Fitness

Studies have been made of the mucous membranes of animals fed different amounts of vitamin A. It was found that harmful bacteria were always present. The animals deficient in this vitamin had millions of bacteria feeding off their dead cells, however, and 98 per cent showed infections; those fed adequate vitamin A harbored few bacteria and showed no infections. Microscopic studies of the mucous membranes of hundreds of humans dying from accidental death or infection show similar correlations; there is freedom from an accumulation of dead cells and from infections; or the number of dead cells parallels the severity of the infections. Furthermore, the liver tissue of adults meeting accidental death has been found to average 20 times more vitamin A than that of persons dying from infections or infectious diseases.

The absorption of adequate vitamin A will correct deficiency symptoms, the length of time depending on the amount of vitamin given, the severity of the deficiency, and the tissues affected. Studies have shown that improvement in mild eye symptoms has occurred in as little as one hour after 50,000 to 100,000 units of vitamin A have been given. On the other hand, when the deficiency is severe and the vitamin dosage small, normal night vision may not be recovered for weeks or even months. In correcting mild visual abnormalities, the vitamin need merely be absorbed into the blood and carried to the ocular fluid. Recovery from corneal ulcers or changes which have occurred in the skin and mucous membrane, however, means that new tissue must be grown to replace the unhealthy tissue produced during the deficiency. It has been reported that the dryness of skin has disappeared and the lubricating oils have returned in as short a time as two weeks after dietary improvement; it has been my experience, however, that a longer interval is needed for recovery.

Some years ago a physician referred to me a woman whose face was covered with hundreds of large warts. A number of reports had pointed out that warts often disappeared when the diet was made adequate in vitamin A. I therefore planned a nutrition program for her, making it as adequate in all nutrients as I possibly could, and suggested that she take 100,000 units of vitamin A daily. When her skin showed no change after four months, we both became discouraged. A week later she came to see me, greatly excited. Not a wart remained, nor has one returned since then. This case convinced me that it takes approximately four months for unhealthy tissue to be replaced by healthy tissue, although probably wide individual variations should be expected.

Aside from helping to maintain normal vision and resistance to infections, adequate vitamin A is essential to the development of bones and the tooth enamel, good appetite, normal digestion, reproduction, lactation, and the formation of both red and white blood corpuscles. It appears to delay the onset of senility and to promote longevity. Vitamin A also has a profound influence upon development before birth.”

The National Research Council has recommended that an adult have 5,000 units of vitamin A daily to maintain health. A table of food analysis would show that the richest sources of carotene, averaging about 12,000 units per serving (100 grams), are green leaves such as chard, kale, spinach, and other greens. Even one serving of string beans, broccoli, carrots, yellow squash, apricots, sweet potatoes, or yams would supply 5,000 units, all one supposedly needs for a day. A serving of tomatoes, peas, unbleached celery, lettuce, and asparagus averages nearly 2,000 units. Except for apricots, most yellow fruits offer little more than 400 units per serving. Vegetables which have lost their color or have never been green lack this vitamin.

Such a table would show that liver may be extremely rich in vitamin A and that kidneys and sweetbreads contain appreciable amounts. Since this vitamin is not stored in muscles, such meats as roasts, chops, and steaks lack vitamin A. Eggs and butterfat contain it, the amount depending upon the animals’ food. Whole milk varies from 500 to 7,000 units per quart but usually averages 2,000 units. Most of the vitamin A may be destroyed by oxygen when milk is homogenized, although this problem appears not to have been studied. Winter butter, produced when the cows are given dry feed, may contain only 2,000 units per pound, whereas summer butter averages 12,000 units. Butter substitutes usually have 12,000 units of the vitamin added per pound.

Fish-liver oils are the richest commercial sources of vitamin A. The vitamin content of livers, however, depends on the animals’ food and age. Aside from polar-bear liver, the richest source ever determined was the liver oil of a python estimated to be 100 years old when killed in a London zoo. Halibut-liver oil is richer in vitamin A than is cod-liver oil because halibut is elderly when marketed, whereas cod is a mere adolescent; the halibut has had more years to eat green sea algae. For the same reason beef and mutton liver usually contains more vitamin A than do calf and lamb liver.

Scientists as well as laymen have been led to the conclusion, from studying tables of food analysis that we easily obtain all the vitamin A we need from foods. Surveys in which thousands of persons have kept records of foods eaten for a month or more, however, show that three-fourths of our population obtains only about 2,000 units of vitamin A daily. In these surveys the assumption has been that all the vitamin A obtained from food is absorbed into the blood.

Unfortunately, there is many a slip between the lip and body cells. Vegetables analyzed in a laboratory perhaps grew on excellent soil and received the optimum amount of rain and sunshine; possibly they contained a hundred times more vitamin A than those grown under less ideal conditions. Carrots, for example, have been analyzed which contain no carotene whatsoever. Losses of the vitamin occur during shipping, storage, freezing, canning, and cooking. Milk from cows feeding on a luxuriant growth of alfalfa has been found to lack vitamin A; the alfalfa, when analyzed, was found to contain no vitamin E, necessary to prevent the destruction of vitamin A in the body. The liver you perhaps ate, believing that you were obtaining vitamin A, may have come from an animal whose only food for months was dried hay.

Even if vegetables are rich in carotene, there is no insurance that it will be absorbed. The carotene in vegetable foods is held inside cell walls made of cellulose, a substance which cannot be digested by humans. Carotene cannot dissolve in water; therefore it cannot pass through these walls. Only when the cell walls have been broken by cutting, chopping, cooking, or chewing is it freed to pass into the blood. Approximately 1 per cent of the carotene from raw carrots has been found to be absorbed,” whereas cooking increases the absorption from 5 to 19 per cent.’ Studies show that the absorption of carotene from most vegetables averages from 16 to 35 per cent; the softer the texture, the larger the amount of carotene which reaches the blood. Presumably all the carotene is absorbed when vegetables are liquefied or juiced, but if the juice is not drunk immediately, much of the vitamin is destroyed by oxygen.