Before fluoride was added to drinking water in some Western countries, it was considered a toxic substance. Scientists had concerns that high levels of fluoride in the diet would lead to toxicity symptoms, the first of which was a mottling of the teeth usually in children (fluorosis). For example back in 1941, one group of researchers stated in a paper published in the Journal of Nutrition1 that ‘there is a definite fluoride hazard in the United States and throughout the world. The occurrence of fluorine in drinking water is general and in many communities, especially those served by deep wells, the concentration is such as to cause mottled enamel in children during periods of tooth formation’. In the intervening period, big business has convinced bureaucratic governments to add hexafluorsilicic acid to drinking water, with disastrous health consequences.
The concern regarding fluoride toxicity had lead researchers to assess methods of decreasing fluoride accumulation in the skeleton. To test the effects of calcium on fluoride accumulation, researchers fed rats either a high or low calcium diet and then measured the fluoride accumulation in their skeletons1. The researchers found that increasing the calcium in the diet from 0.23 to 0.73 % decreased the amount of fluoride accumulation by between 10 and 13 % and also increased the weight of the skeleton. Magnesium is known to inhibit fluoride absorption by formation of soluble complexes in the gut2, suggesting that high magnesium diets can decrease fluoride accumulation. It appears that calcium is also able to inhibit accumulation of fluoride in the skeleton but by a different mechanism. High calcium and magnesium diets might therefore protect from fluoride toxicity in a synergistic way.
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1Lawrenz, M. and Mitchell, H. H. 1941. The effects of dietary calcium and phosphorus on the assimilation of dietary fluorine. Journal of Nutrition. 22: 92-101
2Cerklewski, F. L. 1987. Influence of dietary magnesium on fluoride bioavailability in the rat. American Journal of Clinical Nutrition. 117: 496-500
