Original Communication
European Journal of Clinical Nutrition (2005) 59, 432–440. doi:10.1038/sj.ejcn.1602093 Published online 26 January 2005
Effect of dietary supplementation with conjugated linoleic acid on markers of calcium and bone metabolism in healthy adult men
Guarantor: KD Cashman.
Contributors: LD contributed to design, execution, analysis and writing of the study. CJ, AM, and APN contributed to the execution and analysis of the study. KDC and HMR contributed to design, analysis and writing of the study.
L Doyle1, C Jewell1, A Mullen3, A P Nugent3, H M Roche3 and K D Cashman1,2
- 1Department of Food and Nutritional Sciences, University College, Cork, Ireland
- 2Department of Medicine, University College, Cork, Ireland
- 3Unit of Nutrition, Department of Clinical Medicine, Trinity Centre for Health Sciences, St. James' Hospital, Dublin, Ireland
Correspondence: KD Cashman, Department of Food and Nutritional Sciences, University College, Cork, Ireland. E-mail: k.cashman@ucc.ie
Received 11 February 2004; Revised 19 July 2004; Accepted 14 October 2004; Published online 26 January 2005.
Abstract
Introduction:
Conjugated linoleic acid (CLA) has been shown to positively influence calcium and bone metabolism in experimental animals and cells in culture, but there are limited human data available.
Objective:
To investigate the effect of CLA supplementation on biomarkers of calcium and bone metabolism in healthy adult males.
Design:
The study consisted of a double-blind, placebo-controlled trial in which 60 healthy adult males (aged 39–64 y) were randomly assigned to receive daily either 3.0 g CLA isomer blend (50:50% cis-9,trans-11:trans-10,cis-12 isomers) or a palm/bean oil blend (placebo) for 8 weeks. Urine and blood samples were collected at weeks 0 and 8 and were analysed for biomarkers of calcium and bone metabolism.
Results:
Supplementation with CLA or placebo for 8 weeks had no significant effects on markers of bone formation (serum osteocalcin and bone-specific alkaline phosphatase) or bone resorption (serum C-telopeptide-related fraction of type 1 collagen degradation products, urinary N-telopeptide-related fraction of type 1 collagen degradation products, urinary pyridinoline and deoxypyridinoline), or on serum or urinary calcium levels. Baseline levels of these biochemical parameters were similar in both groups of subjects. While the placebo had no effect, CLA supplementation resulted in a three-fold increase (P<0.00001) in cis-9,trans-11 CLA isomer in total plasma lipids.
Conclusion:
Under the conditions tested in this double-blind, placebo-controlled trial in adult men, a CLA supplement of mixed isomers did not affect markers of calcium or bone metabolism. Further investigation of the effects of CLA on calcium and bone metabolism in other gender- and age-groups is warranted.
Sponsorship:
Irish Government.
Keywords:
conjugated linoleic acid, biomarkers of bone metabolism, human subjects
