Effects of Vitamin D Supplementation in Obesity

Obesity is an increasing health problem with numerous metabolic complications. Vitamin D deficiency is common in obesity, and in epidemiological studies vitamin D deficiency has been linked to metabolic complications, such as type 2 diabetes, insulin resistance and cardiovascular disease, as well as myopathy, osteoporosis and depression. In obesity, a low grade inflammation is present in the fat tissue, thereby releasing inflammatory molecules to the blood stream. In cell line studies as well as small clinical studies vitamin D has been shown to have the ability to reduce inflammation and cell growth. In the present study the investigators wish to investigate the effect of vitamin D on fat-, muscle and bone metabolism. 30 healthy obese subjects will be treated with cholecalciferol 175 micrograms daily for 6 months and will be compared with 30 healthy obese subjects treated with placebo. The investigators hypothesize that restoring vitamin D levels in vitamin D deficient obese subject will reduce inflammation and thereby reduce obesity-related complications. The effect will be evaluated as follows: Levels of circulating inflammatory markers will be examined in blood samples collected prior to and after treatment. Effects on fat- and muscle metabolism will be evaluated in fat- and muscle samples taken before and after treatment. Effects on fat distribution will be evaluated by MRI scan before and after treatment. Effects on insulin sensitivity will be evaluated by hyperinsulinaemic euglycaemic clamp performed on a subgroup of subjects with impaired fasting glucose. Effects on bone marrow density will be evaluated by DEXA scans before and after treatment. Effects on quality of life and depression score will be evaluated by questionnaires used before and after treatment.

Inclusion Criteria: Healthy obese (BMI 30 - 45 kg/m2) 25(OH) vitamin D < 50 nmol/l Exclusion Criteria: Diabetes, Pregnancy or non-safe contraception, Vitamin D treatment within 3 months, Hypercalcaemia, renal failure, Liver failure, non eligibility for MRI-scan, Severe osteomalacia, Allergy towards study drug

Bislev LS, Wamberg L, Rolighed L, Grove-Laugesen D, Rejnmark L. Effect of Daily Vitamin D3 Supplementation on Muscle Health: An Individual Participant Meta-analysis. J Clin Endocrinol Metab. 2022 Apr 19;107(5):1317-1327. doi: 10.1210/clinem/dgac004.