Vitamin A

By Florence W. Sperry, B.S., M.S.

   At the present time the vitamins in food are being discussed to a great extent. New work and new discoveries are being made known at a rapid rate. Considering that vitamins are relatively young in the scientific world (some 30 years since the first was discovered) and have been coming so rapidly to the front, the more knowledge we have of them the better we can combat their deficiencies. Vitamins A, B, C, and D are definitely known to be essential for human beings. Vitamin E, which is always listed and discussed, is essential to rats. Vitamin G is also needed by animals and probably will be shown to be essential in the human diet.

Vitamins A, D, and E are soluble in fats and are associated with lipid extracts of natural products. Vitamin A, as such, does not occur in the plant world but carotene, its precursor, is rather widely distributed. Vitamin A however has been obtained from fish oils. Its chemical nature was discovered through a knowledge of the structure of carotene, a pigment found in green and yellow plants. This occurs as a, B, y-carotene. All of these may be converted into Vitamin A in the liver, B-carotene has twice the vitamin value of the other two forms as theoretically one molecule of B-carotene should give rise to two molecules of Vitamin A, while the other carotenes yield only one molecule. Vitamin A was discovered simultaneously in 1913 by McCollum and Davis, and by Osborne and Mendel.

Vitamin A deficiency results in a change in the epithelial cells in glands and their ducts and in many organs. Xerophthalmia, an eye disease, results in severe Vitamin A deficiency. Particular interest is now centered on night blindness, an impairment of vision due to failure of the visual purple of the retina to be regenerated after it has been bleached by light. In the absence of adequate amounts of Vitamins A, this regeneration is retarded. Deficient Vitamin A stunts growth and development, results in increased incidence of respiratory, skin, ear, and sinus infections; inflammations and infections of the alimentary tract; cysts; and urinary calculi. An excess of Vitamin A is stored in the tissues, lungs, kidneys, and liver of the body.

Vitamin A potency is measured in Units, International and Sherman, sometimes designated as U.S.P. and A.C.S. Units respectively. Attempts have been made to determine conversion factors for changing one Unit to another, but since practically all the older Units have been defined in terms of animal behavior, there is no absolute value. However the method most used is to multiply the Sherman Unit by the factor 1.4 to convert it to International Units. The Sherman or older Unit is most often used for Vitamin A, therefore the Vitamin A requirement will be expressed in Sherman Units.

Rose gives the following daily requirements for different ages.

Infant …………………………………….. 2,300 S. U.
One Year ……………………………….. 3,000 S. U.
Nursery School………………………….. 6,000 – 7,000 S. U.
High School ……………………………… 5,600-10,000 S. U.
Adult ……………………………………… 3,000 S. U.

The above Vitamin A daily requirement can be obtained in the diet by the use of green and yellow pigmented foods. Note that it is true, observe foods listed in Table. Since carotene is converted to Vitamin A in the liver one would expect high Vitamin A potency in the liver of animals and fish. Note that calves liver and cod liver oil have high values.

 

Units per 100 grams of foods riches in Vitamin A (750 grams and over.)

Units
Apricot …………………………………………………………………. 5,400
Apricot, dried, commercial ………………………………………………. 7,000
Beans, green snap …………………………………………………… 1,000
Brocolli, flower …………………………………………………………. 7,000
Brocolli, leaf …………………………………………………………… 30,000
Brocolli, stem ……………………………………………………………. 1,500
Butter, average …………………………………………………………. 2,200
Carrot, young ……………………………………………………………. 3,000
Carrot, mature ………………………………………………………….. 5,500
Celery, green …………………………………………………………….. 1,500
Chard ………………………………………………………………………. 17,200
Cheese, Cheddar ………………………………………………………. 2,500
Cheese, cream …………………………………………………………… 3,500
Cheese, Parmesian …………………………………………………… 1,250

Cod liver oil. Use value given on package also see Vitamin products July issue Nutrition and  Dental Health.

Collard ……………………………………………………………………….. 4,500
Cream, 20% ………………………………………………………………….. 750
Dandelion …………………………………………………………………. 25,000
Eggs, whole …………………………………………………………………. 1,000
Eggs, yolk …………………………………………………………………….. 3,000
Kale …………………………………………………………………………….. 30,000
Lettuce, green ……………………………………………………………… 4,000
Liver, calves ………………………………………………………………… 7,300
Parsley ………………………………………………………………………. 75,000
Peas, green ……………………………………………………………………. 1,000
Peas, dried …………………………………………………………………….. 1,250
Peach, yellow ………………………………………………………………… 1,000
Peach, dried not stored ……………………………………………….. 4,500
Prune, dried ………………………………………………………………….. 2,000
Spinach ………………………………………………………………………… 25,000
Squash …………………………………………………………………………….. 2,000
Sweet Potato, yellow …………………………………………………….. 5,000
Tomato, ripe …………………………………………………………………… 1,500

Nostalgia of Odors

Of all the sense, that of smell is most closely associated with remembrance. The scent of roses brings back to me with overwhelming vividness the loveliness of an Indian rose garden where I wandered with Her in the fragrance and the moonlight, long ago.

The redolence of cedar, and I see in my mind’s eye a carpenter’s shop which I passed every day when I lived in Syria, with the white-turbaned patriarch working at his bench amid a litter of shavings, while camels, laden with logs from the Cedars of Lebanon, knelt patiently at the door. Sandalwood conjures up a vision of Eastern temples, with shafts of sunlight striking through the murky interiors to be reflected by brazen Buddhas.

Geranium, heliotrope, verbena, lavendar- these show me again the stately white-pillared house in which I was born, with my grandmother bending lovingly over the flowers in her old-fashioned garden. –E. Alexander Powell, Free lance (Harcourt, Brace).