Fluoride concentration in foods from Iran.

Knowledge of fluoride intake is important in optimizing the caries-preventive role of fluoride, and the measurement of fluoride intake usually requires information on the fluoride concentration in foods and drinks. Most information comes from developed countries and there are no data on fluoride concentration in foods in Middle Eastern countries including Iran. The aim of the study was to: (a) describe a modification to the silicon-facilitated diffusion method for determining fluoride concentration, (b) provide information on fluoride content of foods in Iran to supplement food tables for the Middle East, and (c) determine the effect of variation in the fluoride concentration of drinking water on the fluoride concentration of prepared foods. Five hundred and ten samples of 84 popular foods and drinks were collected from three areas of Iran where water fluoride concentrations were 0.32, 0.58 and 4.05 mg/L. The mean recovery of fluoride added to food samples before diffusion was 98 +/- 5%. Values for duplicate analysis of 20 food samples were within 0.03 microgram F/g. Most of the samples of foods and drinks came from the area with 0.32 mg F/L in water supplies. For 30 of the 84 items, fluoride concentration was below 0.1 microgram/g. Fluoride concentrations in the cereals group (which constituted much of the diet) were mainly between 0.2 and 0.3 microgram/g, when prepared for consumption. It was concluded that: (a) modification of a published method for determining fluoride concentration of foods appeared to be an advance, (b) values for fluoride concentration of foods commonly consumed in Iran showed variation between groups but were in broad agreement with published data, and (c) concentration of fluoride in water influences positively fluoride concentration in foods cooked in water, but the increase in foods was less than the increase in fluoride concentration in water.