FLUORIDE BIOAVAILABILITY - NUTRITIONAL AND CLINICAL ASPECTS

Dietary fluoride obtained from food and water is efficiently absorbed from both the stomach and small intestine without regulation. A variet y of dietary factors have been identified that either decrease or incr ease fluoride absorption and utilization. About half of absorbed fluor ide is quickly taken-up by developing bone and teeth, and the remainde r is excreted in the urine. The amount of fluoride excreted in the uri ne increases as bone growth slows. Nearly all of total body fluoride, which is second among the trace elements only to iron, is found in-the skeleton. Although fluoride's unique role in mineralization provides the basis for its recognition as a beneficial trace element for dental health of humans, a more subtle role of fluoride in the mineralizatio n of bone is also likely to exist. As with other essential trace eleme nts, fluoride's action is biphasic in nature in that toxicity (fluoros is) can occur. Therapeutic effects of fluoride in the treatment of ost eoporosis continue to be studied, and recent developments in this area point to a mitogenic role of fluoride in osteoblast cell proliferatio n. Recognition of fluoride essentiality for human health, rather than just being classified as beneficial, is likely to be forthcoming espec ially if reduction of a chronic disease is added to the criteria that establish a recommended dietary allowance. (C) 1997 Elsevier Science I nc.