Why You Need Vitmain D

When Johnny objects to a soap-and-water scrubbing, it is usually because he just doesn't like it. He would be on much sounder scientific, though dubious domestic, ground, if he simply told his mother: "Excessive bathing with soap removes from my skin the sterols which, if exposed to the ultra-violet irradiation of sunlight, would be converted into the Vitamin D I need for normal bone growth."

Not that Johnny would get very far, for bathing is a well-established social custom and quite indispensable for getting along with people. It is true, however, that oily substances in the skin are removed by soap scrubbings, and that these are the very materials which are changed into Vitamin D by the action of the sunlight. You can have a coat of tan that speaks of hours lying in the sun, yet the vitamin benefits of the sunshine may have been largely lost if you conscientiously bathed yourself before exposure. Too, the deeper your tan, the less sunshine vitamin you get, for the pigment shuts the vitamin-producing rays out from the skin.

For that matter, the benefit of sunbathing in city regions is probably overrated, from the vitamin point of view. Dust, smoke, and invisible urban effluvia may effectively curtain off the ultra-violet wavelengths of sunlight, which are the only ones that help your skin manufacture Vitamin D.

Practically, therefore, you will do well to get Vitamin D by other sources than suntan, although as an adult your needs for the vitamin are considerably less than the requirements of children. The particular virtue of Vitamin D is its masterly control over the distribution of calcium and phosphorus in the body—minerals which not only are the major building-blocks of bones and teeth, but which also play vital chemical roles in the body's functions.

Strangely enough, a relationship of Vitamin D to myopia (nearsightedness) has recently been demonstrated in animals. Lack of the vitamin and therefore of proper calcium and phosphorus metabolism has, in animals, weakened the outer coats of the eye and changed its refractive properties. The experimental animals were puppies, but a human application is not improbable.

It is babies, however, who are most seriously affected by Vitamin D shortages. They develop rickets, a disease in which deformed bones are exhibited as bowlegs, knock-knees, swollen joints, distorted pelvis, chest and spine. So important is this vitamin to infants that their diets always include cod liver oil or other concentrate, and the doctor's orders should be faithfully followed.

You can get a good deal of Vitamin D from ordinary foods, but the chances are you don't. Peanut butter, milk, graham crackers, cereals, and a vast number of other foods commonly used by children, are now available with Vitamin D artificially added. These are usually good investments. Oily fishes—tuna, salmon, herring, sardines—are the best sources among common unfortified foodstuffs. Eggs and butter also contribute small amounts.

The easiest way of securing Vitamin D is to use fortified milk, many varieties of which contribute a full day's vitamin quota per quart. Concentrates such as viosterol are potent and relatively inexpensive. Any surplus that you build up during exposure to summer sunshine is stored for doling out through the winter.