Bone mass and soy isoflavones in socially housed, premenopausal macaques.
BACKGROUND
Soy consumption is associated with a lower incidence of hip fracture in Asian than in Western women, an effect often attributed to estrogen-like compounds (isoflavones) in soy. It is not known whether premenopausal soy exposure initiated in adulthood can increase bone mass and thereby reduce fracture risk.


OBJECTIVE
We aimed to determine whether a high-isoflavone soy diet influences bone mass in soy-naïve, premenopausal cynomolgus monkeys (Macaca fascicularis).


METHODS
Ninety-four skeletally mature females were randomly assigned to consume diets whose protein content came from either high-isoflavone soy or casein and lactalbumin. Animals were socially housed. Bone mass and circulating isoflavone concentrations were measured at baseline and 19 and 31 mo after the start of treatment; bone biomarkers were measured at baseline and 31 mo.


RESULTS
There were no significant differences at any timepoint in whole-body bone mineral content between casein-fed (112.5 +/- 2.1, 119.2 +/- 1.9, and 120.7 +/- 2.1 g) and soy-fed (117.2 +/- 2.1, 122.4 +/- 2.0, and 125.4 +/- 2.3 g; P=0.12) monkeys. Similar results were seen for spinal bone mineral density (casein-fed: 0.46 +/- 0.01, 0.50 +/- 0.01, and 0.52 +/- 0.01 g/cm(2); soy-fed: 0.47 +/- 0.01, 0.51 +/- 0.01, and 0.52 +/- 0.01 g/cm(2); P=0.30) and bone biomarker measurements-bone-specific alkaline phosphatase (soy-fed: 82.3 +/- 4.1 and 63.2 +/- 3.4 ng/mL; casein-fed: 94.1 +/- 4.5 and 61.7 +/- 4.3 ng/mL; P=0.22) and C-terminal crosslink of type 1 collagen (soy-fed: 0.944 +/- 0.06 and 0.89 +/- 0.08 nmol/L; casein-fed: 0.97 +/- 0.07 and 0.78 +/- 0.06 nmol/L; P=0.20).


CONCLUSIONS
A soy diet high in isoflavones does not significantly affect bone characteristics in initially soy-naïve premenopausal monkeys.
Lees
Cynthia J
CJ
Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-040, USA. clees@wfubmc.edu
Kaplan
Jay R
JR
Chen
Haiying
H
Jerome
Christopher P
CP
Register
Thomas C
TC
Franke
Adrian A
AA
D015502:Absorptiometry, Photon; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D002364:Caseins / Q000008:administration & dosage; D024042:Collagen Type I / Q000097:blood; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D007529:Isoflavones / Q000008:administration & dosage* / Q000097:blood; D007768:Lactalbumin / Q000008:administration & dosage; D008159:Lumbar Vertebrae / Q000502:physiology; D008252:Macaca fascicularis / Q000378:metabolism*; D010455:Peptides / Q000097:blood; D011897:Random Allocation; D012919:Social Behavior; D030262:Soybean Proteins / Q000008:administration & dosage*
D002364:Caseins; D024042:Collagen Type I; D004044:Dietary Proteins; D007529:Isoflavones; D010455:Peptides; D030262:Soybean Proteins; C052929:collagen type I trimeric cross-linked peptide; D007768:Lactalbumin; D000469:Alkaline Phosphatase