The Effects of Increasing Serum Calcitriol on Energy and Fat Metabolism and Gene Expression

• Published in: Obesity (Silver Spring, Md.) Vol. 14; no. 10; pp. 1739 - 1746
• Main Authors: Boon, Niels, Hul, Gabby B. J., Sicard, Audrey, Kole, Eveline, Berg, Elisa R., Viguerie, Nathalie, Langin, Dominique, Saris, Wim H. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2006
• Subjects: Adipose Tissue - drug effects; Adipose Tissue - metabolism; Adult; Analysis of Variance; Blood Glucose - metabolism; Calcitriol - blood; Calcium - blood; Cholecalciferol - administration & dosage; Cholecalciferol - blood; Cholecalciferol - pharmacology; cholecalciferol supplementation; dietary calcium; Dietary Supplements; energy expenditure; Energy Metabolism - drug effects; Fatty Acid Synthases - genetics; Fatty Acids, Nonesterified - blood; Gene Expression - drug effects; Gene Expression - genetics; Glycerol - blood; Glycerolphosphate Dehydrogenase - genetics; Humans; Ion Channels - genetics; Male; Mitochondrial Proteins - genetics; PPAR gamma - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; serum 1,25‐OH2‐D3; Sterol Esterase - genetics; substrate metabolism; Time Factors; Uncoupling Protein 2; Vitamins - administration & dosage; Vitamins - blood; Vitamins - pharmacology
• ISSN: 1930-7381; 1930-739X
• DOI: 10.1038/oby.2006.200

Objective: Evidence from a number of investigations indicates that calcium intake could be inversely related to body weight through alterations in the 1,25‐OH2‐D3 metabolism. The objective of this study was to test whether energy and substrate metabolism and adipose tissue enzyme mRNA expression can be altered by changes in serum 1,25‐OH2‐D3 through oral cholecalciferol supplementation in non‐obese human subjects. Research Methods and Procedures: An intervention study was used with a treatment period of 7 days. During this intervention, energy expenditure (EE) and substrate metabolism were measured using indirect calorimetry at t = 0, 1, 3, and 7 days, and blood samples were obtained at t = −1, 0, 1, 2, 3, 5 and 7 days. Fat biopsies were obtained at t = 0 and 7 days for determination of expression of genes involved in lipolytic and lipogenic pathways. Subjects from the general community were studied in an ambulatory setting at a university hospital. Ten healthy young men (age, 28 ± 3 years; BMI, 25.5 ± 0.5 kg/m2) were recruited by local announcement, and all completed the study. All subjects received 2000 IU cholecalciferol/d for 7 days, and they were instructed to consume a low‐cholecalciferol, low‐calcium diet. EE, fat oxidation, and adipose tissue enzyme mRNA were the main outcome measures. Results: Despite a significant increase in serum 1,25‐OH2‐D3 concentration at t = 5 and 7 days, no significant differences in substrate and energy metabolism nor mRNA concentrations of different lipid metabolism‐related proteins were observed. Discussion: Seven‐day supplementation with 2000 IU cholecalciferol/d together with a decrease in dietary calcium intake does not affect EE or substrate metabolism nor gene expression of proteins related to fat metabolism, despite a significant increase in serum 1,25‐OH2‐D3 concentration.