title: Does taurine deficiency cause metabolic bone disease and rickets in polar bear cubs raised in captivity?
abstract: Rickets and fractures have been reported in captive polar bears. Taurine (TAU) is key for the conjugation of ursodeoxycholic acid (UDCA), a bile acid unique to bears. Since TAU-conjugated UDCA optimizes fat and fat-soluble vitamin absorption, we asked if TAU deficiency could cause vitamin D malabsorption and lead to metabolic bone disease in captive polar bears. We measured TAU levels in plasma (P) and whole blood (WB) from captive and free-ranging cubs and adults, and vitamin D3 and TAU concentrations in milk samples from lactating sows. Plasma and WB TAU levels were significantly higher in cubs vs captive and free-ranging adult bears. Vitamin D in polar bear milk was 649.2 +/- 569.2 IU/L, similar to that found in formula. The amount of TAU in polar bear milk is 3166.4 +/- 771 nmol/ml, 26-fold higher than in formula. Levels of vitamin D in bear milk and formula as well as in plasma do not indicate classical nutritional vitamin D deficiency. Higher dietary intake of TAU by free-ranging cubs may influence bile acid conjugation and improve vitamin D absorption.
authors.affiliation: The University of Tennessee Health Science Center, USA. rchesney@utmem.edu
authors.forename: Russell W
authors.initials: RW
authors.lastname: Chesney
authors.forename: Gail E
authors.initials: GE
authors.lastname: Hedberg
authors.forename: Quinton R
authors.initials: QR
authors.lastname: Rogers
authors.forename: Ellen S
authors.initials: ES
authors.lastname: Dierenfeld
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Hollis
authors.forename: Andrew
authors.initials: A
authors.lastname: Derocher
authors.forename: Magnus
authors.initials: M
authors.lastname: Andersen
mesh_terms: D000818:Animals; D001851:Bone Diseases, Metabolic / Q000209:etiology*; D002851:Chromatography, High Pressure Liquid; D008892:Milk / Q000737:chemistry; D012279:Rickets / Q000209:etiology*; D013654:Taurine / Q000032:analysis / Q000172:deficiency*; D001503:Ursidae; D014807:Vitamin D / Q000032:analysis
chemical_list: D014807:Vitamin D; D013654:Taurine