A Study of the Diet in Relation to Caries Activity in 212 Enlisted Men at the Pearl Harbor Submarine Base, Hawaii

Introduction

Is dental disease an expression of a metabolic fault? If so, the establishment of the type of diet best suited to health and efficiency under a given set of conditions is of paramount importance to mankind and certainly none the less to the personnel of the American Army and Navy.

Within the last half century, diet and teeth in Hawaii have undergone radical changes. The once beautiful teeth of the native people are today ravaged by decay. Native foods have been replaced by imported varieties. Newcomers to the islands living on much the same type of diet they had in temperate climates are said to be peculiarly susceptible to an increase in dental caries. If this claim could be substantiated into an indisputable fact and dietary and other factors associated with the increased susceptibility be determined, much progress toward an understanding of the cause of caries would be made.

The recently arrived personnel at the submarine base, Pearl Harbor, afforded an opportunity to make such a study. With the approval of the commanding officer and the enthusiastic cooperation of Commander C. E. Morrow, of the Dental Division, the study of diet and teeth at this naval activity as reported below was made.

Procedure

Examination of teeth.–The dental records of the enlisted personnel who had been examined shortly after their arrival in Hawaii were listed. Among them, 212 of the men represented were available for reexamination. Caries, all fillings, and missing teeth were charted on the standard form used in the Navy. Examinations were made by one of us (G. N. C.) and by Dr. C. E. Morrow, senior dental officer of the base, who had also made most of the examinations on the men on their arrival in Hawaii. In order to get uniformity of results in dental examinations, charts were checked against each other and it was found that interpretations of carious lesions made by the two examiners were identical.

These findings were then compared with those recorded on the first examination. This gave exact information as to the increase in carious teeth, carious lesions, fillings, and missing teeth. In the tabulations, when teeth are spoken of, one tooth is the unit. When defects are spoken of, the unit is one filling, one cavity, or one missing tooth. No effort was made to estimate the extension of a carious lesion. The men were then divided into groups corresponding to the length of their service in Hawaii and according to their ages. The findings in these several groups were tabulated and compared.

Diet analysis.–Quantities and cost of each type of food used in the daily rations for a period of 1 year and the total amount of waste for the same period were furnished by the commissary officer. From the various texts and food tables available,^1,2,3,4 the number of calories per pound of each type of food was obtained and the total calories contained in the amounts of foods used were calculated.

From the references cited, values for the various food constituents, as protein, fat, carbohydrate, calcium, phosphorus, etc., were obtained in terms of 100-calorie portions; and from these and the total calories, the total amounts of the various food constituents in the given quantity of food were determined. Meats vary greatly in their fat content and so in caloric values. In these, the amounts of inorganic constituents were calculated from the amounts of protein contained therein.

To determine average values for the various types of vegetables which were grouped under invoice of provisions furnished by the commissary officer as “fresh, canned, and dried”, the frequency with which each type of vegetable was used was estimated and average values in terms of 100-calorie portions were determined for the various food constituents. For example, 16 vegetables in different proportions are represented in average values of the various constituents in the fresh vegetable group; 5 in the canned, and 3 in the dried. Likewise average values were obtained for cereals, fruits, cheese, meats, etc.

Table I shows the quantity of each type of foodstuff constituting the yearly ration for the entire personnel in pounds and calories. Table II shows the average value of the various types of foods used in the calculations.

Findings

Grouping of men.–The 212 men examined were divided into 3 groups. The first group consisted of 109 men who had been in Hawaii from 6 to 12 months. The second group of 47 men had been in residence from 1 to 2 years, while the third group of 56 were completing from 2 to 5 years of service. It is felt that the dental findings on the first group are significant. In the other two groups they are regarded as merely suggestive due to the small number of men.

Time factor.–Referring to table III, it is shown that 23.5 percent of all defects in the mouths of the first group of men occurred in 6 to 12 months’ time in Hawaii, 30 percent in the second group in 1 to 2 years, and 40 percent in the third group in 2 to 5 years. The average of the ages of the men in the first group is 28.7 years, 27.6 for the second, and 29.7 for the third; the average for all the men being 28.7. The age range for all was from 20 to 40 years. Of the total dental defects found in the mouths of the first group of men, 23.5 percent occurred in 1 year or less, while the remaining 76.5 percent occurred during an average period of 22 years (from sixth birthday to present age). These observations are more significant when it is remembered that after the age of 25 the immunity to dental caries is usually greatly increased.

Table III also shows that 73.4 percent of the men had an increase in carious teeth in 6 months to 1 year and that the average increase per man was 2.74 teeth. This is very high, as it has been estimated that the average increase of dental caries in American children of school age is 1.5 teeth per year. It will be noted that the average increase per man in defects is correspondingly high, being 2.97. Incidence of caries on arrival was 98.15 percent and remained the same. The 2 men of the 109 who had no dental defects on arrival and did not develop any during this period were Filipinos.

Chart I shows graphically the percentages of sound, carious, filled, and missing teeth in the average mouth of the 109 men on arrival in Hawaii and after a residence of 6 to 12 months.

Chart I. Average dental findings in 109 men on arrival and after 6 to 12 months residence in Hawaii.

 

Age factor.–In table IV the men of the first group are divided according to age. It was desired to determine whether the age factor affected our averages. The result failed to show that age was a factor in the increase of caries. The increase in total defects per man for each age group was about the same, being 2.91, 2.73, and 3.31 for groups I, II, III, respectively. The percentage increase in defects per man was 23.3, 23.7, and 23.6.

Taking the full complement of 32 teeth per man it was found that 65.52 percent of all the teeth were sound at the first examination, 3.70 percent were carious, 21.01 percent filled and 9.77 percent missing. On the second examination 58.83 percent were sound, 8.30 percent carious, 21.87 percent filled, and 11.06 percent missing. These figures do not represent a true picture of the increase in carious teeth as in some instances a filled tooth may have developed a new cavity which in turn was filled during the interval between the first and second examinations. Also a tooth may have been both filled and carious. In such a case it was counted as carious and not filled.

It was noted that 68 of the 109 men or 62.3 percent had definite gingivitis in varying degrees, and an additional nine or 8.2 percent had clinical pyorrhea, making a total of 70.5 percent of the men with gingival disease. The ages of 8 of the 9 men with clinical pyorrhea ranged from 30 to 42 years. The other case was a Filipino 24 years of age with 32 sound teeth.

Dietary Findings

Table V shows the average daily quantity distribution of nutrients per man in the diet. Total food prepared, less waste, furnished 3,613 calories, 136.78 grams of protein, 418.11 grams of carbohydrate, 154.95 grams of fat, 0.844 grams of calcium, 1.943 grams of phosphorus, 0.027 grams of iron, and an excess of alkaline elements equivalent to 18.86 cubic centimeters of normal solution. The vitamin A content was found to be 8074.9 standard units and vitamin C, 219.1.

Table VI shows the average percentage distribution of nutrients and it is noted that 25.24 percent of the total calories, 53.69 percent of the protein, and 57.32 percent of acid elements are derived from meat and fish. Vegetables, including potato, furnish 13.73 percent of the calories, 13.71 percent of the protein and 77.94 percent of the excess alkali.

It is noted that the foods which provide the acid excess are meat and fish, eggs, cheese, and grain products. The alkali excess is derived from milk, molasses, vegetables, and fruits.

The largest amounts of phosphorus and iron are derived from meat and fish, being respectively about 40 and 42 percent of the total. Milk, even in the small quantity supplied by the navy diet, furnishes 36 percent of the available calcium while the vegetables supply 31 percent. A large part of the sodium and potassium (not determined) and iron also came from vegetables. Vitamin A was derived chiefly from vegetables and butter while the vitamin C content came entirely from vegetables and fruit. Grain products, sugar, molasses, and vegetables supplied most of the carbohydrate; flesh foods and butter, the fats.

No quantitative data on vitamin B are available. The principal sources are embryos of grain, yeast, vegetables, and fruits. Vitamin D occurs in small amounts in liver, cream and thin, green leaf vegetables. Egg yolk and cod-liver oil are rated as rich sources of this constituent. The principal source of vitamin D, however, as far as man is concerned, is the sun. The ergosterol of the skin secretion is converted into this substance by the sun’s ultra-violet rays.

Discussion

What constitutes an adequate diet? Unfortunately, so far as we know there are no standards in which the condition of the teeth has been a criterion for the adequacy of the diet. Metabolism studies from which present available standards were deduced were in the most part conducted before the significance of vitamins was appreciated, and on a few cases for short periods of time.

For comparison we have taken the dietary study which was conducted by the United States Bureau of Labor Statistics, the United States Department of Agriculture, and by the New York Association for Improving the Poor. Analyses of the diet of the 224 American families were reported by Sherman.¹

Chart II shows the comparison of the two diets from the standpoint of distribution of calories. A rough comparison shows that the Navy ration contains approximately 19 percent more sugar and sweets, 25 percent more meat and fish, 47 percent more butter and fat, 52 percent more vegetables, and 69 percent more fruit than the average American diet. The amounts of egg were approximately the same in the averages of the two diets. The American diet, on the other hand, contains 83 percent more grain and 76 percent more milk products than the Navy ration.

Chart II. Comparison of Navy (submarine base, Pearl Harbor) and American diets (Sherman) in relation to distribution of calories among the various classes of foods.

 

If it is assumed that the optimal diet contains 12½ percent (10-15 percent) of its calories in the form of protein, 37.5 percent in the form of fat, and 50 percent in carbohydrate, the Navy diet closely approximates the ideal in these respects. It would be regarded as relatively high in protein (15 percent of calories) and low in carbohydrate (46.5 percent of the calories), and normal in fat (38.5 percent).

In regard to the mineral constituents, if we accept the allowances for adult maintenance as reported by Sherman, we find that the Navy ration furnishes 24 percent more calcium, 47 percent more phosphorus, and 80 percent more iron than the above allowances.

The vitamin A and C contents are also relatively high. If we regard 1,500 standard units of vitamin A and 15 of vitamin C as minimum daily protective amounts, the Navy ration furnishes more than 5 times this amount of vitamin A and more than 14 times the amount of vitamin C. It must be remembered that vitamin contents of food are variable due to methods of cooking, handling, and other factors. For these reasons too much emphasis should not be placed upon quantitative estimations of vitamin content of the diet. It would appear, however, that this Navy ration contains generous amounts of vitamin A, B, and C. In Hawaii it is reported that the sun shines on an average of 7½ hours daily. This, certainly, should insure at least a sufficiency of vitamin D.

Potential reaction of the average American diet as reported by Sherman is neutral. The Navy ration contains an excess of approximately 19 cc normal alkali. It was surprising to us that this figure should be so low in view of the large amount of fruit and vegetables consumed.

The Becks-Simmonds standard diet.–In a paper entitled “Importance of an Adequate Diet for Health of Teeth and Paradentium”, by H. Becks and Nina Simmonds, appearing in the October 1935 issue of the Journal of the American Dental Association, dietary prescriptions are given quite specifically. In table VII we have compared the composition of the Navy ration with that of Becks-Simmonds diet I, which, they state, “contains adequate amounts of all the minerals and vitamins as well as other dietary essentials.” In addition to the values for protein, fat, carbohydrate, calcium, phosphorus, and iron which the authors reported, we have calculated the acid base and vitamin A and C values for comparison with those of the Navy ration.

Becks-Simmonds diet versus Navy ration.–In every factor except calcium the Navy ration is richer than the Becks-Simmonds specification for growing children, even. As it happened, calcium values assigned to some of their foods, particularly cereals and bread, are from two to three times higher than those used in our calculations. If their calcium values for bread and cereals alone were used, the calcium content of the Navy rations would be appreciably increased. However, according to the Becks-Simmonds scale, adult diets containing from 0.3 to 0.4 gram of calcium are appraised as fair; from 0.4 to 0.5 gram as good; and 0.7 gram or more as excellent. The calcium value of the Navy ration is well within their optimum range. It is disappointing after one has read through pages of tables, menus and case histories to find at the very end of the paper a statement : It should be emphasized that as yet it is not known whether these are caries prevention diets. The authors state that they hope their recommended diets will prevent caries as well as other dental disease, and warn that to get the best result the diets must be faithfully followed and good oral hygiene practiced.

Becks-Simmonds diet versus Mooseheart.–We do not, however, share the same optimism or even hope of Becks and Simmonds that their diet will prevent or arrest caries. The diet of the average sailor at Pearl Harbor is optimum plus, according to their standards, and he lives in a sun-flooded environment. Notwithstanding, his rate of increase in dental caries is almost twice as great as that of the average American child. Perhaps climate makes the difference between Hawaii and the mainland. Turning to the latter (Mooseheart) we find that a diet containing approximately 1 quart of milk (B.-S. diet I contains three-fourths of a quart); 16 ounces of vegetables (B.-S. diet I contains 10 ounces); 8 ounces of fruit (B.-S. diet I contains 3½ ounces); 1 egg (B.-S. diet I contains 1 egg); resulted in 1 year, in active tooth decay in 83 percent of a group of 264 children, each of whom developed an average of 1.9 new cavities. The Mooseheart diet furnished 1.4 grams of calcium (B.-S. requirement is 1 gram per child), and 2 grams of phosphorus (B.-S. requirement is 1.227 grams). The addition of a pint of orange juice and the juice of one lemon retarded and arrested caries in most of the children, only 33.7 percent, showing an increase. The total amount of milk the children drank while taking the orange and lemon juice was less than they previously took. The net result as far as calcium, phosphorus and vitamins are concerned was a slight increase in calcium and phosphorus, an appreciable increase in vitamin A, and a tremendous increase in vitamin C. The orange and lemon alone furnished approximately 392 units of vitamin A and 294 units of C. The amounts of these vitamins are about one-fourth of the daily protective dose (1,500 standard units) of vitamin A, and more than 19 times the vitamin C requirement. There was no increase in vitamin D.

The more than 50 percent reduction in the rate of increase in tooth decay in these children while on the diet supplemented with the increased amounts of orange and lemon juice is convincing evidence of the presence of a caries-inhibiting factor or factors in these foods. Is this factor vitamin C? Unfortunately, Hanke and associates did not run a control group which would have proven this point beyond question. The fact, however, that outbreaks of scurvy, the disease that results from a deficiency of vitamin C, is not associated with an increase in dental caries, is irrefutable evidence that this food factor does not control the body mechanism which determines immunity or susceptibility to tooth decay. According to the Becks-Simmonds specification for calcium and phosphorus, the Mooseheart diets were par excellence, the ratio of these elements in the three diets being well within the so-called optimum range. Likewise, all other food factors graded by the Becks-Simmonds standard rated more than optimum. What, then, is to be the criterion for measuring the adequacy of a diet consisting of ordinary food-stuffs and containing all of the known essential food constituents in adequate, if not generous amounts?

Acid-base balance.–As was shown by one of us (M. R. J.)⁷ analyses of the 3-diet periods of 1 year each on the 264 children studied at Mooseheart furnish a promising clue. If the percentage of children showing an increase in caries during the 3-diet periods is plotted against the excess of alkali in the diets, an inverse relationship between these values is apparent. In other words, as the potential alkalinity of the various diets increased, the susceptibility to dental caries decreased. All three diets contain an excess of alkaline elements. The amounts were found to be 25 cc of normal solution during the control period; 55 cc during the test period (16 ounces of orange juice and the juice of one lemon added) and 22 cc during the recheck. The corresponding percentages of children who developed new cavities during these periods were 78, 34, and 83. The almost true diagonal line resulting, if extended, crossed the base line at a point near 80, which indicated that, if these diets, containing, as they did, amounts considered generous of the various known essential nutrients, had also yielded an excess of alkali equivalent to 80 cc normal solution, the decay process would have been completely arrested.

Analyses of diets reported by other investigators show tremendous differences in acid-base values, while the majority yield comparable values for the known essential constituents. It was interesting to find that all of the diets analyzed were either neutral in potential reaction, or alkaline. The inverse relationship between the incidence of caries and potential alkalinity of the diet that was observed in the Mooseheart diets was also found.

In Hawaii, so far as is known, every type of vegetation (including seaweeds) which grew here before the arrival of visitors 100 years ago yielded an alkaline ash. Fish was the main source of the acid elements. The diet as a whole was high in potential alkalinity and although it undoubtedly contained adequate amounts of all essential food: constituents (the large stature, fine physique, and beautiful teeth of the native people attesting), the absolute amounts of calcium and phosphorus were probably low if measured by present-day standards. These observations have been duplicated in Samoa and other Pacific islands.

Relative values of foods.–The potential reaction of any diet depends upon the relative proportions of its various constituents. For instance, a strictly vegetarian diet may be either acid or alkaline in character depending not only upon the relative proportions of grains and “vegetables”, but upon the type of vegetables composing it. It is perfectly possible for a diet containing a large amount of grain to be high in potential alkalinity, if, among the vegetables, is included a certain percentage of the leafy variety. Grains and greens supplement one another in many ways. Likewise, a diet consisting essentially of flesh may be potentially alkaline if it contains a certain percentage of blood and fat. The first choice of animal tissues of wild carnivora is blood which is potentially alkaline in reaction. Muscle, which contains an excess of acid elements, is the least desired. The Eskimo supplies a large percent of his caloric needs with blubber. For this reason the absolute amount of ash in his diet is probably low if measured by accepted standards. He drinks blood and eats the partially digested roots, shrubs, etc., which he obtains from the stomach of deer. The potential reaction of his diet is unknown.

Becks and Simmonds list certain vegetables as interchangeable in their diets. One such group contains corn, peas, carrots, greens, cauliflower, string beans, turnips and onions. Servings of these foods (approximately one-half cup) vary in excess acid-alkali content from 2.7 cc acid (corn) to 27 cc of alkali (spinach). If the potential reaction of a diet is a factor in maintaining the mineral balance in the body, a “workaday” knowledge of the acid-base balance of foods is of prime importance to the civilized world. Whether it is the prime factor in controlling that body mechanism which determines susceptibility and immunity to tooth decay is not proven. That it may be cannot be gainsaid; and if it is, corn and spinach cannot be interchanged successfully in any diet.

The civilized world is confronted with a nutritional problem of first magnitude. Tooth decay is rampant in many places and on the increase the world over. We may be certain that the nutritional fault which expresses itself in decaying teeth is leaving its imprint elsewhere in the body. It works in a subtle and insidious way slowly undermining resistance to diseases of all kinds. Among the 212 men examined for this study 208 had active tooth decay. The average number of defects (cavities, fillings, and missing teeth) per man was 14.78. The rate of increase in caries is alarming. Can it be stopped, and if so, how?

Suggested changes.–As has been shown, the Navy ration rates as par excellence according to generally accepted standards. It is low in potential alkalinity, a factor which is disregarded entirely by some,^8,9 or considered unimportant by others.^10,11

Chart III shows graphically the magnitude of changes in the various constituents of the diet resulting from the replacement of certain acid ash with alkaline ash foods of comparable caloric values. Milk and meat are protein rich foods. Milk is potentially alkaline and meat acid. By reducing the meat in the diet 300 calories (about one-third pound) and increasing the milk 300 calories (about 14 ounces) the potential reaction of the diet is appreciably increased and other changes which appear to be desirable introduced. Similar changes result from the substitution of raw vegetables for 100 calories in the form of bread (1 medium slice); and molasses or cane syrup for 100 calories of refined sugar (2 T). The net results of such substitution is a slight reduction in protein and fat; a slight increase in carbohydrate; an appreciable increase in phosphorus and iron; a large increase in vitamins and calcium; and a net increase of 396.6 percent in potential alkalinity, or from 18.86 cc normal solution to 93.66 cc. Whether such changes in the above diet would prevent and arrest dental caries in the men is unknown.

Chart III. Percentage changes in food factors obtained by replacing 300 meat calories with 300 from milk; 100 bread calories with 100 from raw vegetables; 100 sugar calories with 100 from molasses.

 

Diets in Hawaii consisting essentially of fruits, roots, tubers, and other vegetables with moderate amounts of fish, meat, and egg with or without milk are associated with sound teeth. The dietary factor or factors that inhibit the decay process is apparently in fruits and vegetables. The almost universal freedom from enamel caries and extensive atrophy of the alveolar process observed in the adult Samoans whose diet consisted of fruits and vegetables with insignificant amounts of fish, indicate a certain optimal limit of the decay inhibiting factors. In excess, this factor results in deterioration of the bone structure of the human body. The alveolar process is a transitory tissue. It is apparently the first to succumb to the caries inhibiting factor. Sound teeth become loose and fall out. It may be that fruits and vegetables contain a hitherto unknown substance which is specific for dental health. Until that substance is discovered, the potential reaction of an otherwise “adequate” diet appears to be not only our best, but only guide for the control of dental disease.

Cost.–Table VIII shows the composition and cost of the Navy ration and suggested changes. The milk used to replace meat may be either fresh, evaporated, or dried. In calculating the cost we have used evaporated, estimating the cost at the price listed on the invoice of provisions furnished by the commissary officer. It will be noted that the total cost of the ration with the suggested changes introduced is decreased 1.82 cents.

Summary

A group of 212 enlisted men from the submarine base at Pearl Harbor, Hawaii, was examined and the differences in their dental condition on arrival and after 6 months to 5 years of residence in Hawaii were recorded. Examination showed progressive increase in dental defects paralleling time of service in Hawaii, the percentage being 23.50, 30.06, and 39.97 for the men who had been in residence 6-12 months; 1-2 years, and 2-5 years, respectively. The percentage increase in total defects per man for the 6 months’ to 5 years’ period was 28.80.

The incidence of caries among the men on arrival was 97.6 percent and on the second examination, 98.1 percent. Age did not appear to be a factor in the increase in caries. In three groups of men of different ages who had been in residence from 6-12 months the average number of new defects per man was 2.9, 2.7, and 3.3, for the 20- to 25-, 26- to 30-, and 31- to 40-year-old groups, respectively. In the same order of age groups the percentage increases in defects per man were 23.30, 23.70, and 23.57.

The diet consisted of approximately 17.2 ounces of meat; 1 egg; 9 ounces of whole milk; 1⅓ ounces of butter; 11 ounces of bread and other grain products; 2½ pounds of potato and other vegetables; 1 pound of fruit; 4 ounces sugar and syrup, and adjuncts. The diet furnished generous amounts of protein, calcium, phosphorus, iron, and vitamins if measured by accepted standards, and yielded an excess of 18.86 cc normal alkali. The excellence of the Navy ration according to accepted standards, with extensive decay suffered by the men during their short residence in Hawaii, suggests the existence of other factors. In Hawaii diets which contain no milk or grains but are rich in fruits, roots, tubers, and other vegetables are universally associated with sound teeth. It appears that the need for fruits and vegetables in the human diet parallels warmth and exposure to sunshine and the 3½ pounds of these foods in the Navy ration were insufficient under local conditions. There appears to be a factor (or factors) in fruits and vegetables, which, if present in insufficient amounts, results in enamel decay (caries and odontoclasia); and in excess, in atrophy of the alveolar bone. This cannot be attributed to any of the factors which are generally associated with tooth decay (calcium, phosphorus, vitamins). Fruits and vegetables as types of food contain an excess of alkaline elements over the acid, but the amounts of alkali excess vary tremendously in different varieties. Thus, the potential alkalinity of the diet depends not only on the quantity therein, but kinds. Until this unknown factor which inhibits tooth decay, on the one side, and in excess results in bone atrophy, on the other, is discovered, it appears that the potential alkalinity of an otherwise adequate diet is not only our best but the only guide for the control of dental disease.

Changes planned to increase the potential alkalinity of the diet were suggested and the various alterations occurring simultaneously in other food factors were discussed.

 

References Cited:

1. Sherman, H. C., Food Products, The McMillan Company, 1914.
2. Sherman, H. C., Chemistry of Food and Nutrition, The McMillan Company, 1923.
3. Rose, Mary Swartz, A Laboratory Hand-Book for Dietetics, The McMillan Company, 1917.
4. Bradley, Alice V., Tables of Food Values, The Manual Arts Press, 1931.
5. Becks, Herman and Simmonds, Nina, J. A. D. A., 1935 October, 1724.
6. Hanke, M. T. and the Chicago Dental Research Club, Dental Cosmos, 1933, 75, 933.
7. Jones, M. R., Dental Cosmos, June 1935, 77, 535.
8. Cowgill, G. R., Dental Cosmos, 1934, 76, 223.
9. Mellanby, May, Diet and Teeth, Medical Research Council Special Report Series No. 191. 
10. Boyd, J. D., Drain, C. L., and Sterns, Genevieve, J. Biol. Chem. 1933, 103, 327.
11. Koehne, Martha, Bunting, R. W., and Morrell, Elsie, Amer. Jour. Dis. Child., 1934, 48, 6.