Fluoride and Infant Formula
Human milk is an ideal food for all infants, with rare exceptions, thus the American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for at least about 6 months and continuation of breastfeeding, as complementary foods are introduced, for 1 year or longer as mutually desired by mother and infant.1 About 21% of mothers in the US, however, never breastfeed their newborn, and breastfeeding rates at 6 months and 12 months are 49% and 27% in 2011, respectively.2 Infant formula is therefore an alternative food for many US children during early childhood.
Fluoride concentration in human breast milk, reportedly at about 0.02 ppm, is lower than in commercially available infant formulas owing to the pH gradient between milk and the interstitial fluid.3,4 The analysis conducted by Siew and colleagues found that commercially available infant formula in a typical US city had various fluoride levels and an average of 0.12 ppm (SD=0.08) in milk-based powdered concentrate while liquid concentrate and ready-to-feed milk-based formula had mean 0.27 ppm (SD=0.18) and 0.15 ppm (SD=0.06) fluoride concentration, respectively.5 Soy-based formula generally had a fluoride content higher than that of milk-based formulas but the difference was statistically significant only for the liquid concentrate formulas (0.27 vs. 0.50).5 While infant formulas themselves (regardless of types and forms) do not contain fluoride at levels that would exceed the upper tolerable limit (0.1 mg/kg/day or 0.7 mg/day for infants 0-6 months and 0.9 mg/day for infants 7-12 months) established by the Institute of Medicine,6 some infants, especially those who are exclusively fed with infant formulas reconstituted with water containing greater fluoride (i.e. >0.5 ppm) or exposed to multiple sources of dietary fluoride, will likely exceed this limit thus may be at increased risk of developing enamel fluorosis.4,5,7 According to the longitudinal investigation of dietary and non-dietary fluoride exposures to dental fluorosis and dental caries in Iowa, many children are introduced to water-added non-dairy beverages as early as 3 months of age and fluoride dentifrice during early childhood that also contribute to overall fluoride exposures and risk for enamel fluorosis.7
Scientific evidence regarding the association between infant formula and enamel fluorosis is limited and weak due, in part, to inconsistent measurement of exposures between studies, i.e. unreported differences in the amount, duration and frequency of infant formula use; unreported differences in fluoride levels of infant formulas; and variability in other sources of fluoride intake.4,8 On the basis of available evidence, the expert panel convened by the American Dental Association (ADA) Council on Scientific Affairs concluded the following:8
- The consumption of infant formula may be associated with an increased risk of developing enamel fluorosis in the permanent dentition,
- The estimated risk of enamel fluorosis related to fluoride intake from reconstituted infant formula is associated with the fluoride concentration in the drinking water,
- Factors such as multiple and often concurrent exposures to fluoride during the period of tooth development in children make it difficult to isolate an individual child’s risk of fluorosis development associated with fluoride intake from one specific exposure, such as the use of reconstituted infant formula during the first year of life.
Recommendations of the ADA expert panel on the practice of infant formula use with respect to fluoride intake (2011)8 are as follows:
- Advocate exclusive breastfeeding until the child is aged 6 months and continued breastfeeding until the child is at least 12 months of age, unless specifically contraindicated.
- For parents and caregivers of infants who consume powdered or liquid concentrate infant formula as the main source of nutrition,
- Suggest the continued use of powdered or liquid concentrate infant formulas reconstituted with optimally fluoridated drinking water while being cognizant of the potential risk of enamel fluorosis development (strength of evidence: D)
- When the potential risk of enamel fluorosis development is a concern, suggest ready-to-feed formula or powdered or liquid concentrate formula reconstituted with water that either is fluoride free or has low concentrations of fluoride (strength of evidence: C)
As early childhood, the first 2-3 years of life, is a critical period for early-erupting permanent teeth such as the first permanent molars and maxillary permanent incisors to develop and mature, the benefit and risk of fluoride should be carefully considered in the recommendation. Fluoride Science identifies the following factors that warrant a consideration:
- Available scientific evidence points to a positive association between the use of infant formula mixed with fluoridated water and mild fluorosis.4,5,7,9 However, when these studies were conducted, fluoridation levels in drinking water were greater than that of today in the US (1 mg/L with a temperature-based range of 0.7-1.2 mg/L from 1962 to 2015, but now standardized at 0.7 mg/L). Therefore, the odds and significance of the association is likely smaller today.
- Systemically and topically available fluoride helps make children’s teeth more resistant to dental caries.10,11 Dental caries has lifelong oral health consequences and negative impact for oral health-related quality of life (OHRQoL),11 while mild enamel fluorosis, a subtle cosmetic change to the enamel, has reportedly none to even a positive effect for one’s OHRQoL.12,13
- The use of ready-to-feed formula or liquid or powdered concentrate formula mixed with either low-fluoride or fluoride-free water (i.e. deionized, purified, demineralized, distilled water, or water produced through reverse osmosis) would reduce fluoride intake from infant formula but would not eliminate the risk of fluorosis development.8
Systematic review on this topic:
Hujoel PP et al. (JADA. 2009)4
The authors identified 19 original studies (combined data for approximately 17,429 subjects with ages ranging from 2-17 years) for a systematic review regarding the risk of developing enamel fluorosis associated with use of infant formula. Of 19 studies, 18 were retrospective, and authors noted a wide range of limitations in infant formula data such as unknown types and frequency of formula consumption. None of the study reported data regarding quantity of infant formula consumed or the fluoride level of the infant formula measured at the time of consumption. On the basis of 17 studies that reported odds ratios (OR), infant formula consumption was associated with a higher prevalence of enamel fluorosis in the permanent dentition (summary OR=1.8, 95% CI=1.4–2.3). There was significant heterogeneity among studies (I2=66 percent, p<.0001) and evidence of publication bias (by Egger test, P =.002). A meta-regression analysis indicated that the reported fluorosis risk associated with infant formula consumption increased significantly as the fluoride in the water supply increased (OR 1.05, 95 percent CI 1.02–1.09). Authors could not determine whether liquid or powder infant formula with or without reconstitution affected fluorosis risk differently, as only a few studies provided such detailed information, or if it was the fluoride in the infant formula that caused the fluorosis ruling out other explanations.
- AAP Section on Breastfeeding. Policy statement on breastfeeding and the use of human milk. Pediatrics. 2012;129(3):e827-41
- Centers of Disease Control and Prevention. Breastfeeding Report Card. United States/ 2014. Available at https://www.cdc.gov/breastfeeding/pdf/2014breastfeedingreportcard.pdf
- Koparal E, Ertugrul F, Oztekin K. Fluoride levels in breast milk and infant foods. J Clin Pediatr Dent. 2000;24(4):299-302
- Hujoel PP, Zina LG, Moimaz AS, Cunha-Cruz J. Infant formula and enamel fluorosis. A systematic review. JADA. 2009;140(7):841-54
- Siew C, Strock S, RIstic H et al. Assessing a potential risk factor for enamel fluorosis. A preliminary evaluation of fluoride content in infant formulas. JADA. 2009;140(10):1228-36
- Institute of Medicine. Dietary reference intakes for calcium, phosophorus, magnesium, vitamin D, and fluoride. Washington, DC. National Academies Press. 1997.
- Levy SM. Broffitt B, Marshall TA et al. Associations between fluorosis of permanent incisors and fluoride intake from infant formula, other dietary sources and dentifrice during early childhood. JADA. 2010;141(10):1190-1201
- Berg J, Gerweck C, Hujoel PP et al. Evidence-based clinical recommendations regarding fluoride intake from reconstituted infant formula and enamel fluorosis. JADA. 2011;142(1):79-87
- Do LG, Levy SM, Spencer AJ. Association between infant formula feeding and dental fluorosis and caries in Australian children. J Public Health Dent. 2012;72:112-121
- Adair SM, Bowen WH, Burt BA et al. Recommendations for using fluoride to prevent and control dental caries in the United States. MMWR. 2001;50(RR14):1-42
- Iida H, Kumar JV. The association between enamel fluorosis and dental caries in US school children. JADA. 2009;140:855-62
- Onoriobe U, Rozier RG, Cantrell J, King RS. Effects of enamel fluorosis and dental caries on Quality of Life. J Dent Res. 2014;93(10):972-9
- Chankanka O, Levy SM, Warren JJ et al. A literature review of aesthetic perceptions of dental fluorosis and relatinships with psychosocial aspects/oral health-related quality of life. Community Dent Oral Epidemiol. 2010;38:97-109
- Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation
- Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association
- Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water