Silicon Content of Italian Mineral Waters and Its Contribution to Daily Intake

Abstract

ABSTRACTDietary intake is the main source of silicon for humans. The essentiality of silicon for man has not been clearly established, and no suitable data are available for the establishment of a tolerable upper intake level. Recently, a few cases of silica stones in subjects not ingesting trisilicate antacid have been reported, as well as 1 case of renal silica calculi in a 10‐mo‐old boy, ascribed to the silicate‐rich mineral water used to dilute milk. The purpose of this study was to collect extensive data on the silicon content of mineral water that could be combined with data on different foods to study the overall intake of silicon in the diet and to evaluate the potential risk associated with a high intake of this element. Results relating to 207 brands of mineral water show a low silicon concentration (<10 mg/L) in 77% of samples, with the highest levels (>25 mg/L) occurring primarily in water from volcanic areas. The contribution of mineral water to the total consumption of silicon was calculated, considering both the average intake of water by the Italian population and the recommended intake. When the estimated daily intake with solid foods and other beverages was added, the intake was in the range of 45 to 69 mg/d for a consumption of 700 mL of water and 48 to 99 mg/d for a consumption of 1500 mL of water. These values are near or above the upper limit of the typical dietary intake of 20 to 50 mg silicon/d, which is regarded as unlikely to cause adverse effects. The assumption of silicon by newborns deserves particular attention, in view of their special sensitivity and of a reported case of urinary silica calculi in an infant. The levels of silicon we found never reached the value found in the case described.