Fluoride intake and cortical and trabecular bone characteristics in adolescents at age 17: A prospective cohort study

To investigate the associations between period-specific and cumulative fluoride (F) intakes from birth to age 17 years, and radial and tibial bone measures obtained using peripheral quantitative computed tomography (pQCT).

Participants (n = 380) were recruited from hospitals at birth and continued their participation in the ongoing Iowa Fluoride Study/Iowa Bone Development Study until age 17. Fluoride intakes from water, other beverages, selected foods, dietary fluoride supplements and dentifrice were determined every 1.5-6 months using detailed questionnaires. Associations between F intake and bone measures (cortical and trabecular bone mineral content [BMC], density and strength) were determined in bivariate and multivariable analyses adjusted for height, weight, maturity offset, physical activity, and daily calcium and protein intake using robust regression analysis.

Fluoride intake ranged from 0.7 to 0.8 mg F/d for females and from 0.7 to 0.9 mg F/d for males. Spearman correlations between daily F intake and pQCT bone measures were weak. For females, Spearman correlations ranged from r = -.08 to .21, and for males, they ranged from r = -.03 to .30. In sex-specific, height-, weight- and maturity offset- partially adjusted regression analyses, associations between females' fluoride intake and bone characteristics were almost all negative; associations for males were mostly positive. In the fully adjusted models, which also included physical activity, and protein and calcium intakes, no significant associations were detected for females; significant positive associations were detected between F intake from 14 to 17 years and tibial cortical bone content (β = 21.40, P < .01) and torsion strength (β = 175.06, P < .01) for males.

In this cohort of 17-year-old adolescents, mostly living in optimally fluoridated areas, lifelong F intake from combined sources was weakly associated with bone pQCT measures.