Good Health and Bad Medicine:
Diet - Part 2
Diet - Part 3
Diet - Part 4
Diet - Part 5
Some Common Food Fallacies
Teeth - Part 1
Teeth - Part 2
Teeth - Part 3
Obesity - Part 1
Obesity - Part 2
Read More Articles About: Good Health and Bad Medicine
Diet - Part 3
( Originally Published 1940 )
Among the most important discoveries in nutrition have been the substances known as vitamins. Vitamins are organic substances, not related chemically to one another, but having as a common characteristic the fact that they are indispensable to the growth and well-being of one or more animal species. Vitamins have been the subject of intense scientific investigation over the past twenty-five years. In the past few years thousands of scientific papers a year have been published about vitamins. And in the past few years thousands of advertisements have also appeared, exploiting discoveries in nutrition, not for improved health of the people but as a source of new profits for the food and drug manufacturers. The advertising of vitamins and vitamin products has been so intense and so conscienceless that practicing physicians as well as the untrained consumer have been stampeded into indiscriminate recommendation and purchase of vitamin products.
The following is a summary of what the consumer should know about vitamins:
Vitamin A is essential to growth, vision, and the maintenance in normal condition of certain specialized tissues of the body. That it is essential to growth was the first thing established about it. It was then discovered that a marked deficiency of the vitamin produces a disease of the eye known as "xerophthalmia," in which the outer lining of the eye becomes thickened and destroyed.
A moderate deficiency of the vitamin results in inability to see well in dim light, known technically as "nyctalopia," or night blindness.
Vitamin A is found in eggs, all dairy products (butter, cheese, whole milk, cream), and above all, in fish-liver oils. Green and yellow vegetables provide "pro-vitamin A," which is changed in the body to vitamin A during the process of digestion and assimilation. The deeper the green or yellow color of the vegetables, the more pro-vitamin A is present.
Frozen vegetables appear to retain their content of vitamin A, and cooking or heating destroys very little of the vitamin, so that no special precautions for retaining it need be observed in preparing foods for the table. Commercial canning is now done in such a manner that only slight destruction of vitamin A occurs.
It has not yet been established just how many Inter-national units of vitamin A are necessary for optimum health; authorities differ, and estimates range from 3,000 to 5,000 units. Most authorities consider 8,000-10,000 International units adequate for the growing child, especially if he also gets cod-liver oil.
It has been estimated that beyond the age of three, larger amounts of vitamin A are required, but it is unnecessary to resort to fish-liver oils or vitamin A concentrates provided the diet is well balanced—that is, if it includes at least one pint of milk, one or two eggs, about half an ounce of butter, and green or yellow vegetables daily.
The pregnant and nursing woman needs even more vitamin A, and it may be necessary for her to supplement the natural sources by a fish-liver oil or concentrate.
Mineral oil, used as a laxative, carries away from the body some of the vitamin A of vegetable origin (pro-vitamin A). If the diet is well balanced, however, if an average dose of oil (one ounce) is used and if it is taken at night before retiring, the loss of vitamin A will be negligible.
There has been much discussion of the relation of vitamin A to infections. Most of it is found in advertisements for cough syrups and cold remedies, where the vitamin goes under the name of the "anti-infective" vitamin (Smith Brothers' Cough Drops and Syrup, etc.). It is true that a person who is getting an inadequate supply of vitamin A is less capable of resisting infection than a normal person. The reason for this is that an adequate amount of vitamin A is necessary for the maintenance of a normal condition of the mucous membranes, which is important if bacteria are to be resisted. The way to improve the resistance, of course, is to have an adequate diet.
It is not true, however, that an amount of vitamin A in excess of that obtained by an adequately nourished person will further increase resistance to infection. As far as is known, an excess of vitamin A has no influence on the complex immunologic processes that are involved in infections. And the history of experiments in cold prevention bears this out. Taking an excess of vitamin A in the form of an artificial preparation will not prevent or reduce either the frequency or the severity of colds or the grippe; nor will cough drops containing vitamin A prevent or relieve coughs.
Vitamin B1 or Thiamin
Vitamin B1 was one of the first vitamins to be synthesized in the laboratory. It has been identified chemically as thiamin chloride, or thiamin. When all the vitamins have been chemically identified, the designation vitamin with the letters A, B, C, etc., will probably be discarded. Until then, however, it is useful to use both the vitamin designation and the chemical name.
Vitamin B1 is present in all living things. It is indispensable for the utilization of carbohydrates by the body. It also helps the appetite. Without an adequate supply of vitamin B1, the process of carbohydrate digestion and utilization is incomplete, and intermediate products that are harmful to the cells accumulate. The nerve cells may be affected, causing weakness. When the deficiency of B1 is severe, multiple neuritis or "beri-beri," a disease of the nerves, develops.
Vitamin B1 is not stored in the body to any extent, so that a constant supply is necessary. It is present in a wide variety of foods but not in considerable quantities in any one food. Therefore a varied diet is desirable. Bread and cereals are not good sources of vitamin B1 unless whole-grain products are used, since the vitamin is present in the germ portion and bran coats of the grain. Whole-grain cereals and breads can be advantageously included in the diet provided there is no intolerance to these foods. Many people, however, are allergic to whole-grain products or suffer from gastro-intestinal upsets when they eat them. The nutritional advantages of unmilled grain products must yield to considerations of comfort and freedom from undesirable reactions. Bran contains a considerable percentage of vitamin B1, but in some forms it is unfit for human consumption (see page 92).
Lean pork and liver are excellent sources of vitamin
B1. Egg yolk, lean beef, oysters, kidney, heart and chicken are also good sources. Almost all fruits and vegetables contain some vitamin B1. Peas, beans, soy-bean, barley, brown rice and corn contain more than the others. Although milk does not contain as much of this vitamin as the foods just mentioned, the daily use of an abundance of whole, skim milk or buttermilk to drink or for cooking makes it a fairly good source for most children and adults,
It is well to keep in mind that while thiamin is present in a wide variety of foods, there are few foods of plant or of animal origin that are potent sources of the vitamin. In planning adequate diets, therefore, it is necessary to depend on several food items to furnish the day's supply of thiamin.
Methods of cooking have an important bearing on the vitamin B1 content of foods. The vitamin is readily soluble in water and may be easily washed out in cooking when much water is used. Therefore the water in which vegetables and fruits are cooked should not be discarded but should be used for gravies, soups and syrups. There is also less loss when little water is used. The presence of an alkaline sub-stance like sodium bicarbonate greatly increases the amount destroyed. That is one reason why cooking green vegetables with soda to preserve the green color is a very bad practice.
Two eggs instead of one for breakfast and another glass of milk would provide an additional 45 units. This diet would also provide for adequate minerals and all other vitamins required by the average adult.
Vitamin BI is destroyed by long continued heating, but undergoes little destruction when heated at the boiling point of water for as long as an hour. In general, the destrucdon of the vitamin is less when the food is heated at a high temperature for short periods than when heated at low temperatures for long periods. Thus foods kept on a hot stove for many hours, as in cafeterias and restaurants, probably lose much of their B1 content. Steaming is the best method of cooking vegetables, since the time required is short and the amount of water used is small. The juices drawn out in cooking should never be discarded. Vegetables and fruits suffer some loss of vitamin BI during canning. The amount lost varies with different brands. Whenever possible, the fresh vegetables and fruits should be used.
Some nutrition workers believe that the average intake of vitamin BI is nearer the minimum or sub-minimum than the optimum requirement. It is probably true that the average American diet is lacking in adequate amounts of vitamin Bi. But there is a difference between an average diet and an adequate diet. It is possible to meet the optimum requirements for vitamin BI (and other vitamins as well) by the abundant use of such familiar staples as eggs, fruits, vegetables and unmilled cereal products.
For the average normal person a daily intake of a variety of such foods will contribute to making the diet adequate, and make it unnecessary to use thiamin or BI preparations or foods reinforced with synthetic thiamin.
Vitamin B2, G or Riboflavin
This vitamin, designated by two different letters and a chemical name, is present in the same foods that are rich in vitamin B1. This vitamin appears to be necessary for the prevention and cure of certain symptoms frequently associated with pellagra. There is no evidence at present of a widespread deficiency of this vitamin. Among the malnourished many instances of a deficiency of this vitamin are being recognized.
P-P Factor or Nicotinic Acid
This vitamin is necessary for the prevention of pellagra. This disease is not rare in America. About a quarter-million people in the Southern States are afflicted with the disease and at least 4,000 die every year from it. It is a gruesome disease which mutilates the skin, devours the bowels and eventually leads to insanity. It has been conclusively proven that pellagra is caused by a deficient diet, for it can be produced at will in man and experimental animals by diets deficient mainly in nicotinic acid. Both experimental and spontaneous cases of pellagra can be relieved to a great ex-tent by 'administration of nicotinic acid. Complete cure requires an adequate diet. Consequently, the problem of pellagra will be solved not when every indigent gets a supply of nicotinic acid, but only when he is able to obtain a full, adequate diet.
The prevalence of a dietary deficiency among so many Americans has been conclusively shown to be due to social and economic conditions. Wage levels and relief income in the South are the lowest in the country, so that many people ate forced to subsist on a diet of molasses, corn bread and salt pork—a diet almost totally deficient in the pellagra preventing vitamin. In some instances, also, the dietary deficiency can be attributed to ignorance about proper dietary habits, to food idiosyncrasies, or to gastro-intestinal disorders.
Very little information in regard to the exact nicotinic acid content of foods is available. It is known that dry brewer's yeast, 'meats, especially liver and glandular organs, are good sources of the vitamin. It is also known that a varied diet which includes meat, milk, eggs, fruits and vegetables in adequate amounts prevents pellagra, so that these foods are probably good sources. Nicotinic acid is very heat stable and not destroyed by cooking. It is, however, soluble in water and may be lost to a considerable extent if the water in which food is cooked is discarded.
Vitamin C or Ascorbic Acid
A deficiency of vitamin C in the diet causes the disease known as scurvy. From days of antiquity, lack of vitamin C in the dietary had caused mankind much suffering, and it was not until the eighteenth century that the first clear account of the disease was given and the efficiency of fruit juice in preventing and curing the disease was established.
The function of vitamin C has been well summarized by Dr. L. J. Harris as follows: "As is well known, the animal body is often compared with a furnace. Material derived from the food is continually being burned all over the body, in the millions of minute cells of which the body is composed. This gives the necessary heat and energy for the multifarious work of the living being as a whole. It is in this process of respiration, or oxidation, that vitamin C plays a role, i.e., in the balanced chemistry of oxidation-reduction. In the absence of vitamin C certain cells are no longer able to perform their function properly, and that is why in scurvy the blood vessels become too weak and bleeding results, and why the teeth, also, for example, lose their normal structure and become diseased."
The weakening of the blood vessels, especially the capillaries, is responsible for the characteristic symptom of scurvy a tendency for bleeding to occur in different parts of the body. X-ray examination also reveals certain specific changes in the bones.
Scurvy now occurs chiefly in infants who are fed on boiled milk and do not receive fresh orange juice. Active scurvy is uncommon in this country but recent medical reports show that many adults and children do not take as much fresh fruit and vegetables as they should and that many borderline cases are appearing with such symptoms as sore gums, loose and decayed teeth and "rheumatism." Drs. Dunlap and Scarborough of England believe that a deficiency of vitamin C in the diet may be a factor in producing anemia in working-class populations even in the absence of gross symptoms of scurvy.
It is essential for everyone to get an adequate supply of vitamin C every day, since very little is stored and none is manufactured by the tissues. Since there is little or no vita-min C in cow's milk prepared for the bottle, the bottle-fed infant should get about one ounce of orange juice daily. The normal breast-fed infant receives about 800 units from breast milk, provided, of course, that the mother is getting adequate amounts of vitamin C daily. During pregnancy and lactation it is estimated that 2,000-3,000 units daily will meet the requirements of the mother and the infant. An average of about 2,500 units is obtained from a tumbler of fresh orange juice. The school child also requires about 2,000-3,000 units. An adult requires about i,000 units—which can be gotten from about one-third tumbler of orange juice.
While orange juice is the most popular source of vitamin C, there are other citrus fruits abundant in this vitamin, including lemons, grapefruit and tangerines. Tomatoes and tomato juice are other major sources of it. About one tumblerful of tomato juice will furnish an adequate amount (i,000-2,000 units) of vitamin C to an adult. Most berries and all types of green and leafy vegetables are also good sources of vitamin C.
The vitamin C content of foods depends upon freshness, maturity and methods of preparation, handling and storage. The vitamin is very unstable and appears to be destroyed by heat, especially in the presence of oxygen or soda. An attempt is made, in the commercial canning process, to keep the destruction fairly low by performing the operations in a closed system in which air and oxygen are excluded by means of steam or high vacuum. That this is not always successful is indicated by a communication to the author from the Bureau of Home Economics of the U. S. Department of Agriculture, which states: "The chief loss in nutritive value during the canning of fruit juices is the reduction of vitamin C content. This loss varies from product to product, depending upon the method used. Canned grapefruit juice probably contains 8o% to 95% of the original vitamin C. Certain brands of tomato juice may contain almost as much vita-min C as the fresh tomatoes. On the other hand, certain other brands may be almost useless as sources of this factor.
"Vegetables suffer considerable loss of vitamins and some loss of mineral material during canning."
In view of such findings, fresh fruits should be used when-ever possible. Canned juices are usually cheaper, however, and when cost is a factor they may be consumed with reasonable assurance of obtaining an adequate amount of vitamin C.
Avoid bottled orange juices or juices sold at counters from large containers. These usually have little or no vita, min C because of dilution and quick deterioration of the vitamin during handling and storage. Tomatoes, however, are an excellent source of vitamin C in every form—juices, whole or as soup, and even when they have been cooked. This is due to the fact that they are rich in vitamin C to begin with, and because the natural acidity preserves the vitamin during cooking and canning.
Baking white potatoes in the skin preserves the vitamin. The large amount of potatoes eaten by those on a poverty or relief diet makes their contribution of vitamin C significant.
Vitamin C, like vitamin B1, is soluble in water, so that all vegetable and fruit juices drawn out in cooking should be served in one way or another.
Vitamin D has been the subject of intensive investigation for many years. Perhaps a chief reason for this is that a deficiency of this vitamin produces in infants a dramatic and very common disorder of bone development—rickets. In this disease, calcium, which is obtained by the infant from mother's or cow's milk, fails to deposit in the growing ends of the long bones and in the flat bones of the head. Consequently the entire skeleton of the body remains soft and the bones yield to pressure upon them caused by standing, sitting, walking, lying down or even breathing. Children with rickets show deformities of the head, chest, and extremities—bow-legs are one of the most obvious and common manifestations.
Although it had long been known that rickets are more common in winter than in other seasons, and are nearly absent in summer, it was not until i 919 that an explanation was found. In that year, it was shown that the disease is absent in summer simply because babies are then exposed to the sun, the ultra-violet rays of which prevent and cure rickets. Thus, rickets are rare in regions such as the tropics where sunshine is plentiful, and are common in many northern countries where there is a lack of adequate sun-shine.
At the same time it was noted that the Eskimos, who have long winters and very brief periods of sunshine, do not get rickets because their diets include fish oils—rich in vitamin D. Exposure to sunlight or the taking of fish oils were thus demonstrated to have the common effect of preventing or curing rickets. Ultra-violet light was effective because it manufactured vitamin D in the skin of those exposed to the rays; cod-liver oil was effective because it was itself rich in vitamin D.
Later it was shown that vitamin D was necessary so that the body could utilize the calcium and phosphorus obtained from food; that babies who do not get enough sunshine or vitamin D will suffer not only from rickets but also from spasmophilia or infantile tetany—a disorder of calcium and phosphorous metabolism.
It is known that sunlight or vitamin D is essential to the proper growth and development of children, but its importance in adult life is not yet established. The only disorder of adults which has so far been attributed to a vitamin D deficiency is a rare disease known as osteomalacia.
The distribution of vitamin D in natural food substances is rather limited. It is practically absent from fruits and vegetables. The amount of vitamin D in mothers' or cow's milk is variable and depends to a large extent on the amount of vitamin D in the food eaten. The vitamin D content of cow's milk is small and variable. It is greater in the summer when the animal is exposed to the sunshine. Egg yolk, while it does contain some vitamin D, cannot be considered an adequate source of it for children in winter months. The vitamin D content of egg yolk also depends on the diet and the amount of sunlight the chicken receives.
The most abundant natural source of vitamin D is the oil of many species of fish. And the oil used most extensively for its anti-rachitic (anti-rickets) properties is obtained from the liver of the cod. Potent oils have also been produced from the livers and bodies of certain other species of fish—halibut, puffer fish, goosefish, shark, haddock, herring, sardine, salmon, burbot, and a class of fish known as the percomorphi. The oil from some of these fish is inferior in vitamin D potency to cod-liver oil, while the oil of others (percomorphi, for example) is almost a hundred times as potent. All these oils contain vitamin A in addition to vitamin D.
The cod-liver oil sold in the United States is either imported from Norway or obtained from the livers of cod caught along the coast of Newfoundland and Nova Scotia. A few brands of Norwegian cod-liver oil are inferior in vitamin D content to Newfoundland oils. This is not be-cause of any inferiority in Norwegian fish, but because of the dishonest practice of some distributors, who dilute the oil and then sell it at a low price. The oil that is sold in the drug or department stores under the druggist's or department store's own label should be bought with caution be-cause there is usually no assurance as to its potency.
The requirement of the U. S. Pharmacopoeia for average cod-liver oil is that it contain not less than 85 international units of vitamin D and 600 units of vitamin A per gram. Most cod-liver oils contain two or three times that amount of vitamin D. Two teaspoonfuls of cod-liver oil per day, as prescribed by a physician, will usually provide all the vita-min D required by an infant or child.
Because it becomes rancid and loses some potency when exposed to air, cod-liver oil should be bought in the original unbroken package and in small quantities, preferably in dark-colored bottles of four, eight, or sixteen ounces. The neck of the bottle should be wiped off and the bottle tightly corked after each use. It should be kept in a dark, cool place, preferably in a refrigerator.
The disagreeable taste of cod-liver oil and the relatively large dosages required are largely responsible for the wide use of other oils higher in vitamin potency which can, therefore, be given in smaller amounts. Such an oil—and one of the first to be introduced—is the oil obtained from the liver of the halibut. It contains not less than 540 units of vitamin D and 50,000 international units of vitamin A per gram. This compares with 85 to 26o units of vitamin D and 85o to 2,000 units of vitamin A for pure cod-liver oil. Ten to twenty drops a day as prescribed by a physician will provide adequate amounts of vitamin D and more than an adequate amount of vitamin A.
But halibut-liver oil is an expensive source of vitamin D, since its vitamin D content is relatively small compared with its high vitamin A potency. And it should not generally be used alone unless the physician wishes the administration of Iarge doses of vitamin A. Halibut-liver oil (haliver oil) is now fortified with viosterol, increasing the vitamin D potency to not less than 10,000 unit' per gram. It is more satisfactory for general use in this form. Because of the high vitamin potency, it is also prescribed in drop dosage.
Other fish-liver oils sometimes used as sources of vitamins A and D include those of the hake, the burbot, and the percomorphi (Oleum Percomorphum). Many of the fish-liver oils are used in the preparation of concentrates (drops, capsules and tablets), some of which contain only vitamins A and D, while others are combined with other vitamins or with calcium salts. The potencies of such preparations vary considerably, depending upon the source and the method of producing the concentrates. The net result of the variability, unfortunately, is confusion on the part of both the public and the physicians.
Viosterol in oil is an oily solution of irradiated ergosterol (an oil derived from plant material or yeast) containing approximately 10,000 international units of vitamin D per gram. It contains no vitamin A.
Because of its high vitamin D potency, only a few drops of viosterol a day are generally prescribed, and it is therefore important to see that the entire amount is taken. It should not be added to the milk formula or to orange juice, since the oil will simply float and cling to the sides of the container; the infant will receive little or none of the vitamin D.
Food manufacturers have eagerly seized upon discoveries in vitamin research, and they advertise breads, cereals, candies, chewing gum, ice cream and beer containing vita-min D. Some of these foods acquire vitamin D through irradiation with carbon or mercury-quartz lamps, others through the addition of viosterol or concentrates of fish-liver oils. Quite aside from the fact that the requirements of normal adults for vitamin D is not known, and that a large amount is manufactured in the skin by seasonal exposure to sunlight, the number of units in such food and drink concoctions is so variable that they must never be depended upon as a source of vitamin D. The cheapest and most reliable sources of the vitamin are sunlight, fish oils and concentrates and viosterol.
Cosmetic manufacturers have joined food makers in the vitamin stampede. Irradiated facial creams and sunshine soaps are found on drug counters throughout the country. Although a very small amount of vitamin D can be absorbed from a cosmetic preparation through the unbroken skin, there is no evidence that it can have any beneficial effect on the skin itself. And the amounts which would have to be present in cosmetics for any appreciable absorption are hundreds of times the amounts usually found in the cosmetic.
The Council of Pharmacy and Chemistry of the American Medical Association has recently deplored the indiscriminate fortification of foods with vitamins and minerals. One exception is the fortification of milk with vitamin D. Vita-min D milk offers an excellent vehicle for vitamin D for infants—who need it most.
There are three types of milk fortified with vitamin D:
1. Irradiated milk, which is produced by treatment of the milk with ultra-violet light;
2. "Vitex" milk, which derives its potency from the emulsification of the milk with viosterol or with a fish-liver oil concentrate;
3. "Metabolized" or "yeast" milk, which is made antirachitic by feeding the cows irradiated yeast.
Only about 135 international units of vitamin D can be added to a quart of milk by the irradiation process, and this is below the amount necessary for complete protection against rickets. But the last two types do offer reliable protection. They contain approximately 400 units of vitamin D in a quart, but the quantity is so well dispersed and so completely absorbed by the body that it appears adequate for complete protection, even though it is only about one-third of the amount usually prescribed for infants when the vitamin is administered in other forms. "`Vitex" or "metabolized" milk is the ideal food for the prevention of rickets and the administration of vitamin D. It is unfortunate that its cost (about 18c a quart) puts it beyond the reach of the millions of infants and children who need it. There is no reason why milk producers cannot produce a cheap vita-min D milk for consumers. A Grade B pasteurized milk is just as healthful a vehicle as the Grade A or certified milk in which the vitamin is now incorporated. Irradiated evaporated milk, like irradiated fresh milk is not an adequate source of vitamin D. Some fortified evaporated milk is avail-able, however, and when this is diluted with an equal amount of water, it offers a satisfactory substitute for Vitex milk, at a much lower cost.
The prescription of the correct dosage of vitamin D should be left to the physician. It is unfortunate, however, that many physicians derive their knowledge of the dosage of vitamin D from a label on a bottle or from manufacturers' literature.
The following dosages of vitamin D preparations are for the prevention and not the cure of rickets. The latter is a problem for a competent physician:
For the prevention of rickets in full-term babies, about 1,200 international units of vitamin D in oil (daily) are sufficient. The necessary supplement of vitamin D is de-pendent upon the available sunshine. In localities where the winter is long or where the air contains much dust, as in industrial cities, 1,200 units may be a definite minimum. There are individual instances where more may be required, as in digestive disturbances, where the vitamin D is not completely absorbed. Negro children, because of their greater susceptibility to rickets, require larger doses than do white children. But in many instances smaller doses will be sufficient. In fact, there is some evidence that growth of bones is better with smaller than with larger doses.
Each infant requires individual care, and a physician or pediatrician may increase or diminish the daily dose of vita-min D, depending upon the child's development and environment.
Two teaspoonfuls of a good cod-liver oil (see page 171) will furnish at least i,000 units of vitamin D. Children who show distaste for the oil should not be forced to take their vitamin D in this form. Many instances of lipoid pneumonia have been traced to forced feeding with cod-liver oil.
Halibut-liver oil with viosterol, and viosterol in oil, are easier to administer, since the amount required is much smaller. About 10 drops of either daily is adequate for most children. Again it must be emphasized that the oil should not be added to the milk formula or to the orange juice in a glass. It should be dropped into a teaspoon containing a little orange juice so that none of it will be lost.
Capsules and tablets of vitamin D concentrate should be used by older children and adults only when there is a definite indication for a supplement of vitamin D.
Artificial sunlight from a mercury-quartz or carbon-arc lamp will prevent and cure rickets, but the dosage and manner of administration require high technical skill and must be reserved for use in a hospital or under a physician's direct supervision. Unregulated exposure to a lamp can cause serious and even fatal reactions in infants.
Preparations of vitamin D containing malt need not be used, particularly since they may cause digestive disturbances.
The chief reason for the use of vitamin D preparations is the prevention and cure of rickets. But rickets is a disease of infancy and early childhood; it occurs but rarely after the second year of life.
Many physicians, however, recommend that children up to the age of about twelve should receive a daily dose of a vitamin D preparation during the winter months when they are not exposed to sunshine. In regions where there is bright sunshine all year round, exposure to sunlight will provide all the vitamin D that is necessary.
While the exact requirements of adults for vitamin D is not known, some physicians recommend that persons who are not exposed to sunlight during the summer months, such as miners or those confined indoors, should get a moderate dose of vitamin D daily, particularly since even the best diet contains very little vitamin D. It is likely that not more than 20o units of the vitamin daily are necessary.
In pregnancy, a daily intake of about 800 units will help to safeguard both the mother and child.
Taking cod-liver oil or other vitamin D preparations will not, as is popularly supposed, prevent or cure colds or other infections.
The use of very large doses of viosterol or vitamin D concentrates for the treatment of arthritis and psoriasis has been recently reported in medical journals and newspapers, but there is as yet no definite evidence that any genuine relief or cure has been obtained. On the other hand, it can be said that serious danger does attend the use of the very large amounts of vitamin D recommended--100,000 to 500,-000 units daily.
Such large quantities of vitamin D may increase the concentration of calcium in the blood to abnormally high levels or produce deposits of lime salts in soft tissues, especially the blood vessels and the kidneys. If it is desired to risk this treatment in spite of such dangers, it is essential to be under the care of a competent physician who can determine the level of calcium in the blood at frequent intervals and watch for symptoms of overdosage.
The alleged toxicity of cod-liver oil has agitated many people. It can be definitely stated, however, that cod-liver oil or vitamin D concentrates in ordinary doses will not cause heart disease, kidney disease, or any other disease.
Cod-liver oil, viosterol or vitamin D concentrates may produce toxic effects in experimental animals, when they are subsisting on limited diets or when large quantities are given. But with humans, the daily experience of thousands of physicians indicates that, in normal doses, cod-liver oil, viosterol, and concentrates will not cause harm. Half a mil-lion units of vitamin D administered daily to a human being may damage the heart, blood vessels and kidneys. But such toxic doses are far from the normal therapeutic and prophylactic doses used in the treatment and prevention of rickets.
Very little is known about this vitamin, except that it appears to be essential for fertility in animals and perhaps humans. Vitamin E is widely distributed in nature and some is found in almost every food. The richest source of the vitamin is wheat germ, but green vegetables are also excellent sources. Apparently very little of the vitamin is needed for normal function and no deficiency need be feared if an adequate diet is obtained.
"Vitamin F" is not a vitamin at all. The term is used mainly by cosmetic manufacturers in connection with cosmetic products containing linseed oil or fatty acids such as linoleic acid. The use of the term "vitamin F" for these sub-stances is not warranted, according to responsible authorities. There is no evidence that the use of products claiming the presence of "vitamin F" will fulfill any of the claims made for this so-called vitamin.
This is one of the most recently discovered vitamins. Although its function is not yet clearly known, it appears to be concerned with the process of blood clotting and coagulation. It is used in the treatment of certain bleeding disorders. Vitamin K is present in large amounts in alfalfa, spinach and kale in moderate quantities and in other green vegetables and in liver.
There are several other vitamins and vitamin factors, but very little is known about them.