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119 Morgan Hall
University of California
Berkeley, CA 94720-3104
E-mail: retinol{at}nature.berkeley.edu
A seminar course on vitamins that I have been teaching for many years has suffered from a continually decreasing number of students, perhaps because vitamins are no longer scientifically fashionable. This attitude is shortsighted on the part of the students. Any drugstore today has shelves groaning under the load of bottles of vitamins. After graduating as nutrition professionals, students will be expected to be particularly knowledgeable about vitamins. Therefore, a textbook on nutrition focusing on vitamins, deeply embedded in biochemistry, is very welcome.
The second edition of David A Bender's Nutritional Biochemistry of the Vitamins is a greatly expanded version of the 1992 edition. Although the emphasis, as in the first edition, is on metabolism, the author presents a comprehensive treatise that spans the metabolic biochemistry, clinical nutrition, epidemiology, and pharmacology of vitamins as well as their toxicity and their relation to cancer.
The separate chapters on each vitamin are subdivided into sections: nomenclature, vitamers and units of activity, absorption and metabolism, catabolism and excretion, metabolic function, deficiency and deficiency diseases, assessment of nutritional status with reference to the particular vitamin, requirements and reference intakes, toxicity, and pharmacologic uses. Each chapter ends with an up-to-date list of references, which includes key reviews or books for further reading. An extensive list (almost 1000) of the references cited in the text can be found at the end of the book, with references dated up to 2002.
Each chapter begins with a brief overview of the discovery of the vitamin. The section on nomenclature and vitamers includes a discussion of each vitamin's biosynthesis in plants and bacteria, a topic rarely found in texts on vitamins, and includes up-to-date references. The biosynthesis of nicotinamide nucleotides from tryptophan is particularly extensively treated. The section on the metabolism of vitamins reviews their digestion, absorption, and metabolism.
The heart of each chapter is the function of the vitamin in metabolism, with discussions that go into great depth on the biochemistry of the metabolic pathways in which the vitamin participates. Of particular note is the beautifully organized section on the complex metabolic functions of vitamin C, which is divided into the copper-containing hydroxylases and the 2-oxoglutarate–linked iron-containing hydroxylases. Throughout the book, the pathways are illustrated by superbly drawn structural formulas of exceptional clarity. Especially impressive is the diagram of the visual cycle, which clearly delineates the isomerization of vitamin A by beautifully presented chemical structures.
Deficiency signs and symptoms are described with accompanying details of the biochemistry underlying the phenomena. Sections on the assessment of nutritional status with respect to the particular vitamin are accompanied by tables listing blood and urine concentrations under normal and deficient conditions. Such a table is particularly valuable for the biochemical indexes of vitamin A status and gives both µmol/kg and mg/kg for liver vitamin A esters. The table also includes values in µmol/L and µg/L of retinol, total carotenoids, retinoic acid, and retinol-binding protein in plasma of healthy and vitamin A–deficient human subjects. Finally, tables are given of reference intakes and requirements.
An unusual chapter is devoted to bioavailability, requirements, and reference intakes comprising all vitamins, with tables showing, for instance, the various recommended intakes in different countries and a table titled "Toxicity of Vitamins. Upper Limits of Habitual Consumption and Tolerable Upper Limits of Intake."
Practical details are discussed, such as the difficulty in interpreting thiamine requirements, because often authors do not specify whether they describe the free base or the hydrochloride. Myths are dispelled, such as the supposed requirement of ascorbate in the hydroxylation of tyrosine.
The book ends with a chapter on marginal vitamins, including carnitine, choline (with a discussion of the possible essentiality of choline), inositol, taurine, ubiquinone, and phytonutrients. This chapter includes structural formulas and information on the marginal vitamins' metabolism and possible function as vitamins.
A surprising omission in a book on vitamins is their sources in food. One would expect at least a table for each vitamin listing concentrations in the principal foodstuffs. Perhaps a future edition will stress the low amount of vitamin D in human milk, correct the structural formula for vitamin D2, and omit the reference to the erroneous mannose-carrier function of vitamin A.
I highly recommend this book as a textbook for advanced students in nutrition, provided they have a solid background in biochemistry. It would also serve as an excellent reference source by virtue of its many tables on indexes of nutritional status or reference intakes for particular vitamins.