The Effect of Vitamin C on Growth Hormone Secretion

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.

Study Overview

• Status: Withdrawn
• Conditions: Obese; Disorder of Vitamin C; Growth Hormone Secretion Abnormality
• Intervention / Treatment: Dietary supplement: Placebo; Dietary supplement: Vitamin C 250 mg once daily; Dietary supplement: Vitamin C 1,000 mg once daily

• Study Type: Interventional
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02114
      • Massachusetts General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: QUADRUPLE

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: Vitamin C low dose; vitamin C 250 mg oral once daily	Dietary supplement: Vitamin C 250 mg once daily
ACTIVE_COMPARATOR: Vitamin C high dose; vitamin C 1,000 mg oral once daily	Dietary supplement: Vitamin C 1,000 mg once daily
PLACEBO_COMPARATOR: Placebo; Placebo oral once daily	Dietary supplement: Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in GH secretion at 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.	Change from Baseline to 4 weeks

Collaborators and Investigators

• Sponsor: Massachusetts General Hospital

Study record dates

Study Major Dates

• Study Start: December 1, 2013
• Primary Completion (ACTUAL): December 1, 2013
• Study Completion (ACTUAL): December 1, 2013

Study Registration Dates

• First Submitted: February 10, 2012
• First Submitted That Met QC Criteria: February 16, 2012
• First Posted (ESTIMATE): February 23, 2012

Study Record Updates

• Last Update Posted (ESTIMATE): December 13, 2013
• Last Update Submitted That Met QC Criteria: December 11, 2013
• Last Verified: December 1, 2013

More Information

Terms related to this study

• Keywords: low vitamin c; reduced growth hormone secretion
• Additional Relevant MeSH Terms: Congenital Abnormalities; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Protective Agents; Micronutrients; Antioxidants; Vitamins; Ascorbic Acid
• Other Study ID Numbers: 2011-P-002912