Of the conditions which are due to a lack of vitamins in the food, the commonest in temperate climates are rickets and scurvy. As these are respectively due to lack of Vitamins D and C, it is an indication that these are the vitamins which are most likely to be lacking in the average dietary.
Especially is this true in childhood, when lack of Vitamins C and D do most of their harm, and for that reason especial care must be used to see that in the infant’s and child’s diet they are deliberately introduced in the form of cod liver oil, or viosterol, or irradiated milk for Vitamin D, and of orange or tomato juice in the case of Vitamin C.
The disease which is due to lack of Vitamin B in the diet is seldom encountered in tropical and oriental countries. This is called “beri-beri,” and usually appears in the form of a paralysis due to neuritis. Very rarely do we see a case in temperate climates which might be called beri-beri, and in all of these cases the patient has been living on a very peculiar diet, which indicates that it is pretty hard to exclude Vitamin B from the dietary.
Even rarer is the one disease which is ascribed to lack of Vitamin A. It is called “xerophthalmia,” and consists in an inflammation of the eye, usually in infants. Vitamin A also is said to be the anti-infective vitamin or, in other words, its presence in the food tends to raise our resistance to various infections, even including colds.
Along these lines much has been claimed for the introduction of carotene, the yellow pigment which is found in carrots, corn and other vegetables, and which is supposed to be the chemical from which Vitamin A is formed. Vitamin A itself is colorless.
However, most nutritional experts believe that it is unnecessary to take any pains to add Vitamin A to the diet, as the average diet will contain sufficient of it. It is probable that the vitamins all influence a number of functions of the body, and lack of them produces some vague condition, such as fatigue, susceptibility to cold, sleeplessness or sleepiness, lack of regular growth, etc.
There are also probably many vitamins that we do not know about which most of us take into our bodies because we eat a general diet. The lesson of what we do know about the vitamins is to arrange a well-balanced diet, including all the elements that the average person eatsfruits, vegetables, meats, milk, eggs, bread, butter, saltand to reject strange faddy and unusual advice on the subject of food.