The effect of soy protein isolate on bone metabolism.
OBJECTIVE
This double-blind, 15-month pilot study was designed to investigate the effect of soy protein isolate with varying concentrations of isoflavones on early postmenopausal bone loss and lipids.


METHODS
A total of 65 women, with a mean age of 55 years and 7.5 years since menopause, were randomized to one of three groups; soy protein with 96 mg isoflavones/day, soy with 52 mg isoflavones/day, or soy without isoflavones (< 4 mg isoflavones/day). Soy was given for 9 months and then discontinued; participants were followed for an additional 6 months. Bone mineral density (BMD) and blood lipids were measured during this time.


RESULTS
Measurement of serum isoflavones at 3 months showed dose-related increases in the three groups. There was no significant effect of the soy supplements on BMD of the spine or femoral neck in any of the three groups. BMD increased significantly in the trochanter at 9 months (P = 0.0219) and at 15 months (P < 0.05) in the group given isoflavone-free soy compared with the other two groups. There was no significant effect of soy on lipid metabolism at the end of the intervention.


CONCLUSIONS
The present study did not find a significant positive effect of soy protein isolate supplemented with isoflavones on BMD and the serum lipid profile in early postmenopausal women.
Gallagher
J Christopher
JC
Bone Metabolism Unit, School of Medicine and the Osteoporosis Research Center, Creighton University, Omaha, NE, USA. jcg@creighton.edu
Satpathy
Ruby
R
Rafferty
Karen
K
Haynatzka
Vera
V
D000328:Adult; D001059:Apoproteins / Q000097:blood; D015519:Bone Density; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000627:therapeutic use*; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000517:prevention & control*; D008517:Phytotherapy; D010865:Pilot Projects; D010936:Plant Extracts / Q000008:administration & dosage / Q000627:therapeutic use*; D030262:Soybean Proteins; D016896:Treatment Outcome; D014280:Triglycerides / Q000097:blood
D001059:Apoproteins; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007529:Isoflavones; D008055:Lipids; D010936:Plant Extracts; D030262:Soybean Proteins; D014280:Triglycerides; D015675:Osteocalcin; D002784:Cholesterol