Associations Between Feeding Mode and Hair Manganese Concentrations in Infants

Open Access
- Author:
- Rink, Stephanie Marie
- Graduate Program:
- Nutrition
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 02, 2012
- Committee Members:
- Katarzyna Kordas, Thesis Advisor/Co-Advisor
- Keywords:
- manganese
hair
toxicity
infant
breastfeeding
infant formula - Abstract:
- Manganese (Mn) is an essential nutrient, required for growth, development, and health. However, at toxic levels Mn has been shown to lead to cognitive and behavioral deficits in infants and children. Mn toxicity from environmental exposures such as air and water has been associated with decreased intelligence quotient (IQ), externalizing and internalizing behaviors, hyperactivity, and impulsivity. Infant formulas are highly concentrated sources of Mn, containing as much as 50-80 times the amount of Mn as human breast milk. Despite the extreme differences in Mn concentration between infant formula and breast milk, formula has not been well studied as a source of exposure to Mn. The present study investigated Mn status in formula fed and breastfed infants to determine the deposition of Mn from dietary sources in hair. Infants 3-6 months of age and their mothers were recruited from State College, Pennsylvania, and the surrounding area. Infants were either predominantly breastfed (n=34) or predominantly formula fed (n=19). Hair samples were collected from mothers and infants, and were analyzed for Mn, arsenic (As), cadmium (Cd), and lead (Pb). Mothers provided tap water samples from home, which were analyzed for Mn, As, Cd, and Pb. Infant formula samples were also collected for infants who were formula fed, and were analyzed for Mn. Infant and maternal hair concentrations were within normal ranges for Mn, As, and Cd. Infants had slightly elevated Pb as measured in hair (mean: 6.22 µg/g), but mothers did not (mean: 0.34 µg/g). Tap water samples were not elevated in Mn, As, Cd, or Pb compared to acceptable limits, though Pb concentration was significantly higher in tap water samples from breastfed infants than from formula fed infants (means: 1.77 vs. 0.82 µg/g, respectively). Infants who were breastfed did not differ in hair Mn concentrations from infants who were formula fed. Salient predictors of maternal hair Mn concentrations included water Mn concentration, employment status, and education. Maternal hair Mn concentration and infant hair As concentration were significant predictors of infant hair Mn concentration in the fully adjusted regression model. The present findings suggest that ingestion may not be an important exposure mechanism for Mn toxicity in infants compared to environmental exposures. Future studies should investigate co-exposure of Mn and As in central Pennsylvania, and should expand upon present findings indicating limited impact of dietary exposure to Mn during infancy.