Fitness

Long ago it was learned that excessive amounts of vitamin D can be toxic. A toxic dose for adults appears to be 300,000 to 800,000 units per day provided this quantity is taken daily for several months: Toxicity causes vomiting, diarrhea, and sluggishness; calcium is withdrawn from the bones, the amount in the blood becomes excessively high, and much is lost in the urine. These symptoms are prevented if generous amounts of vitamin C are supplied. Fear of toxicity has caused the National Research Council to recommend only 400 units daily for persons of all ages.

Almost nothing is known of the amount of vitamin D which can be taken advantageously by an adult. Dr. Johnston 2 of the Henry Ford Hospital in Detroit studied the needs of adolescent girls, some of whom had ceased growing. He found that even though a generous amount of calcium was supplied by the diet, if no vitamin D was taken, more calcium was excreted than was eaten. When the vitamin was supplied, the amount of calcium absorbed into the blood paralleled the vitamin-D intake. For example, when 650 units of vitamin D were given daily for a time, and later 3,900 units were given, the quantity of calcium absorbed was increased tenfold. In some cases 1,950 units of vitamin D were given with more calcium than could be obtained from an average quart of milk (1,343 milligrams); still no calcium whatsoever was retained in the body; this amount of calcium was well absorbed when vitamin D was increased to 3,900 units daily.

Unfortunately, Dr. Johnston did not study the calcium absorption when still larger quantities of vitamin D were given. His studies indicate, however, that the adult can profit by taking at least 4,000 units of this vitamin daily. It is entirely possible that the ideal intake may be nearer 7,000 units per day; since this amount is certainly not toxic, it appears wise to err on the side of obtaining slightly too much rather than too little. Aside from the need during pregnancy and lactation, I suspect the. highest requirement is during the menopause; the calcium intake is usually lower then than during adolescence. Hot flashes, night sweats, leg cramps, irritability, nervousness, and mental depression, so frequently experienced at this time, can usually be overcome in a single day by giving calcium and vitamin D; when the calcium intake is already adequate, vitamin D alone can relieve these symptoms.

Vitamin D can be stored in the body provided an excess is obtained. For example, in England during World War II mothers were given cod-liver oil for their babies. Uncooperative babies sometimes burp up the oil, which stains clothing and smells bad; the oil is a nuisance for a busy, tired mother to give. Despite the fact that the oil was supplied free, severe bone abnormalities developed. English physicians, desperately trying to solve this problem, studied the effect of giving single massive doses of vitamin D by mouth to tiny infants in the doctors’ offices. Many similar studies were made later on the Continent and in America. It was found that a single dose of 300,000 units of the vitamin promoted good bone growth for a year, indicating efficient storage of the excess; this amount was never found to be toxic.

Since vitamin D is stored, the cheapest source I know of for adults is a capsule of 25,000 units each which can be taken once a week, as after breakfast on Sunday. When the requirements are unusually high, as during adolescence, pregnancy, and menopause, such a capsule might be taken to advantage every Wednesday and Sunday. These capsules, although available,” are so little used that druggists often tell customers they cannot be sold without a prescription. The Food and Drug Administration has asked that the 50,000 unit capsules of vitamin D be sold only on prescription but not the 25,000 unit capsule. Since vitamin D, like vitamin A, cannot be absorbed unless in the presence of fat and bile, this vitamin should be taken after a meal containing some fat.

The positive results gained by taking adequate vitamin D throughout adult life are identical with the advantages of having ample calcium, to be discussed in chapter 21. Since adults can absorb calcium without vitamin D, the taking of this vitamin is similar to buying fire insurance: you hope you will never need it, but if you do, it is wonderful to have.

An advantage is that vitamin D helps to prevent tooth decay. All decay is apparently caused by sugar being broken down by bacteria-produced enzymes into lactic and pyruvic acids; any acid can combine with calcium. If the saliva can reach the area where the acids are being formed, and if it contains ample amounts of dissolved calcium, these acids are neutralized by the salivary calcium, and no decay results. Dental erosion appears to be prevented in the same manner. Although the subject is still controversial, an increasing amount of evidence 4 indicates that both the enamel and dentin of mature teeth can be built up provided the nutrition is adequate; probably the two most important nutrients in such rebuilding are calcium and vitamin D.

Ample vitamin D undoubtedly plays an important role in the prevention of pyorrhea. If the diet is made adequate and all infection is removed, even severe pyorrhea can usually be arrested. Although pyorrhea is a disease involving infection and resulting from multiple nutritional deficiencies, the loss of teeth is caused by decalcification of the bones. When too little calcium is supplied the tissues, minerals are withdrawn from the jaw bones; the bones themselves become smaller and recede from around the teeth. As the bones recede, the gums likewise recede, exposing more of the tooth surface. The teeth appear longer than they should be, and the gums cannot fit tightly around the base of each tooth. Eventually, so little bone structure remains that it cannot hold the teeth firmly in place; the teeth, though they may be free from decay, become loose and must be removed.

Even when the teeth and all infection are removed, the destruction of jaw bones does not cease, nor does this destruction cease to be a problem. Dentures can fit well only when sufficient jaw bone remains on which to anchor them. If the nutrition is poor, so much bone tissue can be lost even six months or less after perfectly fitting dentures are made that the dentures shift, wobble, or refuse to stay in place. One of the delightful memories of my childhood is an occasion when a malnourished Methodist minister, apparently believing that the gospel was more effective when thundered, shouted his upper dentures into the congregation. An innocent dentist was probably blamed even by this good Christian; at least a dentist usually is. It is not a dentist’s fault that a person’s diet cannot maintain normal bone structure.

Often set after set of dentures have to be made as the destruction continues. Furthermore, persons whose bones are undergoing rapid destruction are so deficient in calcium that they are nervous wrecks; often they cannot stand to wear dentures no matter how well they fit. For a time a dentist referred to me many patients who complained that new dentures did not fit. As soon as the patients’ diet was made adequate and their nerves relaxed, there were no more complaints.