed. Comprehensive andcomplete, Vitamins in Foods: Analysis, Bioavailability, and Stability is a must have resource for those who need the latest information on analytical methodology and factors affecting vitamin bioavailability and retention in foods.

This book provides an authoritative and comprehensive source of information on the biochemical an metabolic aspects of digestion and absorption of different dietary fats and other lipids, with minimal discussion of the physical chemistry of the process, which has been covered in great detail in previous reviews. It is intended for both researchers and practitioners in the biomedical field who require detailed knowledge of the biomedical and metabolic transformations involed in the intestinal digestion and resynthesis of dietary fats and other lipids.

The subject for a volume on the fat-soluble vitamins needs no justification considering the importance of this group of nutrients and the rate of expan sion of our knowledge of its role in cell biology, genetics, and disease. The level of our understanding has clearly moved from knowing what fat soluble vitamins do to how they perform their functions. Hand in hand with a knowledge of their molecular mechanisms of action is the recognition that vitamins are used sparingly, and regeneration processes operate in certain cases to recycle vitamins from their metabolites. We have divided the volume into alphabetical sections beginning with vitamin A and the carotenoids through vitamins D, E, F, and K, and ending with coenzyme Q. The contributors are all acknowledged experts in their particular fields and have made significant contributions to published research results. All have worked assiduously to deliver the product of their labors on a restricted time scale and to provide the most up-to date information on their respective topics. We are truly grateful for their indulgence.

This book was stimulated by the enthusiasm shown by attendees at the meetings in Saxon River, VT, sponsored by the Federation ofAmerican Societies for Experimental Biology (FASEB), on the subject of the intestinal processing of lipids. When these meetings were first started in 1990, the original organizers, two of whom are editors ofthis volume (CMM and PT), had two major goals. The first was to bring together a diverse group ofinvestiga tors who had the common goal of gaining a better understanding of how the intestine ab sorbs lipids. The second was to stimulate the interest of younger individuals whom we wished to recruit into what we believed was an exciting and fruitful area ofresearch. Since that time, the field has opened up considerably with new questions being asked and new an swers obtained, suggesting that our original goals for the meetings were being met. In the same spirit, it occurred to us that there has not been a recentbook that draws to gethermuch ofthe informationavailableconcerninghow the intestineprocesses lipids. This book is intended to reach investigators with an interest in this area and their pre- and post doctoral students. The chapters are written by individuals who have a long-term interest in the areas about which they write, and many have been speakers at the subsequent FASEB conferences that have followed on the first.

The discovery of vitamins in the early 1900s, their later chemical characterization and the clarification of pivotal metabolic functions are sequential aspects of a brilliant chapter in the history of modern nutritional sciences and medicine. The name, derived from “vital-amines”, indicates their elementary metabolic key functions in human metabolism. Vitamins are truly families of compounds, which include precursors and various free and bound forms, all with individual roles in metabolism and function. A more recent approach therefore searches for the components, the understanding of their roles in physiology and pathology as well as looking for novel pharmacological applications. When used properly, vitamins are, indeed, “magical” substances. Due to their efficacy, they should therefore be regarded as drugs with effects and side effects to be weighted against each other. Today, it is not the previously fatal deficiency-associated diseases that are in the focus of interest, but rather the relation of suboptimal vitamin bioavailability to chronic disease. This is complicated by genetic susceptibility, lifestyle, and the presence or absence of health-compromising habits, such as smoking. In turn, the development and application of new and more sensitive and specific assays further enable us to look more closely into the many functions of vitamins. Water soluble vitamins are complex molecular structures and even today, many areas in vitamin biochemistry are not yet fully understood. Novel effects and functions of vitamins remain and continue to be discovered. This book presents most recent research results and fascinating new knowledge on the role and effects of the water soluble vitamins in man. Some of the most distinguished chemists, biochemists, biologists and clinicians have contributed valuable chapters sharing unexpected novel insights into the biochemistry, (epi)genetics, metabolism, and function of water soluble vitamins, with their potential for clinical applications. Thus, physicians, clinicians, scientists, researchers, epidemiologists. nutritional specialists and health professionals alike will find stimulating and fascinating new insight in the many roles that water soluble vitamins play in human health and disease.