742 MAN'S PHYSICAL WKLFARE Dietary surveys which have been conducted by the Department of Agriculture . . . indicate very clearly that in the neighborhood of one-third of our entire population are receiving diets which, according to modern standards of nutrition, are definitely inadequate. Those diets are so poor that while they supply enough calories — and, of course, all of our population, speaking in general terms, get enough calories — they are deficient in minerals and vitamins to such an extent that we see wide-spread symptoms of them. All groups are affected — it is by no means confined to the low economic groups.' In 1922 Harry Steenbock discovered that milk and other foods when irradiated with ultraviolet light were increased in their vitamin-D content. He patented his irradiation process and turned down fabulous ofTers for his patents. These patents were turned over to the University of Wisconsin to create a research fund. Steenbock received ten dollars for the patent, while the Wisconsin Alumni Research Foundation had received over $1,400,000 in royalties by 1941. The foundation stipulates that only major food items shall be irradiated and that the companies manufacturing these foods may not increase the prices of these foods because of their irradiation. The foundation also checks all advertising claims dealing with irradiated foods. Over two billion pounds of evaporated milk, representing 60 per cent of the evaporated milk produced in the United States, are irradiated annually, while many people buy irradiated fresh milk. Research workers in the Universities of Illinois, Toronto, Cincinnati, and Purdue, following Harry Steenbock's example, have contributed patents to similar research foundations. The University of Purdue owns 145 patents, from which it has already received more than a million dollars. Undoubtedly Harry Steenbock receives more real satisfaction from the knowledge that his patents are enabling many research workers to extend the frontiers of human knowledge than the owner of a milliondollar yacht could ever receive from his investment. Plants Are Stimulated by Vitamin Treatments. Thiamin chloride has been widely publicized as a stimulant for root growth to be used especially when transplanting plants. The majority of plants probably make all the vitamins that they need, but there are some plants that resemble animals in their inability to manufacture one or more of the vitamins. One trillionth of a pound of vitamin Bi produces a measurable effect 1940. » W. H. Sebrell, Address to the Millers' National Federation, St. Louis, Mo.. Dec. 5.
VITAMINS, ENZYMES, AND HORMONES 743 in the growth of bread mold, while one trillionth of a grain of vitamin H (biotin) produces a measurable effect on another mold. There are at least a dozen vitamin-like substances that affect plants. The action of vitamins on plants seems to resemble their action on animals in that they serve as coenzymes. Coenzymes are substances which are essential to the action of enzymes; for example, vitamin Bi (thiamin) combines with phosphates to form an enzyme which catalyzes the breakdown of pyruvic acid, one of the products of the catabolism of carbohydrates. Enzymes Catalyze the Digestion of Foods by Living Organisms. Living organisms of all kinds, ranging from bacteria, yeasts, and molds to plants and animals, produce enzymes whose main function is to catalyze the splitting of such foods as carbohydrates, fats, and proteins into smaller molecules. This process is called digestion. Enzymes are not living organisms because they cannot reproduce themselves, but they do behave like living organisms in that they are inactivated by heat and various poisons. There Are Two Main Classes of Enzjrmes. Many enzymes catalyze the reaction of foods with oxygen; other enzymes specialize in the hydrolysis of proteins, fats, and carbohydrates. The oxidative enzymes frequently make a nuisance of themselves, oxidizing vitamins and causing the spoilage of foods in storage; the hydrolytic enzymes on the other hand are utilized considerably in industry for the production of amino acids and other substances produced by the hydrolysis of proteins and other types of organic compounds. In the quick-freezing of foods, it has been found necessary to blanch the foods, i.e., heat them for a short time in order to destroy the oxidative enzymes which would otherwise oxidize some of the vitamins in the foods even while they are kept below the freezing-point. Ascorbase is an enzyme that catalyzes the oxidation of ascorbic acid, while peroxidase catalyzes the oxidation of such fruits as peaches, bananas, and apples, causing them to turn brown in a short time after exposure to the atmosphere. Sulfur dioxide is used to inactivate these enzymes in the drying of fruits in order to keep them from darkening in color. Pineapple juice and grapefruit juice are also effective in inactivating these oxidative enzymes. The digestion of foods in the human body is accomplished by enzymes shown in the following table: