Disorder of Vitamin C, Growth Hormone Secretion Abnormality, Obese
Conditions
Keywords
low vitamin c, reduced growth hormone secretion
Brief summary
Obesity is associated with reduced growth hormone (GH) secretion. GH secretion is regulated by nutritional stimuli including fasting, insulin, glucose and free fatty acids. However, the role of micronutrients, such as vitamins, on GH secretion has not been investigated in much detail. Vitamin C levels are also reduced in obesity, and the investigators recently demonstrated a possible role for dietary vitamin C intake in the regulation of GH secretion in two preliminary retrospective studies. The investigators therefore propose a more detailed prospective physiological study to examine the effects of increasing dietary vitamin C intake on GH secretion in a physiologic, intervention study. The investigators hypothesize that increasing vitamin C concentrations in obese subjects with sub-optimal plasma vitamin C levels and reduced GH secretion will increase GH secretion.
Interventions
DIETARY_SUPPLEMENTPlacebo
DIETARY_SUPPLEMENTVitamin C 250 mg once daily
DIETARY_SUPPLEMENTVitamin C 1,000 mg once daily
Sponsors
Massachusetts General Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
No
Inclusion criteria
1. Men and women age 18-60 2. BMI ≥ 30 kg/m2 3. Waist circumference ≥ 102 cm in men and ≥ 88 cm in women 4. Plasma vitamin C concentration ≤ 23 µmol/l 5. Peak stimulated GH ≤ 4.2 µg/l upon GHRH-arginine stimulation test
Exclusion criteria
1. History of hypopituitarism, pituitary surgery, pituitary/brain radiation, recent traumatic brain injury or any other condition known to affect the GH axis. 2. History of severe chronic illness including anemia, chronic kidney disease, liver disease, oxygen dependent COPD or HIV 3. Subjects on testosterone, glucocorticoids, anabolic steroids, GHRH, GH or IGF-1 within 3 months of enrollment 4. Use of dietary supplements including vitamin C or once daily multi-vitamins 5. Subjects with Hgb \< 912 g/dL, SGOT \> 2.5x upper limit of normal or Creatinine \> 1.5 mg/dL 6. Subjects with poorly controlled diabetes, defined as HbA1c \> 8%. 7. Changes in lipid lowering or anti-hypertensive regimen within 3months of screening 8. Subject is currently enrolled in another investigational device or drug trial(s), or subject has received other investigational agent(s) within 28 days of baseline visit 9. Any condition judged by the patient's physician to cause this clinical trial to be detrimental to the patient.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change from Baseline in GH secretion at 4 weeks | Change from Baseline to 4 weeks | GH secretion will be assessed by overnight frequent blood sampling to assess maximum GH, nadir GH, mean overnight GH, as well as parameters of pulsatile secretion. |
Countries
United States
Outcome results
None listed