British Journal of Nutrition

Human and Clinical Nutrition

Reported zinc, but not copper, intakes influence whole-body bone density, mineral content and T score responses to zinc and copper supplementation in healthy postmenopausal women

Forrest H. Nielsena1 c1, Henry C. Lukaskia2, LuAnn K. Johnsona1 and Z. K. (Fariba) Rougheada3

a1 United States Department of Agriculture, Agricultural Research Service (USDA, ARS), Grand Forks Human Nutrition Research Center, Grand Forks, ND, USA

a2 Department of Physical Education, Exercise Science and Wellness, University of North Dakota, Grand Forks, ND, USA

a3 Nestlé Nutrition R and D Center Minneapolis, Minnetonka, MN, USA

Abstract

A supplementation trial starting with 224 postmenopausal women provided with adequate vitamin D and Ca was conducted to determine whether increased Cu and Zn intakes would reduce the risk for bone loss. Healthy women aged 51–80 years were recruited for a double-blind, placebo-controlled study. Women with similar femoral neck T scores and BMI were randomly assigned to two groups of 112 each that were supplemented daily for 2 years with 600 mg Ca plus maize starch placebo or 600 mg Ca plus 2 mg Cu and 12 mg Zn. Whole-body bone mineral contents, densities and T scores were determined biannually by dual-energy X-ray absorptiometry, and 5 d food diaries were obtained annually. Repeated-measures ANCOVA showed that bone mineral contents, densities and T scores decreased from baseline values to year 2. A priori contrasts between baseline and year 2 indicated that the greatest decreases occurred with Cu and Zn supplementation. Based on 5 d food diaries, the negative effect was caused by Zn and mainly occurred with Zn intakes ≥ 8·0 mg/d. With Zn intakes < 8·0 mg/d, Zn supplementation apparently prevented a significant decrease in whole-body bone densities and T scores. Food diaries also indicated that Mg intakes < 237 mg/d, Cu intakes < 0·9 mg/d and Zn intakes < 8·0 mg/d are associated with poorer bone health. The findings indicate that Zn supplementation may be beneficial to bone health in postmenopausal women with usual Zn intakes < 8·0 mg/d but not in women consuming adequate amounts of Zn.

(Received October 05 2010)

(Revised March 28 2011)

(Accepted March 28 2011)

(Online publication July 01 2011)

Key Words:

Correspondence:

c1 Corresponding author: Dr Forrest H. Nielsen, fax +1 701 795 8240, email forrest.nielsen@ars.usda.gov

Footnotes

Abbreviations: DXA, dual-energy X-ray absorptiometry; EAR, estimated average requirement

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