The Role of Iodin in the Body

Iodin Necessary for Metabolic Balance

This Important Element is Discussed by

Emory W. Thurston, Ph. G., Ph. Chem., Ph. D. in

“THE ROLE OF IODIN IN THE BODY”

 

                Despite long research and observation, it is only recently that much actual knowledge has been obtained as to the action of iodin and its compounds in the human body. While traces are found in the blood, nerves, and various glands, the normal ovaries and uterus contain only slightly less than the thyroid, where the element is most abundant. Of the hormone thyroxin, iodin forms 65%.

Kendal of Rochester, Minnesota, has found that of the total iodin of the thyroid gland, 60% is in the form of diiodo tyrosin and 16% as thyroxin, there being no inorganic form of the element in the gland. Among some of the factors which apparently interfere with the proper utilization of iodin in the system are diets consisting of a high percentage of fat, or protein, or both. The normal thyroid stores about 25 milligrams of iodin, and the body contains about 10 milligrams more, or a total of approximately one-hundredth as much as of iron.

Blood Iodin can be Determined

The determination of the blood iodin presented tremendous difficulties, but was finally accomplished by Von Fellenberg in 1923. He developed an adequate micro-method. The average amount of iodin in the blood of healthy individuals examined in the Middle West is about 12 gammas per 100 c.c. of blood. During the winter, the level falls; in women, during pregnancy and menstruation it rises somewhat. Due to the minute amount of the element in the blood, it was necessary to designate a special unit, the gamma. This unit, or microgram, is 0.001milligram. Thus 100 c.c. of human blood contains normally about 0.012 milligram, or a total amount for the entire blood volume of considerably less than 1 mgm.

Estimates as to the amount of the element required daily to maintain normal health and vigor vary considerably, but from the data gathered by Swiss and German investigators several years ago, and which seem conservative and reasonable, it appears that approximately 6.00 milligrams a day should be ample. The principal periods of demand are during puberty, pregnancy, the menopause, and infections. Women require considerably more than men.

Iodin More Abundant in Sea Coast Soil

Near seacoasts, the soil is usually fairly well suppliedwith iodin, except where crops are rotated rapidly by market gardening, and only stable manure is used as fertilizer. Since iodin salts are very soluble in water, rains and irrigation soon leach most of the salts from the soil. In several sections of this country, soil iodin deficiency is notorious. This is especially true of the Great Lakes and Rocky Mountain regions, the Central Plateau (Utah, Idaho, Montana, etc.), and the Pacific Northwest. Even where actual deficiency is not so pronounced, disinclination of most people to consume iodin-bearing foods, and a predominating carbohydrate diet tend to produce a condition of actual deficiency.

The foods that contain iodin to any appreciable extent are given in the following list. The amounts of element indicated, however, varies considerably in different areas. For instance, a careful examination of several samples of milk and eggs purchased in grocery stores in Chicago failed to disclose a trace of iodin, and samples of timothy and clover hay as fed to dairy cows gave the same result. The writer has examined alfalfa hay from several sections of Southern California and found a surprising variation in the iodin content. Usually it was noticeable by its rarity.

Iodin Content of Foods

(Market specimens, from commercial sources, where no special fertilizers or feeds are used)

Kind of Food                                                                                      Parts per million

Lettuce  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    .006

Cabbage  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    .006

Carrots    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .007

Potatoes (whole)     . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .018

Apples     . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .007

Oranges (whole)    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .015

Figs (dried)    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .    .069

Wheat   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .003

Milk     . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .012

Eggs     . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .022

Fresh water fish (average)     . . . . . . . . . . . . . . . . . . . . . .      .020

Cod      . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .240

Halibut    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     .250

Oysters and clams (average)    . . . . . . . . . . . . . . . . . . . . .   1.200

Lobster    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1.380

Prepared Sea Plants     . . . . . . . . . . . . . . . . . . . . . . . . . .   900.000

Numerous experiments with laboratory animals have demonstrated that after infection with Bacillus typhosus, the thyroid gland enlarges and shows evidence of intense cellular secretion. The ingestion or organic iodin in massive doses enables the animals to build sufficient resistance to combat the infection, while the controls almost invariably succumb.

Iodin, One of Ten Elements Essential to Health

McCarrison showed in 1922 that test animals confined in dirty and overcrowded cages, developed goiter, while those kept in scrupulously clean cages of the same dimensions and fed upon an identical diet continued in perfect health. Since the food supply—and therefore the iodin supply—was the same, it follows that the unhygienic surrounding called for additional amounts of the element as a protective factor. A sufficiency may become an insufficiency in the presence of unfavorable surroundings. If an additional supply of iodin in organic food form is provided, goiter does not develop despite the dirty cages.

Iodin is one of the “big ten” elements, i.e, those known to be absolutely essential to good health, if not to life itself. From a physiologic standpoint it activates and stabilizes the endocrine glands, and is responsible for normal nerve impulses, mental activity, and intellectuality; as well as the proper metabolism of calcium, phosphorus, and the starches. Probably it also increases immunity to disease.

A deficiency of the element in the diet may cause lowered vitality, inability to think logically, loss of control of glands and muscles of the mouth (resulting in contortion and drooling), defective formation and structure of the teeth, tendency to obesity, cretinism, faulty habits in general, loss of tone in the circulatory system, as well as in other tissues, and slow or defective sexual development. Many cases of epilepsy have shown degenerative changes in the thyroid tissues. Whether this latter condition was due to actual deficiency of iodin in the diet has not yet been determined.

There is constantly accumulating evidence that the inorganic form is not the correct method of administering iodin. It is of doubtful efficiency, and is impractical from many viewpoints. Resurveys following the use of iodized salt, and the iodization of public water supplies over a period of years, have not shown any material decrease in the incidence of goiter.

The following is an excerpt from a statement recently made by Dr. William Weston of the United States Department of Public Health:

“After a most diligent and careful search of the literature I have failed to find a single incidence of iodin poisoning where the diet contains an enormous amount of iodin in its organic state. Perhaps Lunde is correct in his explanation. He writes: ‘Investigations have shown that when inorganic iodin is supplied it leaves the body quantitatively in a rather short time (less than 24 hours), mostly through the kidneys. The organically bound iodin of food stuff, however, is set free only slowly in the organism, and a longer time elapses before it leaves the body, it seems reasonable to assume that organic iodin compounds play an important part in the organism, since they are present in all tissues. A number of investigators have, therefore, emphasized the great importance of naturally bound iodin in goiter prophylaxis instead of the inorganic form.’

“It is the feeling of pediatricians in an extensive section of the country that goiter is distinctly on the increase in young children. This observation suggested the importance of analyzing the available milk supply.

Organic Iodin More Easily Assimilated

“Where people do not have goiter, or other manifestations of iodin deficiency, they receive iodin in its organic relation as it exists in milk, vegetables and fish. There are one or more elements in this organic combination that not only determine the rate of assimilation but its availability as well.”

Many individuals seem to get along on a very small amount of iodin. Their scanty supply, however, may give rise to many obscure “border-line” symptoms without definite pathology. The examination of prospective soldiers during the draft in 1917 demonstrated that a surprising number of the men examined had definite evidence of iodin deficiency (thyroid disorders) and was the first intimation of the alarming extent to which this condition existed. Over 90% of the men examined who showed thyroid disorders had carious teeth. Many surveys of school children have been made in various localities notably deficient in iodin. Marine and Kimball, in 1917, found that in the City of Akron, Ohio, 56% of the girls from the fifth to the twelfth grade in school, had enlarged thyroids. Olin (1924) found in an extensive survey in Michigan, 40% of the boys and 53% of the girls were afflicted. Of these children. 90% suffered more or less from dental caries.

Conclusion        

Iodin must be considered a food element of tremendous importance. Its lack in the diet must be supplied if the animal mechanism is to function normally. Inorganic forms, while they may be of great value as stabilizers of disturbed thyroid function, are too uncertain to be relied upon.

Strictly organic Iodin as it occurs in food from is the only proper source of the element. If normal foods are lacking in proper amounts of iodin they must be supplemented by natural sources which are rich in the element.

In addition to metabolism tests, the determination of the iodin is a valuable indicator of thyroid function. Fluctuation in the amount during the course of thyroid disease becomes very significant. This blood iodin is increased in hyper function, and decreased in hypo function of the gland. Apparently, the iodin level in the bloodstream is definitely controlled by thyroid activity. If simultaneous determinations of the content of the element in the blood and urinary excretions are correlated with a proper metabolic test, the findings are comparable to the estimations of blood and urine sugars in diabetes mellitus. Lack of iodin causes thyroid disturbance, and dental caries is almost invariably an associated symptom. Iodin in food form is essential as a catalyst for stabilizing the calcium metabolism.

EMORY W. THURSTON,

Los Angeles, California

 

 

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