Columbia Ency Nutrit

Although the writing is somewhat dry, this useful sourcebook from the Institute of Human Nutrition of the Columbia University College of Physicians and Surgeons provides an authoritative compendium of information relating to a wide variety of topics. Short articles, alphabetically arranged, proffer concise and up-to-date discussions of such subjects as food additives, vegetarianism, vitamin deficiencies, food processing, sources of iron, macrobiotic diets and nutrient requirements during pregnancy. Not all the articles are about nutrition, however, and there are lucid writings on related topics like stress and exercise. Welcome dietary recommendations are given without pep talks or filler, and the evenhanded work doesn't take a dogmatic approach to controversial issues. In its entry on vitamin C, for example, the book states that ""there are no definitive answers about consuming large doses,'' citing one study demonstrating that the vitamin supplement reduces the severity of the common cold and another study that was unable to prove any differences between those taking and those abstaining from the supplement. (March)