Taro and Sweet Potato

If the carbohydrate in the diet consisted of rice, bread and grain food, the teeth decayed and disintegrated quickly.  If the carbohydrate was in the form of poi and sweet potato, defective teeth do not decay and eventually become hard and smooth.  We regard the role of bacteria as relatively unimportant, since their effect upon teeth may be controlled by diet.

Dr Martha R. Jones

Captain Cook landed in Hawaii in 1778.  He found people who were tall, brown skinned with great muscular strength and broad dental arches.  Dental decay was rare or unknown.  The principal food crops were taro, usually consumed as poi,  and sweet potato, which together made up 60 to 75% of the diet.   Coconuts, fruit, fish and shellfish made up most of the remainder.  Milk and grain foods were unknown.

Fast forward to the 1920’s.  Rice, bread and other grain products had largely replaced taro and sweet potatoes as the staple.  Early childhood caries (ECC) were rampant amongst the breast-fed children of plantation labourers.   Tooth decay was so aggressive that it was frequently necessary for infants to have teeth removed before they reached their first birthday.  By 2 years, almost 100% of those children were affected.  Almost all of the plantation babies had pitted, soft chalky teeth from which the enamel was sometimes completely absent.  The decay progressed in broad lines across the teeth, rather than in pits and fissures, and was associated with growth “spurts”.  Active children who played outside in the sun were more susceptible.  Rampant decay rarely occurred in those who did not eat grains, but instead consumed the traditional taro and sweet potatoes.

The children appear to have been grossly deficient in calcifying minerals, especially calcium, and possibly phosphorus and magnesium.  A study was undertaken whereby 11 babies were provided diets rich in calcium, phosphorus and vitamins with supplementation by a quart of cow’s milk per day for nine months, together with fruit vegetable, egg and meats.   When consumed with a diet where 30 to 40% of the calories came from grains, this supplementation did not prevent the rampant decay.  However, when taro and sweet potatoes were substituted for the grains in the diet, rampant caries was prevented in 39 out of the 42 (or 93%) of the infants.

It apparently matters not whether the teeth are crooked or well spaced; whether the oral hygiene is practiced or not; whether the tooth structure is hypoplastic or perfect, or whether there is even any enamel present.  We have never known a case of active caries in a normal adult who obtains 60 to 70% of the calories of his diet from poi and sweet potatoes.

Jones, M.R., and others, 1934: Taro and sweet potatoes versus grain foods in relation to health and decay in Hawaii”, The Dental Cosmos, 74, 395-409. [Link]

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7 Responses to Taro and Sweet Potato

  1. Pingback: Is white bread better for teeth than wholewheat? |

  2. Emily says:

    I read through the article you linked to and am confused about the conclusion and how this might affect someone, say, living in the Midwest USA. Essentially the author seemed to conclude that depending on your ancestry and/ or your climate, you might be protected from carries if eating a low grain diet that is high in starch from roots, but only if living in the tropics, and might do well on a diet that includes grains but is low in overall carbs and higher in meat? do you think any of this is still relevant? Living in america, many of us are of mixed nationalities so how do we ever really know what the best diet to prevent carries might be, according to some of the research you’ve presented.

    • Emily

      I’m not convinced that nationality, ancestry or climate are necessarily factors at all. The Inuit (Eskimoes) had spectacular teeth on their traditional diet low in carbohydrates. Boyd and Drain documented reversal and healing of tooth decay in diabetic children following a dairy-rich, almost Atkins-style diet. The Hawaiians developed perfect teeth while consuming a traditional diet largely consisting of carbohydrates. May Mellanby’s diet was stodgy British fare that quite unremarkable. This tells me that there is a wide range of diets that are capable of supporting perfect dental health. The common factors appear to be a diet rich in minerals (calcium, phosphorus and others), vitamin D from sunshine, food, and/or supplements, low in phytate (relative to the mineral intake), and limited sugar (especially sucrose) intake. Dr Price’s work also points to vitamin K2 as an important co-factor.


  3. Emily says:

    Also, one more thing I read in your above referenced article is that the researchers in Hawaii found that the more sunshine and or vitamin d given, while in the context of a grain eating diet, the worse the teeth were. The author states that essentially the body can handle more acidifying foods like grains and meat if the person has lower vit d. Is there any current research supporting this that you are aware of?

    • The article is a fascinating read. Dr Jones and colleagues proposed that it was an acidic diet at the heart of the rampant tooth decay and poor health of the Hawaiian plantation laborers. I have not been persuaded by the acidic/alkaline diet argument, although it certainly has its proponents.

      No, I am not aware of any research between acidifying foods and vitamin D intake. There is research to showing that anti-nutrient effects of phytate can be countered by modest meat consumption.

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