Obesity
Conditions
Keywords
Obesity, Metabolism
Brief summary
The reason for doing this study is to learn whether raising a person's vitamin D level from below normal to normal levels will improve his or her body's ability to use sugar. Vitamin D is well known to be an important vitamin for the development and maintenance of bones. Recently, scientists have learned that vitamin D may have a role in the prevention of cancer, diabetes, and autoimmune diseases. The investigators are specifically interested in studying this question in the overweight/obese population as they are at greater risk for both vitamin D deficiency and impaired ability to metabolize sugar (glucose intolerance). Primary Hypotheses: Vitamin D repletion (increasing the serum 25(OH)D level from ≤ 20 ng/ml to ≥ 30 ng/ml) will improve insulin sensitivity in individuals who are overweight/obese and insulin resistant. Secondary Hypotheses: 1.Vitamin D repletion will improve biomarkers of cardiovascular risk and inflammation (directly altering macrophage cytokine production and/or indirectly as a result of improvement in insulin sensitivity.) 2.30,000 IU (0.25 mg) weekly of cholecalciferol (vitamin D3) will raise serum 25(OH)D levels from ≤ 20 ng/ml to ≥ 30 ng/ml overweight/obese population.
Interventions
DIETARY_SUPPLEMENTVitamin D3 (cholecalciferol)
Vitamin D will be taken orally, 10,000 IU (0.25 mg) three times per week.
Sponsors
Rockefeller University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Nonsmoking men and women, ages 18-65 * Body mass index (BMI) ≥ 28 kg/m² and within 10% of maximum weight * Serum 25(OH)D level ≤ 20 ng/ml * Serum insulin level ≥ 7.2 mU/l * Willingness to maintain current body weight for the duration of the study * Willingness to maintain baseline lifestyle activities and routines for the duration of the study * Willingness to avoid the use of non-steroidal anti-inflammatory drugs (NSAIDS), including low-dose daily aspirin, for at least ten days prior to each admission (due to the potential effects of these agents on inflammatory markers.) * Willingness to avoid the use of all over-the-counter or prescription vitamins, dietary supplements, and herbal products during the study, with the exception of a basic multivitamin supplement. * If of childbearing potential, willingness to use highly effective contraception for the duration of the study.
Exclusion criteria
* Current tobacco smoking * History of bleeding or coagulation disorders * Gastrointestinal disease resulting in significant gastrointestinal dysfunction or malabsorption * History of diabetes, or diagnosed during screening OGTT * Current treatment with hypertensive medications * History of cardiovascular disease * Renal disease, as evidenced by a serum creatinine above the upper limit of normal on more than one screening visit * History of kidney stones * History of chronic hepatitis, or liver enzymes (AST or ALT) more than 2.5 times the upper limit of normal * Primary hyperparathyroidism or baseline hypercalcemia from any cause * Current treatment with over-the-counter or prescription weight loss medications, such as orlistat or sibutramine * History of bariatric surgery * Current treatment with any cholesterol-lowering medications, such as statins, niacin, fibrates, or ezetimibe * Blood pressure ≥ 145/90 after ten minutes of rest on more than one screen visit * Hyperthyroidism or untreated hypothyroidism. Subjects with chronic, treated, stable hypothyroidism may be included in the study at the discretion of the Principal Investigator. * Pregnancy, desired pregnancy, or lactation within the study period. * HIV, Hepatitis B and C * Medical conditions requiring daily calcium supplementation or antacid use * Use of medications known to interact with calcium or vitamin D metabolism (bisphosphonates, corticosteroids, thiazide diuretics, cholestyramine, colestipol, mineral oil, phenytoin, barbituates, dititalis glycosides, antacids) * Subjects with known hypersensitivity to cholecalciferol * Participation in an investigational drug study within one month of screening * History, physical, or laboratory findings suggestive of any other medical or psychological condition that would, in the opinion of the principal investigator, make the candidate ineligible for the study
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The primary outcome is change in insulin sensitivity over time, as measured by the glucose clamp, HOMA and OGTT. | 14 weeks |
Countries
United States
Outcome results
None listed