Urinary fluoride excretion in 6- to 7-year-olds ingesting milk containing 0.5 or 0.9 mg fluoride

Effectiveness of 0.5 mg fluoride (F) milk ingestion in preventing caries has been termed only 'moderate'. In this 3-arm partial cross-over intervention, 32 children aged 6-7 years in a non-F area were recruited and urinary F excretion (UFE) measured before and after ingestion of 0.5 or 0.9 mg F milk. Maintaining customary dietary and oral hygiene habits, children underwent a 2-week 'wash-in' with non-F milk, providing a 24-hour urine sample on day 4 of non-F (baseline) and F milk ingestion containing either (i) 0.5 mg or (ii) 0.9 mg F (intervention). A comparative group of thirteen 6- to 7-year-olds living in fluoridated areas provided a 24-hour urine sample on day 4 of daily non-F milk ingestion, following a 2-week non-F milk wash-in. Valid urine samples were analysed for F and UFE estimated from corrected 24-hour urine volume and F concentration. For the 24 test children providing 2 valid urine samples, mean (95% CI) change in corrected 24-hour UFE was 0.130 (0.049, 0.211) and 0.153 (0.062, 0.245) mg/day for 0.5 mg (p < 0.007) and 0.9 mg F (p < 0.001) groups, respectively. Post-intervention, mean (SD) corrected 24-hour UFE was 0.437 (0.153) mg/day and 0.420 (0.188) mg/day for the 0.5 and 0.9 mg F groups, respectively, which were lower than the WHO provisional standards (0.48-0.60 mg F/day). F milk consumption significantly increased UFE; however, the F content of 0.5 and 0.9 mg F milk may be too low to achieve WHO provisional UFE standards concomitant with optimal F exposure in children aged ≥6 years.