Taro and Sweet Potatoes Versus Grain Foods in Relation to Health and Dental Decay in Hawaii

The Ancient Hawaiians

Captain Cook, who landed in Hawaii in 1778, estimated the population of the islands at 300,000 to 400,000. The people were brown-skinned, tall and had great muscular strength. Dental decay and many other diseases to which they are peculiarly susceptible today were rare or unknown. They wore the “tropical dress” of primitive people and lived in grass houses. They fished, swam and traveled far and wide over the Pacific Ocean in their outrigger canoes. Their principal food crops were taro and sweet potatoes, which they cultivated. These, with fish and other sea foods, constituted perhaps 95 per cent of the diet. Milk and grain foods were unknown. Fruits and vegetables were not abundant. Even the banana, which is so common today, was a delicacy as late as seventy-five years ago and was reserved for Chiefs.

Hawaii from 1778 to 1932

Table I was compiled by Mrs. Helen S. Chapman and was published in the June 1933 number of The Queen’s Hospital Bulletin. It shows the population changes in Hawaii from 1778 to 1932.

With the development of the sugar and pineapple industries, laborers were imported into the islands in large numbers from China, Japan and the Philippines as well as from European countries. All who came brought their own cultures. Most of the laborers of all nationalities were farmer folk, and in their native lands were used to plenty of vegetables and fruits. Most of the Japanese came from districts where the sweet potato was the principal carbohydrate food. Polished rice in those days was a luxury and was associated with wealth. The Filipino was even more blessed, because food in abundance was his for the gathering; many kinds of tropical fruits, plantains, mushrooms and greens grew wild, and unlimited amounts could be had for the taking. They, too, ate sweet potato and taro in quantity. Conditions here, however, were different. Hawaii, to them, was a land of wealth, and they could eat polished rice, which they had been accustomed to use sparingly, without stint. They liked it and it was found to be the cheapest food they could buy. There was little space and less time for the growing of potatoes and other vegetables and the chickens must have some green food. The family ate rice and more rice. The children learned to eat bread in school. It is said that the Orientals eat 85 per cent of the bread consumed in Hawaii.

What has happened to the Hawaiians? They are kindly in nature and generous to a fault. They have mixed with and married into all national groups, and have assumed the food habits and customs of their visitors. Their susceptibility to diseases of all kinds was high, due probably to a lack of natural immunity, and the population has dwindled at an astounding rate. Grain foods have to a great extent replaced taro and potato in their diet.

Morbidity and Mortality

Mrs. Chapman,who has made a study of climate and disease in Hawaii, writes: “It is exceedingly difficult to find a combination of conditions (temperature, humidity and wind velocity) in Hawaii producing an ‘effective temperature’ outside the comfort zone.”… “Except for the small Cape Bird Islands off the coast of Africa, and possibly the Fiji Islands (which have cyclones and high humidity) and a few other small isles in the South Seas, there is no place in the world with a climate even approaching that of Hawaii. With Mother Nature smiling so benignly upon these islands, why need disease exist here to the extent it does?”

 

Odontoclasia and Dental Caries

Odontoclasia differs from dental caries in three important respects: (1) It is confined almost exclusively to the deciduous teeth. (2) It occurs on all surfaces of all teeth and has a special predilection for the lingual surfaces of the upper incisors, the occlusal surfaces of molars and tips of cusps–the regions which ordinarily are relatively immune to caries. (3) It progresses over the surface of the tooth in broad lines rather than boring into pits and fissures as does caries. Odontoclasia is probably an exaggerated form of caries. The underlying causes of the two types of dental decay appear to be the same. Differences in expression can be explained on the basis of greater intensity of the decay process and immaturity of the tooth in infancy and youth. Though odontoclasia is rare even in newly erupted permanent teeth, if the decay process is sufficiently active the hardest of adult teeth may be completely ravaged by this type of decay in a short period of time.

Dental Decay in Relation to Bone Development² 

As has been previously reported, tooth decay in infants and children of all ages is endemic in Hawaii. In a group of fifty Oriental plantation babies who were studied intensively from birth to two years of age by means of roentgenograms of the long bones and teeth as well as clinical examinations made at frequent intervals, 80 per cent had odontoclasia at one year of age and 98 per cent at two years. Development of the long bones, as indicated by the number and size of bone centers present, appeared in many cases to be in advance of the chronologic age (to be reported). There were two cases (twins) of rickets at four months of age. Both developed odontoclasia in spite of the fact that one got cod-liver oil and the other did not. Odontoclasia appears to be more rampant in the active, run-about child who plays out of doors than in the more sluggish “in-door” one. It is frequently associated with “spurts” in calcification of the long bones.

Dental Decay–A Systemic Disease?

Odontoclasia is an exaggerated form of tooth decay which commonly occurs in the newly erupted teeth of breast-fed babies of the laboring population in Hawaii. So rampant is the decay process that it is sometimes necessary for a baby to have one or more teeth extracted before he is one year of age, and before he has tasted any food other than mother’s milk. Dental decay is almost universal in the Hawaiian-born children of grain-eating people of all nationalities, regardless of the fact that the teeth of parents of many are entirely free from decay. It rarely occurs in those who do not eat grain foods and use taro and potato in generous amounts.

A condition simulating decay has been observed in the enamel of the unerupted teeth of infants who have died of starvation and beriberi, and in the teeth of a full term but unborn fetus whose mother died of nephritis. In all cases it has been associated either with a known state of acidosis (starvation and nephritis) or with maternal diets which contained an excess of acid-forming elements (meat, fish, eggs and grains). A number of factors appear to play a part in the activity of the decay process. Among these are diet, age, development, climate and disease. The above facts support the contention that tooth decay is primarily systemic in origin. We regard it as a sensitive, and perhaps the best indicator of community health in Hawaii.

Certain Food Factors in Relation to Dental Decay

(1) Carbohydrates. The Polynesians throughout the Pacific area have from time immemorial been large consumers of carbohydrate foods–roots and tubers. It is estimated that from 60 to 75 per cent of the calories of the diet of the old Hawaiians were in the form of taro root and sweet potato. Fish furnished the protein of their diet. They did not use milk, beef or grains. Their diet was not only rich in carbohydrate, but soft and pappy in consistency; yet throughout the centuries these people maintained their fine physiques, broad dental arches and freedom from tooth decay. The introduction of grain foods in the tropics and their substitution for roots and tubers have been accompanied by an increase in the incidence of respiratory and blood-vessel diseases. In spite of their splendid heritage, the teeth of Hawaiian babies of today are often ravaged by decay before they completely erupt. The type of carbohydrate in the diet, rather than amount, appears to be the important factor in maintaining sound teeth in Hawaii.

(2) Vitamin D. Honolulu has enjoyed daily for the past twenty-five years an average of seven and one-half hours of tropical sunshine, the richest known source of vitamin D; yet during that time the incidence of dental decay has increased rapidly. Eggs, which are also rich in vitamin D, are a common article of food today. Cod-liver oil was used systematically in the baby clinics, kindergartens and schools for years without any detectable beneficial effect upon the teeth of the children. The conclusion is inevitable that vitamin D in large amounts under conditions existing in Hawaii does not prevent or arrest dental decay.

Types of Diets in Relation to Dental Decay in Various Regions

The different effects of various types of foods on man in different parts of the world are due, we believe, to differences in food requirements which are to a great extent determined by climate and activity as well as age and systemic condition. The human race subsists largely on carbohydrate foods–roots, tubers and grains. As has been pointed out, roots and tubers are indigenous in the tropics and grain foods in the temperate zones. Though they are generally regarded as interchangeable as sources of carbohydrate, they should not be, because roots and tubers act as an alkali when they are burned in the human body, and are needed, apparently, to balance the physiologic effect of a warm climate. Grains, on the other hand, yield an excess of acid elements which are well tolerated in cold climates, but in the tropics create an imbalance in the systemic complex toward the acid side. Neither grain foods nor potatoes grow in the arctics, and man thrives best in the extreme and habitual cold when he subsists on flesh foods. The introduction of grain foods into the arctics and tropics has been associated with physical deterioration of the people, an increase in the susceptibility to diseases of all kinds and increase in the incidence of dental decay.

Mellanby has reported the existence of a toxic substance called “toxamin” in grains, particularly oats, which interferes with calcification of bones and teeth. She claims that the effect of the “toxamin” is overcome by vitamin D. Clinical experience does not support the experimental studies. Oatmeal has from time immemorial been the principal carbohydrate food of the people of the island of Lewis in the Hebrides, where the winters are long and cold and the summers short. The people live in “black” houses, the walls of which are said to be four and five feet thick, with only one opening. The diet of the people consists essentially of fish, eggs, potato and oats. It is rich in protein and probably potentially acid in reaction. It is suited to the climate and the people are famed for their fine physiques and “beautiful” teeth.⁴

There are large regions throughout the temperate zones where grain foods have from time immemorial been the principal carbohydrate food–the “staff of life”–of millions of people. In cold inland districts the vitamin D content of the diet is probably low, such as in Russia and North China, where wheat grows luxuriantly and constitutes the principal food of the people. Those who subsist on native foods are said to be physically strong and their teeth free from decay. On the contrary, the vitamin D content of Hawaii’s sunshine has been wholly ineffective in neutralizing the toxamin in rice, even though it is said to contain the least of this substance of all the grains. The association of dental decay with grain foods the world over may be due, not to a fault, as such, in the grains, but to their excessive use out of their natural habitat.

In addition to the above foods, meat, fish, fruits and vegetables are used regularly, but the amounts are difficult to determine accurately, and are probably comparable today to what they were 150 years ago (meat excepted).

Though rice is superior to either taro or potato as a source of protein, it contains less calcium, phosphorus and vitamin. They are all rich in carbohydrate, and relatively poor in minerals. The outstanding difference between grain foods and roots and tubers is in their acid-base content. The ash from one pound of raw potato contains an excess of alkali equivalent to 30 cc. normal solution, while a pound of raw rice yields approximately 42 cc. of acid. In terms of calories, 1000 calories in the form of rice yield 26 cc. acid, and an equal amount in the form of potato, approximately 70 cc. alkali. Plantation laborers eat on an average of 50 pounds of rice per month which yields approximately 2660 calories and 70 cc. acid per day. With the remainder of the diet consisting largely of meat, fish and eggs which contain a large preponderance of acid-forming elements, its potential acidity is further increased.

The Ewa Plantation Health Project

Can the masses of rice-eating people in Hawaii today be taught to eat native foods, particularly taro and sweet potato?

The Ewa Plantation Health Project is an attempt to answer this question. A start was made in February 1930 in an isolated village of about 100 Filipino families, where the mortality of infants and pre-school children was exceptionally high, and dental decay among the Hawaiian-born, almost universal. The approach was through the baby, the mother, the expectant mother and the new baby; the pre-school and school children and adult population. An infant feeding center was opened. Enrolment of babies was voluntary with parents. The fee was $1.00 per month. It took two months to secure the first member. By the end of six months every baby in the village was enrolled, and the infant mortality rate the first year dropped from 320.5 to zero. Mortality of pre-school children also dropped to zero. The success of the undertaking prompted its extension to cover the entire plantation. The second “Health Center” was opened in June 1931; the third, in August 1931.

Chart I shows the infant deaths and principal causes for the past four calendar years.

Chart II shows the average heights and weights and the incidence of tooth decay in groups of babies twelve to fifteen months of age on different types of diets.

Table VII gives the same findings shown in Chart II, with additional data.

It is the custom of Oriental and Filipino mothers to feed their babies at the breast for fifteen months or more, often as long as two years. “Soft rice,” bread and cereal breakfast foods are usually started at about the sixth month, and by the end of the first year, the child is eating the “family” diet.

As a routine procedure, all babies enrolled in the plantation infant feeding clinics are fed poi at the age of one month.

Assuming that the average child thirteen months of age weighs approximately twenty-two pounds and requires an amount of food furnishing 1100 calories, the composition of the diets as indicated in Chart II is estimated in Table VII. 

Comment

The 850 children of all ages and all nationalities on Ewa Plantation who have learned to like taro and sweet potato and are eating them daily indicate the answer to the question “Can taro and sweet potato be reinstated in the diet in Hawaii?” We believe they can.

Charts I and II bring out striking parallelisms between mortality, physical development and dental decay in relation to diet. With the tremendous drop in mortality of infants and pre-school children since the opening of the infant feeding clinics, there has been a marked improvement in health. Pneumonia, diarrhea and enteritis and beriberi had long constituted three of the principal causes of the high infant death-rate on the plantation. There has been one death from pneumonia (associated with whooping cough) in two and one-half years; none from diarrhea and enteritis during the same period, and none from beriberi in more than eighteen months. Concomitantly there has been a marked decrease in the incidence and severity of dental decay.

Although practically 100 per cent of the plantation babies (laboring class) have teeth that are obviously defective (pitted, soft, chalky and with areas from which the enamel is sometimes entirely missing) as they erupt, it does not follow that such teeth necessarily decay. In a group of forty-two babies who were fed on cow’s milk from early infancy with supplements of poi (steamed taro root ground into a paste), sweet potato, fruit, vegetable, meat and egg according to age, only three developed odontoclasia (Chart II). All of the latter, in addition to the foods mentioned, had rice, bread and cereal breakfast foods. One had a whole egg almost daily for four months (from nine to thirteen months of age). Fig. 1.

Fig. 1–The upper anterior teeth of a Portuguese baby thirteen months of age. The incisal edges of the central incisors were obviously defective as they came through the gum and disintegrated before the teeth erupted. The lesion called odontoclasia is more advanced on the lingual surface than on the labial. The baby was artificially fed from soon after birth and received one quart of cow’s milk daily at the age of three months; thereafter, in addition to orange juice, vegetables, cereals especially prepared for infants, meat and eggs according to age. One egg daily was fed from the tenth month of age. His growth curve paralleled that of the average white child. Physical development was excellent. The enamel was mottled and chalky, and could be scraped off in regions. The two dark spots on the lingual surfaces of the central incisors are exposed dentin which has become deeply stained. Urine reaction was strongly acid (pH 5.4 to 5.8).

 

Not one of the babies who had poi and sweet potato exclusively as the carbohydrate supplement to his diet developed odontoclasia. Furthermore, the decay process was arrested in certain individuals, who, on admission to the feeding clinic, had teeth that were rapidly disintegrating. Figures 2 and 3 show two such cases.

Fig. 2–The anterior teeth of a four-year-old child who was put on a milk-poi-sweet potato vegetable diet at nine months of age. His expectancy of life was almost zero. Four upper anterior teeth were erupted and were almost completely denuded of enamel. The urine reaction was strongly acid (pH 5.0 to 6.0) at the time the diet was started and for more than two months afterward. It subsequently became normal (pH 0.2 to 7.0). The physical well-being of the child improved rapidly and the teeth hardened in texture. The roughened surfaces became smooth and glazed. No cavities have developed in the molars.

Fig. 3–Arrested odontoclasia in a five-year-old child. The crowns of the teeth are almost completely denuded of enamel. The exposed dentin has become hard and smooth.

 

In striking contrast to this group were the eleven babies who were also essentially artificially fed on cow’s milk from early infancy but whose carbohydrate supplement consisted of grain foods. Some of the latter equalled or exceeded the average white child in physical development. All had decayed teeth before the age of fifteen months, and half of their erupted teeth were involved.

Tooth decay in the breast-fed babies on the plantation is almost universal. Since a condition simulating decay has been found in the unerupted teeth of new-born infants as well as of older breast-fed babies, it is logical to assume that the fault lies in the mother, and whatever its nature, it is carried over into her milk.

Why Odontoclasia in Breast-Fed Babies?

If the fault in the mother’s milk is a deficiency of calcium or phosphorus or of vitamins A or B, or a combination of these factors, babies fed on cow’s milk which furnishes all of these elements in more than adequate amounts should not suffer tooth decay. But they do, under certain conditions (Chart II).

If the fault in the mother is due to a deficiency of calcium, phosphorus or vitamin B, or to a combination of the three resulting from a diet containing a large excess of polished rice, the substitution of oats for the rice–the former contains more than seven times as much calcium, more than four times as much phosphorus as the latter, and is a good source of vitamin B–should correct these faults and produce sound teeth in the babies, but such is not the case. The teeth of two breast-fed Filipino babies whose mothers ate rolled oats in place of rice during pregnancy and lactation were ravaged by decay before they were completely erupted. The mothers of both babies (and probably the fathers also) had perfect teeth as far as freedom from decay is concerned. They had lived in Hawaii a short time and were members of a religious cult which forbade the use of animal or cooked foods. Rolled oats, which had previously been steamed for twelve hours or more and were bought in packages, were considered “raw,” and were adopted by the organization as their principal carbohydrate food. Raw peanuts supplied the greater part of the protein of their diet. They did not use sugar except in the form of cane, which the older children and adults sometimes chewed.

If vitamin-B deficiency were the cause of tooth decay in Hawaii, it would be expected that adults who suffer from beriberi would also have caries, yet many do not. Conversely, the addition of vitamin B in generous amounts to the diet should prevent and cure odontoclasia in babies, but it does not. Compressed yeast, one of the richest sources of vitamin B, has been fed to Filipino babies on the plantation as a routine procedure for more than three years as a preventive of beriberi. In addition, formulas were prepared with a water extract of rice polishings for more than a year. These measures probably saved lives but had no apparent effect upon the incidence of tooth decay. Figure 4 is a photograph of the left half of the upper dental arch of a Filipino baby who died of complications following measles. He was fifteen months of age and had been breast-fed from birth. He was given also daily a suspension of compressed yeast in water for twelve months, the amount being increased gradually from one-fourth of a cake (Fleischmann’s) at three months of age to one whole cake at nine months and thereafter. The enamel of the upper central and lateral incisors and occlusal surfaces of all of the first molars were almost completely disintegrated.

Fig. 4A and 4B–Upper left dental arch, dissected postmortem, from a Filipino baby of fifteen months, who died of complications following measles. The baby was breast-fed from birth. Irradiated yeast was given at three months of age, and was continued until the time of death. Note the condition of the enamel on labial and lingual surfaces of the incisors and occlusal surface of the molar.

 

If a deficiency of vitamin C were the underlying cause of dental decay, the prevalence and degree of odontoclasia in the teeth of babies of Hawaii would warrant the assumption that scurvy is also endemic and the principal cause of death. On the contrary, we have never known of a case of scurvy in an adult or in a breast-fed baby. Fresh orange juice and vegetables in amounts usually given babies do not prevent or arrest tooth decay in either breast-fed or artificially fed infants whose carbohydrate supplement consists of grain foods.

Fig. 5–Teeth (anatomical specimen) of Hawaiian baby eighteen months of age. Only a rim of enamel remains at the gingival line on the central and lateral incisors. The enamel on all surfaces of all teeth erupted (fourteen) is partially disintegrated and so soft that it can be easily scraped away.

 

If vitamin D is the prime factor in the formation and preservation of the teeth, as is generally thought, why should dental decay be so wide-spread and so rampant in Hawaii? Honolulu enjoys seven and one-half hours of tropical sunshine daily. Vitamin D, furthermore, in the form of cod-liver oil, egg and irradiated yeast, has failed to prevent or arrest tooth decay under conditions as they exist today.

If, also, as has been recently claimed,⁵ a diet rich in vitamin D and phosphorus insures freedom from dental caries, how can the high incidence of tooth decay in Hawaii be explained? A meat, fish, egg and grain diet as is generally employed is rich in phosphorus. The tropical sunshine furnishes vitamin D in abundance.

Fig. 6–Unerupted upper cuspid and molars which were dissected postmortem from the jaws of a ten-month-old baby who died of beriberi. All surfaces, including the tips of cusps of molars, appeared to be in a state of active dissolution.

 

Egg in Relation to Dental Decay in Hawaii

The per capita consumption of eggs in Hawaii, as shown in Table VI, was eleven per month in 1932. Most of the families in the rural districts raise chickens for home use, and the consumption of eggs by the children is relatively high compared with that by the city children. The incidence of odontoclasia in plantation children is also relatively high.

Five cases of odontoclasia and caries have been observed in individuals who ate unusual amounts of egg. One of these was an adult who had always been immune to decay. Tuberculosis developed, and he adopted a diet consisting essentially of milk, cereals and nine raw eggs a day. The enamel of the teeth soon began to soften and disintegrate, and within a year every tooth was reduced to a stump. Another striking case was a young pregnant woman who could tolerate little besides raw egg. A normal appearing, healthy baby was born and was breastfed. The mother continued to eat eggs in quantity during lactation. She suffered active caries and the baby developed odontoclasia to a marked extent.

Taro and Sweet Potato versus Grains in the Tropics

Taro and sweet potato (root and tuber, respectively) are indigenous in the tropics. They constituted the principal carbohydrate foods of the Hawaiians for hundreds of years. The culture of these foods was their principal industry. Grains are indigenous in the temperate zones. Their culture in Hawaii is too expensive to be profitable. With the influx of foreigners, grains have gradually replaced taro and potato in the diet of the people, and Hawaii has changed from a country that was entirely self-supporting to one that is almost wholly dependent upon others for sustenance. Concomitant with the change in diet the people have suffered physical deterioration. Susceptibility to respiratory diseases is high. Dental decay is endemic. These facts indicate that types of diets must be suited to climates, and that roots and tubers have a very special significance in the tropics.

Acid-Base Balance of the Diet in Relation to Dental Decay in Hawaii

To what may rampant tooth decay be attributed in a child whose diet contains one quart of cow’s milk, an egg, fresh fruit, vegetables and meat daily, in addition to cereals and other foods? As far as protein, calcium, phosphorus and vitamins are concerned, the adequacy of such a diet cannot be questioned. Perhaps there is some undiscovered factor which is specific for dental decay which is lacking or insufficient in amounts in the foods mentioned. Our explanation is that the fault is in the child rather than the food; that he probably has an “acidotic constitution,” and his alkali requirements are not met by that type of diet. A number of such cases have come under our observation, and invariably, when grain foods have been omitted from the diet and taro and sweet potato used in generous amounts, the decay process has been arrested. We are unable to offer any explanation, other than their high degree of potential alkalinity, for the fact that taro and sweet potato, though rich in carbohydrate and relatively poor in calcium, phosphorus and vitamins, are effective in preventing dental decay with or without the addition of milk.

 

Fig. 7A

Fig. 7B

A and B are photographs of the teeth of brother and sister, three years and twenty-two months of age, respectively. The boy, artificially fed from birth with poi and sweet potato as his principal carbohydrate foods, had excellent teeth with no odontoclasia. Enamel defects which were obvious at the time of eruption of the teeth were eventually obliterated. The girl, breast-fed from birth with rice and bread as the principal carbohydrate foods of her diet, had rampant odontoclasia which involved every one of her fourteen erupted teeth at eighteen months of age. The substitution, at that time, of poi and sweet potato for the greater part of the rice and bread of her diet was accompanied by obvious hardening of the teeth and arrest of the decay process during the next four months.

 

If we assume that a year-old baby is taking not less than twenty-four ounces of milk daily, about 350 calories in the form of bread and cereals and small amounts of fruit, vegetable, meat and egg, the potential alkalinity of his diet will range from 6 to 10 cc. normal solution. If the grain foods are replaced with taro and potato, the potential alkalinity of the diet will be increased to 36 to 45 cc. The potential reaction of the diet of a breast-fed baby on a rice-bread-breakfast cereal supplement is practically neutral. In terms of pounds of body weight, a diet which includes a quart of cow’s milk a day and furnishes fifty calories and an excess of 2 cc. of normal alkali per pound is regarded by us as optimal for the child of from twelve to fifteen months in Hawaii. In our experience it has been invariably associated with excellent physical development, high resistance to disease of all kinds and freedom from tooth decay. Such a diet is employed at the plantation infant-feeding clinics, the carbohydrate supplement being in the form of poi (steamed taro root made into a paste) and potato. A diet, similarly constituted as far as milk, vegetables, meat and eggs are concerned, but containing rice and bread as the principal carbohydrate foods, yields as many calories and almost as much calcium, phosphorus and vitamins, but the alkali excess is reduced to 0.6 cc. per pound of body weight. It is estimated that in the old days adult Hawaiians had an excess of alkali in their diet of not less than 1.0 cc. per pound. The diet of plantation laborers and their wives today probably contains as much as 0.5 cc. excess acid.

 

Blood and Urine Findings in Supposedly Normal Individuals in Hawaii

The alkali reserve (CO2 combining power) of the blood plasma of supposedly normal adults in Hawaii was found to be low (50 to 60 vols. per cent) in all of the forty cases examined. The urine reaction of those who eat diets high in potential acidity is, as a rule, strongly acid (pH 5.0 to 6.0), as is also the urine of breast-fed babies of mothers who eat acid residue foods in excess.

The urine reactions of four babies were determined almost daily during periods of months. The pH of the urine of all varied between 5.0 and 6.0 for more than two months after they were put on a cow’s milk formula. The addition of poi, sweet potato, orange juice and vegetables in increasing amounts was effective, eventually, in bringing the urine reaction within the normal range (pH 6.2 to 7.0). The physical condition of the babies improved; obviously defective teeth hardened and have remained intact to date (one to three years).

Disintegration of Enamel in Unerupted Teeth

To what may disintegration of enamel of unerupted teeth in infants of all ages, even in the newly born, be attributed? In every case observed it has been associated with an imbalance in the systemic complex toward the acid side–starvation in two cases; nephritis in the mother; and maternal diets which have habitually contained a large preponderance of acid forming elements.

Alkali Requirements of the Diet Under Different Conditions

There is a clear-cut relationship in Hawaii between the incidence of dental decay and types of diet. Diets which contain a certain preponderance of alkaline elements (roots, tubers, fruits and. vegetables) have been found to be invariably associated with freedom from or arrested decay, regardless of whether the carbohydrate, calcium, phosphorus and vitamin contents are high or low, or any known combination of these factors. It apparently matters not whether the consistency of the diet is hard or soft; whether the occlusion is good or bad; whether the teeth are crowded or well spaced; whether oral hygiene is practised or not; whether the tooth structure is hypoplastic or faultless, or whether there is even any enamel present. We have never known of a case of active caries in a normal individual (adult) who obtains from 60 to 70 per cent of the calories of his diet from poi and sweet potatoes.

Studies reported from various parts of the world indicate that alkali requirements vary under different conditions. Some of these are mentioned below.

Age. It has long been recognized that infants, compared with adults, have “acidotic constitutions.” Because the baby is growing rapidly and is active, he produces acid products at a relatively high rate. His reserve of alkali in his blood and tissues is relatively low. It is reasonable to assume that he needs more alkali per one hundred calories of food or pound of body weight than does the adult. This was found to be the case in the diets cited above regarded as optimal (2 cc. N. solution per pound for the infant and 1.25 cc. for the adult).

Vitamin D. There is evidence indicating that vitamin D tends to decrease the alkalinity of the body fluids. If this is true, the more vitamin D, the higher the alkali excess should be, and vice versa, if a normal “body balance” is to be maintained. According to this, babies in the temperate zone who are fed on cow’s milk should have more sunshine or cod-liver oil (vitamin D) than the breast-fed, because cow’s milk is relatively high in potential alkalinity compared with woman’s. In the tropics, where there is a superabundance of vitamin D in the sunshine, more alkali is required. In the arctics and those regions where it is habitually cold, man thrives best on flesh foods which yield an excess of acid elements.

Disease. Many disease processes are associated with high acid production and low alkali reserve in the blood. Diabetes and nephritis are outstanding in this respect. Both are associated with a high incidence of tooth decay, which, as has been shown,5 may be arrested by the ingestion of a diet which is high in potential alkalinity (fruits and vegetables).

Development. The incidence of tooth decay rises to a peak at the age of puberty. It is said to be increased during pregnancy. The need for alkali excess at such times appears to be relatively great.

Climate. Analyses of diets of primitive peoples furnish convincing evidence that there is no one diet suited to the human race the world over. Modern methods of marketing, preserving and transportation have tended to make a universal diet. Primitive man subsisted on foods that were indigenous in his particular locality, and varied his diet with the season. Physical deterioration of the people has followed in the wake of imported foods, particularly the importation of grains to the arctics and tropics. As a source of carbohydrate in the diet, grain foods are not interchangeable with roots and tubers. The latter, when burned in the human body, yield an excess of alkaline elements, which apparently is needed to balance the physiologic effect of a warm climate. The colder the climate, the less the need for alkali residue foods (fruits and vegetables), and the more important those that yield an acid ash (meat, eggs and grains), until man reaches the lands of habitual snow, where flesh foods seem best suited to man’s needs.

The Role of Bacteria in Dental Decay

The role of bacteria in relation to dental decay in Hawaii has not been investigated. Whether those foods which yield an alkaline ash inhibit the growth of acid-producing organisms or neutralize their products, or both, we do not know. Solution of enamel may occur in extreme cases of acidosis, in the unerupted teeth of infants. This emphasizes the systemic factor. We do know that the channels through the enamel of the teeth of babies and preschool children in Hawaii are very large; that the tooth surface in the majority of cases is extremely rough and porous; that the teeth are universally encrusted with food debris; that if the carbohydrate of the diet consists of rice, bread and other grain foods, the teeth disintegrate quickly; that if the carbohydrate is in the form of poi and sweet potato, markedly defective teeth do not decay and eventually become hard and smooth. The evidence that tooth decay can be controlled by diet is overwhelming. We regard the role of bacteria as relatively unimportant, since their effect upon the teeth may be controlled by diet.

Summary

Dental decay is endemic in Hawaii and is exceedingly rampant in form in breast-fed infants and pre-school children of the laboring population. Blood-vessel diseases, pneumonia (broncho- and lobar) and tuberculosis rate first, second and third, respectively, as causes of death in the Territory. The “common cold” is almost universal among the children. The per capita consumption of grain foods (exclusive of prepared foods) for the Territory was twenty-seven pounds per month in 1932. Plantation laborers eat fifty pounds per man per month.

Many diseases prevalent in Hawaii today were unknown before the arrival of the white man in 1778. The people were famed for their splendid physiques and beautiful teeth. It is estimated that not less than 60 per cent and probably as high as 75 per cent of the calories of the diet came from carbohydrate foods–taro and sweet potato, principally. Grain foods and cow’s milk were unknown. The reninant of Polynesians living today who cling to their ancient food customs still have “splendid physiques and beautiful teeth” and are far superior in these respects to their city cousins or any national group residing in the Territory.

Diets rich in calcium, phosphorus and vitamins (twenty-four to forty ounces of cow’s milk, daily for nine months or more, with fruit, vegetable, egg and meat according to age) did not prevent or arrest odontoclasia in eleven babies twelve to fifteen months of age (100 per cent of the group) when the potential alkalinity of the diet was low–six to ten cc. normal solution. Such a reaction is obtained when 30 to 40 per cent of the calories of the diet are in the form of grain foods. Diets similarly constituted, but high in potential alkalinity (excess alkali equivalent to 36 to 45 cc. N. solution, per day) were effective in preventing odontoclasia in thirty-nine of the forty-two babies so fed. Such a reaction results when roots and tubers (poi and sweet potato) are used as the carbohydrate supplement instead of grain foods.

The alkali reserve (CO2 combining power) of the blood plasma of supposedly normal adults in Hawaii is low (50 to 60 volumes per cent). The urine acidity of individuals of all ages (including that of breast-fed babies), whose principal carbohydrate foods are rice and bread, is high (pH 5.0 to 6.0). These facts, combined with the high incidence of certain diseases and dental decay in the newly erupted teeth of infants, suggest an imbalance in the systemic complex toward the acid side which may have resulted from the combined effect of a tropical climate and the long-continued use of a diet which contains inorganic acid elements in great excess.

The tremendous reduction in infant mortality (from a rate of 160.7 in 1929 to 25.4 in 1932), improved well-being, reduction in the incidence of pneumonia, diarrhea and enteritis and beriberi, and marked improvement in the dental condition of the plantation babies which have accompanied the reduction of rice and bread in the diet (complete elimination in some cases) and inclusion of equivalent amounts of poi and sweet potato, suggest that tooth decay and certain systemic diseases may be related to one another through a common metabolic fault–an imbalance toward the acid side in blood and tissues.

Regardless of the mechanism of tooth decay or mode of action of foods on the body or in the mouth, the analyses of facts past and, present in Hawaii convince us that when taro and sweet potato are reinstated to their former place in the diet of the people, tooth decay and its attendant ills will become as rare as they used to be, and that many of Hawaii’s health, dental, social and economic problems of today will automatically be solved.

There appears to be a relationship between alkali requirement and age, vitamin D, climate and disease, assuming that the diet is otherwise well constituted. These relationships are discussed.

 

Editor’s note: Since the era in which this article was written, society’s understanding of respectful terminology when referring to ethnic and cultural groups has evolved, and some readers may be offended by references to “primitive” people and other out-of-date terminology. However, this article has been archived as a historical document, and so we have chosen to use Jones’ exact words in the interest of authenticity.  No disrespect to any cultural or ethnic group is intended.

 

References Cited:

1. Jones, M. R., N. P. Larsen, and G. P. Pritchard: “Dental. Disease in Hawaii.” Dental Cosmos, 72:439-450, 574-577, May and June 1930.
2. Ibid.: Amer. Journ. Dis. Child., 45:789- 798, April 1933.
3. Ibid.: Journ. A. M. A., 99:1849-1852, November 26, 1932.
4. Jones, M. R.: Journ. Dental Research, 10:281-312, June 1930.
5. Boyd, J. D., and C. L. Drain: Journ. A. M. A., 90:1867, 1928.
6. Agnew, Mary C., R. Gordon Agnew, and Frederick F. Tisdall: Journ.. A. D. A., 20:193-212, February 1933.