In New Zealand the soil is generally deficient in calcium, phosphorus, iron and iodine. High calcium-intake in the diet does not prevent caries ; low phosphorus-intake diminishes resistance thereto. Low dietary intake of iron favors onset of caries ; high intake of iron appears to compensate for deficiency in calcium or phosphorus. High dietary intake of iodine raises, low intake diminishes, resistance to caries.
The extent of excess of basic over acidic metabolic end-products of the diet is unimportant in relation to caries. There is no relation between content of vitamin in the diet and incidence of caries. A small supply of vitamin D, and oatmeal and other cereals in quantity, may be associated with high degree of immunity to caries. Quantity of milk consumed and incidence of caries are unrelated. A regulating diet raises, and a constipating diet lowers, resistance to caries. In New Zealand there is an excessive consumption of sugar and confectionery in forms that favor caries. In children susceptible to caries, saliva is low in specific gravity, very viscous, and slow in flow. In an investigation to determine the relationship, if any, between incidence of caries and goitre, evidence was contradictory. The results, considered as a whole, suggest that factors responsible for medium or large goitres in children favor onset of caries. No dental significance appears to be attached to the presence of incipient or slight goitre.
Reference: New Z. Den. J., 1932, 1935.