Soy protein and bone mineral density in older men and women: A randomized trial

Newton, K.M.; LaCroix, A.Z.; Levy, L.; Li, S.S.; Qu, P.; Potter, J.D.; Lampe, J.W.

doi:10.1016/j.maturitas.2006.04.011

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Volume 55, Issue 3 , Pages 270-277, 20 October 2006

Soy protein and bone mineral density in older men and women: A randomized trial☆

K.M. Newton
- Group Health Cooperative, Seattle, WA, USA
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Corresponding author at: Center for Health Studies, Group Health Cooperative, 1730 Minor Ave., Ste 1600, Seattle, WA 98101, USA. Tel.: +1 206 287 2973; fax: +1 206 287 2871.
A.Z. LaCroix
- Group Health Cooperative, Seattle, WA, USA
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Research Center, USA
L. Levy
- Fred Hutchinson Cancer Research Center, USA
S.S. Li
- Fred Hutchinson Cancer Research Center, USA
P. Qu
- Group Health Cooperative, Seattle, WA, USA
J.D. Potter
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Research Center, USA
J.W. Lampe
- Department of Epidemiology, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Research Center, USA

Received 19 August 2005; received in revised form 12 April 2006; accepted 15 April 2006.

Abstract

Objective

Test the hypothesis that soy isoflavone supplementation preserves bone mineral density (BMD) in men and women.

Methods

We conducted a controlled, parallel-arm, double-blinded trial with 145 participants, 50–80 years, with random assignment to soy beverage daily for 12 months. Active treatment (+ISO) received soy protein containing 83mg isoflavones (45.6mg genistein, 31.7mg daidzein), aglycone units; the comparison group (−ISO) received soy protein containing 3mg isoflavones. We measured BMD using dual-energy X-ray absorptiometry at the total hip and posterior–anterior spine (L1–L4) at baseline in 22 women and 123 men, and at 12 months in 13 women and 98 men. We used linear mixed models to test for an isoflavone effect on percentage BMD change from baseline in spine and hip.

Results

Among all participants, mean percent change in spine BMD (±S.E.) was 0.16±0.44 in −ISO (P=0.10) at 12 months. Treatment effects on spine BMD were significantly greater in women than men (P=0.01). At 12 months, in women, mean percent change was 0.58±0.70 in +ISO and −1.84±0.86 in −ISO (P=0.05); among men it was 1.32±0.53 in +ISO and 0.31±0.48 in −ISO (P=0.16). By comparison, percent change in hip BMD was similar in the treatment groups, and was not different between men and women. Mean percent change in hip BMD from baseline to 12 months was 0.54±0.38 in +ISO and −0.13±0.36 in −ISO (P=0.20) among all participants.