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Effect of Dietary Conjugated Linoleic Acid (CLA) on Parathyroid Hormone in Men

This study has been completed.
Information provided by (Responsible Party):
Hope Weiler, McGill University Identifier:
First received: January 23, 2008
Last updated: March 1, 2012
Last verified: March 2012

The parathyroid gland and its hormone have a major impact on the endocrine control of bone metabolism and mineralization and parathyroid hormone (PTH) has been identified in some epidemiological reports to relate adversely to mortality. Previously, the applicant has demonstrated in two models that dietary cis-9, trans-11 conjugated linoleic acid (CLA) reduces PTH by over 30% in as little as 4 weeks in male rats without adversely affecting bone density. Both bioactive PTH and intact PTH assays have been used and both are reduced by CLA. In one rat model, rats had normal PTH and a sub-group had high PTH due to chronic renal disease. In the second study, the rats were healthy young males and females. Regardless of the model and health state, PTH was reduced 30 to 40% by CLA. Of interest, other isoforms of CLA such as trans-10, cis-12 CLA do not alone result in reduced PTH. The selected CLA isomer proven to reduce PTH, cis-9, trans 11 CLA, is common to food products such as milk fat and beef and is thus more physiologically relevant to the human diet. The global objective of this study is to, for the first time; assess the effects of CLA on PTH in humans, specifically men.

Healthy men 19-53 years of age are selected since bone mass will have reached a peak by this age. Beginning with healthy relatively young men is important versus aging or ill individuals since the effect of CLA on PTH has not been examined and aging and illness might confound the results.

Subjects will be recruited using posters and local newspaper advertisements from the general population. Men (n=30/group) with healthy weights will be randomized to receive 0, 1.5 or 3 g CLA/d for a period of 4 months. At baseline, body weight will be assessed along with whole body bone, lean and fat mass using dual energy x-ray absorptiometry (DXA). Regional bone mass (lumbar spine, total hip, femoral neck) will also be examined using DXA. A blood sample will be taken in the fasted state between 9:00 and 10:00 to examine PTH, ionized Ca, and biomarkers of bone metabolism. After each 1 month on the study, the measurements will be repeated until end of study.

Dietary intake will be monitored along with a survey for possible mild side-effects such as gastrointestinal discomfort. Data will be examined using a mixed model for random (age, weight, vitamin D status) and fixed effects (diet, time) with post-hoc comparisons using Bonferroni correction.

Condition Intervention Phase
Healthy Dietary Supplement: Clarinol CLA Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Does Dietary Cis-9, Trans-11 Conjugated Linoleic Acid Reduce Parathyroid Hormone in Men?

Resource links provided by NLM:

Further study details as provided by Hope Weiler, McGill University:

Primary Outcome Measures:
  • Parathyroid Hormone [ Time Frame: 4 months ]

Enrollment: 55
Study Start Date: December 2008
Study Completion Date: December 2011
Primary Completion Date: March 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
CLA 1.5 g/d
Dietary Supplement: Clarinol CLA
0, 1.5 or 3.0 g/d dietary conjugated linoleic acids glycerides for 4 months, capsule form
Experimental: 2
CLA 3.0 g/d
Dietary Supplement: Clarinol CLA
0, 1.5 or 3.0 g/d dietary conjugated linoleic acids glycerides for 4 months, capsule form
Placebo Comparator: 3 Dietary Supplement: Clarinol CLA
0, 1.5 or 3.0 g/d dietary conjugated linoleic acids glycerides for 4 months, capsule form

  Show Detailed Description


Ages Eligible for Study:   19 Years to 53 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

The sample size will be 90 healthy men (n=30/group) based on the following inclusion criteria:

  • Healthy body weight based on body mass index (18.5 - 25 kg/m2 as per Health Canada
  • No chronic diseases
  • Normal bone mass for age (ie Z-score better than -1 where reference data available)
  • Vitamin D status within optimal range based on serum 25(OH)D (between 50 and 80 nmol/L of serum 25(OH)D with a median threshold of 75 nmol/L as set by international experts.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00608400

Canada, Quebec
Mary Emily Clinical Nutrition Research Unit
Sainte Anne de Bellevue, Quebec, Canada, H9X 3V9
Sponsors and Collaborators
McGill University
Principal Investigator: Hope A Weiler, PhD McGill University
  More Information

Responsible Party: Hope Weiler, Associate Professor, McGill University Identifier: NCT00608400     History of Changes
Other Study ID Numbers: HW-08-02
McGill University
Study First Received: January 23, 2008
Last Updated: March 1, 2012

Keywords provided by Hope Weiler, McGill University:
nutritional supplement

Additional relevant MeSH terms:
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs processed this record on September 21, 2017