Inflammation, Insulin Resistance, Obesity
Conditions
Keywords
25-hydroxyvitamin D, Parathyroid hormone, Lean mass, Muscular strength, Glucose tolerance
Brief summary
The study was designed to assess the effects of vitamin D supplementation during exercise training on body composition, muscle function, and glucose tolerance. The investigators hypothesis for these studies is that vitamin D supplementation enhances exercise-induced increases in strength and lean mass, potentially through enhancing insulin sensitivity and reducing inflammation.
Detailed description
The study was designed to assess the effects of vitamin D supplementation during exercise training on body composition, muscle function, and glucose tolerance. It was a double-blind, randomized, placebo-controlled, clinical trial with participants randomized into either a 4,000 IU/day vitamin D or placebo group and all participants completed 12 wks (3 d/wk) of exercise training.
Interventions
DIETARY_SUPPLEMENTVitamin D
4000 IU of vitamin D per day for 12 weeks.
DRUGPlacebo
Placebo (microcrystalline cellulose) ingestion each day for 12 weeks.
Sponsors
Purdue University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Physical activity scores in the low to very low category * Fitness estimations in the below average or lower categories * body mass index scores \>24.9 indicating overweight or obesity.
Exclusion criteria
* Use of tanning booths or other artificial UV light exposure * High baseline vitamin D and calcium intake * Plans to visit sunny/warm destinations during the winter months/study period * History or presence of metabolic disease, type 2 diabetes, eating disorders, gastrointestinal disorders, pregnancy or lactation * Use of drugs to treat obesity (last 12 weeks) * Use of over the counter anti-obesity agents (last 12 weeks) * Recent initiation of an exercise program (last four weeks).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle Function | three months | The primary endpoint is the change in lean mass (kilograms) after the three month resistance exercise intervention. |
| Glucose Tolerance | three months | The primary endpoint is the change in the area under the glucose curve following an oral glucose tolerance test prior to and after the three month intervention. |
| Inflammation | three months | The primary endpoint is the change in C reactive protein after the three month intervention |
Countries
United States
Participant flow
Recruitment details
Recruitment Start Sept 2008 Recruitment at Purdue University
Pre-assignment details
Following participant recruitment, baseline testing was completed prior to enrollment, study initiation and group assignment.
Participants by arm
| Arm | Count |
|---|---|
| Vitamin D Participants in this arm consumed a 4000 IU vitamin D3 supplement daily for 12 weeks while participating in a resistance exercise training program. | 17 |
| Placebo Participants in this arm consumed a placebo (microcrystalline cellulose) daily for 12 weeks while participating in a resistance exercise training program. | 17 |
| Total | 34 |
Baseline characteristics
| Characteristic | Placebo | Vitamin D | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 17 Participants | 17 Participants | 34 Participants |
| Age, Continuous | 26.2 years STANDARD_DEVIATION 5.1 | 26 years STANDARD_DEVIATION 4.5 | 26.1 years STANDARD_DEVIATION 4.8 |
| Region of Enrollment United States | 17 participants | 17 participants | 34 participants |
| Sex: Female, Male Female | 10 Participants | 10 Participants | 20 Participants |
| Sex: Female, Male Male | 7 Participants | 7 Participants | 14 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 |
Outcome results
Primary
Glucose Tolerance
The primary endpoint is the change in the area under the glucose curve following an oral glucose tolerance test prior to and after the three month intervention.
Time frame: three months
Population: Power statistical calculation was completed based on 80% power and error on lean mass measurement.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Vitamin D | Glucose Tolerance | -18.0 mmol/L/120 min | Standard Deviation 63.4 |
| Placebo | Glucose Tolerance | -25.7 mmol/L/120 min | Standard Deviation 31.1 |
Primary
Inflammation
The primary endpoint is the change in C reactive protein after the three month intervention
Time frame: three months
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Vitamin D | Inflammation | 0.64 mg/L | Standard Deviation 1.62 |
| Placebo | Inflammation | -0.33 mg/L | Standard Deviation 2.6 |
Primary
Muscle Function
The primary endpoint is the change in lean mass (kilograms) after the three month resistance exercise intervention.
Time frame: three months
Population: Power statistical calculation was completed based on 80% power and error on lean mass measurement.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Vitamin D | Muscle Function | 1.14 kilograms | Standard Deviation 1.22 |
| Placebo | Muscle Function | 1.50 kilograms | Standard Deviation 1.16 |