The Effect of Vitamin C on Growth Hormone Secretion

The Effect of Vitamin C on Growth Hormone Secretion


Lead Sponsor: Massachusetts General Hospital

Source Massachusetts General Hospital
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.

Overall Status Withdrawn
Start Date 2013-12-01
Completion Date 2013-12-01
Primary Completion Date 2013-12-01
Phase Phase 2
Study Type Interventional
Primary Outcome
Measure Time Frame
Change from Baseline in GH secretion at 4 weeks Change from Baseline to 4 weeks

Intervention Type: Dietary Supplement

Intervention Name: Placebo

Arm Group Label: Placebo

Intervention Type: Dietary Supplement

Intervention Name: Vitamin C 250 mg once daily

Arm Group Label: Vitamin C low dose

Intervention Type: Dietary Supplement

Intervention Name: Vitamin C 1,000 mg once daily

Arm Group Label: Vitamin C high dose



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.



Minimum Age:

18 Years

Maximum Age:

60 Years

Healthy Volunteers:


Overall Official
Last Name Role Affiliation
Hideo Makimura, MD, PhD Principal Investigator Massachusetts General Hospital
Facility: Massachusetts General Hospital
Location Countries

United States

Verification Date


Responsible Party

Type: Principal Investigator

Investigator Affiliation: Massachusetts General Hospital

Investigator Full Name: Hideo Makimura

Investigator Title: Assistant Professor of Medicine

Has Expanded Access No
Condition Browse
Number Of Arms 3
Arm Group

Label: Vitamin C low dose

Type: Active Comparator

Description: vitamin C 250 mg oral once daily

Label: Vitamin C high dose

Type: Active Comparator

Description: vitamin C 1,000 mg oral once daily

Label: Placebo

Type: Placebo Comparator

Description: Placebo oral once daily

Study Design Info

Allocation: Randomized

Intervention Model: Parallel Assignment

Primary Purpose: Treatment

Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

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