Mouth Microbes – Diet and Dentists

Last Updated on November 27, 2019 by Afifah Hamilton
Read Time: 2 min

In our recent talk on the effect of cereal grains in the diet we discussed the emergence of caries at the dawn of agriculture and presented some experimental evidence from the 1920’s carried out by Drs Edward and May Mellanby which showed that removing grains, and especially oats, from the diet reversed tooth decay – i.e. cavities actually healed. What lead them to this experiment is fascinating in itself. It was observed that diabetic children had better teeth and this was attributed to their ‘diabetic diet’ – a diet which, in those (more enlightened?) days, was a low grain (i.e. low carb) diet! Their explanation was that correct tooth remineralisation was inhibited by the grains, which, they postulated, interfered with vitamin D and with dietary calcium and phosphorous metabolism, thus disabling the proper effects of these nutrients in the teeth, and possibly other areas of the skeleton. I was subsequently very pleased to read this great article over on the National Geographic blog entitled:

Prehistoric Plaque and the Gentrification of Europe’s Mouth

The author Ed Yong reports on a series of experiments carried out in the last few years where scientists have studied the oral microbes preserved in plaque on the teeth of archaeological skulls. What they found is a marked change in the microflora that could explain the observed caries explosion commensurate with a switch to grain cultivation 6000 years ago in Europe. The introduction of carbohydrates into the diet provided a new source of food for oral bacteria leading to a change in the micro-flora. The increase in acid forming bacteria paralleled the increase in caries. The conclusion, clearly, is that eating a low-carb, grain free diet, similar to that of our paleolithic ancestors should help restore the correct bacterial balance and protect our pearly smiles perfectly naturally.

The changes that have happened in our oral micro-biome over the millenia is but one example of the much broader topic of gastrointestinal dysbiosis which we focused on in our talk on fermented foods. During that talk we pointed out how antibiotics can lead to dysbiosis as they kill off both the good and bad bacteria creating an ecological niche for the baddies to recolonise, with all the consequent disease that can follow. In his article Ed Yong suggests something similar, arguing that the use of mouthwashes is counter productive, preventing a healthy mix of bacteria from establishing that might protect our teeth.

One area that still needs clarification is a fascinating observation of the Mellanbys: that the reversal of dental caries was observed by reducing grains alone, not carbohydrates generally or sugar specifically! Here is their advice:

…the amount of cereal eaten should be reduced, particularly during infancy and in the earlier years of life, and should be replaced by an increased consumption of milk, eggs, butter, potatoes, and other vegetables. They also indicate that a sufficiency of vitamin D and calcium should be given from birth, and before birth, by supplying a suitable diet to the pregnant mother.

So there you have it: Give your teeth a chance. Drop the grain. Get out in the midday sun. Avoid the mouthwash. Eat like a caveman and look forward to fewer trips to the dentist!

Additional Resources
Click here to download the original 1932 BMJ paper by Mellanby and Pattison:
Cereal-Free_Diet_and_Dental_Caries (pdf)

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