title: Breast feeding and formula feeding affect differently plasma thyroid hormone concentrations in infant baboons.
abstract: We tested the hypothesis that plasma thyroid hormone levels in infant baboons are differentially affected by breast-feeding and nursery rearing. Infant baboons were breast-fed (n = 17), or fed formulas with a high polyunsaturated to saturated fat ratio (P/S) (n = 13), or a low P/S formula (n = 14). Plasma total triiodothyronine (T3) and free T3 (fT3) concentrations increased from 4 to 14 weeks of age in infants fed either formula, but decreased in breast-fed infants. At 9 and 14 weeks of age, infants fed the formulas averaged 31% higher T3 and 53% higher fT3 concentrations compared with breast-fed infants. Although T3 concentrations of the high P/S formula group compared with the low P/S formula group were not different at any single age, from 4 to 14 weeks the T3 averaged 19% higher in the high P/S formula group. Plasma total thyroxine (T4) or free T4 (fT4) concentrations were not significantly different among the diet groups during the preweaning period. In summary, formula-fed infants maintained higher plasma T3 and fT3 levels compared with breast-fed infants in the late preweaning period.
authors.affiliation: Department of Physiology and Medicine, University of Texas Health Science Center, San Antonio.
authors.forename: D S
authors.initials: DS
authors.lastname: Lewis
authors.forename: C A
authors.initials: CA
authors.lastname: McMahan
authors.forename: G E
authors.initials: GE
authors.lastname: Mott
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn / Q000097:blood* / Q000378:metabolism / Q000502:physiology; D000833:Animals, Suckling / Q000097:blood* / Q000502:physiology; D001903:Bottle Feeding; D005223:Fats / Q000378:metabolism; D005224:Fats, Unsaturated / Q000378:metabolism; D005260:Female; D005526:Food, Formulated; D008074:Lipoproteins / Q000097:blood; D008297:Male; D010215:Papio / Q000378:metabolism* / Q000502:physiology; D013974:Thyroxine / Q000097:blood*; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D005223:Fats; D005224:Fats, Unsaturated; D008074:Lipoproteins; D014284:Triiodothyronine; D013974:Thyroxine