The goal of this clinical trial is to find out if vitamin D supplements help healthy adults maintain their cognitive and simple physical task performance and emotional state during highly stressful situations.
The main question it aims to answer is:
\- Does vitamin D help maintain cognitive and physical task performance and emotional state during highly stressful situations?
Researchers will compare vitamin D to placebo (a look-alike tablet that contains no active ingredients) to see if vitamin D better maintain cognitive and physical task performance and emotional state during highly stressful situations.
Participants will:
* Take vitamin D or placebo tablets daily for 8 weeks. * Perform cognitive and simple physical tasks and rate their emotional state under highly stressful situations. * Wear a stress belt that delivers mild electric shocks 1 - 5 times while participants are performing laboratory tasks. * Wear a wristwatch-shaped activity monitor for 9 weeks. * Visit the laboratory 5 times.
Male and non-pregnant, non-lactating females 18 to 40 (inclusive) years of age.
Females of child-bearing potential must be using some form of birth control, if sexually active (e.g., oral contraceptive, condom, intrauterine device, etc.)
Score of 80% or greater on a "Volunteer Comprehension Assessment" test. A maximum of two attempts is permitted.
Blood 25 hydroxy vitamin D [25(OH)D] levels at the Screening visit of 30 nmol/L (12 ng/mL) (inclusive) - < 75 nmol/L (30 ng/mL).
Contraindications due to vitamin D supplementation, including a history of hypercalcemia, malabsorption syndrome, hypervitaminosis D, or allergic/hypersensitivity reactions to vitamin D or a history of other adverse reactions to vitamin D supplementation.
Taking a vitamin D3 or D2 supplement or a supplement containing vitamin D3 or D2 (excluding vitamin D-fortified foods) during the participation. Volunteers who take vitamin D3 or D2 supplement before their participation can be eligible if they agree to stop taking the supplement(s) starting 1 month prior to the enrollment/baseline visit until the end of the post-supplementation visit. Blood 25(OH)D levels of the volunteers who stopped taking the supplements after the screening visit will be tested before the Enrollment/Baseline visit to ensure their 25(OH)D fall within the inclusionary ranges. Volunteers who are not able to stop taking vitamin D supplements or supplements containing vitamin D due to medical/health or any other reasons (especially if the volunteer is taking supplements containing vitamin D under the direction of a healthcare provider) are not eligible.
Not being able to tolerate electric shocks delivered through the stress belt.
Self-reported propensity for adverse skin reactions, such as excessive irritation, burning, itching, hives, and redness, in response to physical or heat stimuli.
Parallel
Vitamin D3 (Cholecalciferol)
Dietary supplement4,000 IU daily oral administration for 8 weeks.
Oral Placebo Tablet
Dietary supplementDaily administration of two oral placebo tablets for 8 weeks
Percentage correct for No-Go trials in the Go/No-Go task
Measure of cognitive performance. Percentage correct for No-Go trials.
Mean reaction time in the Psychomotor Vigilance Task
Measure of cognitive performance. Mean reaction time (millisecond)
Scale scores of The Automated Neuropsychological Assessment Metrics (ANAM) Mood Scale
The ANAM mood consists of seven scales: Vigor, Restless, Depression, Anger, Fatigue, Anxiety, and Happiness. For each scale, the range of score is 0 - 6, and a higher score indicates greater intensity of the respective mood.
Sway indices of Biosway
Sway indices will be obtained for Eyes open firm surface, Eyes closed firm surface, Eyes open foam surface, and Eyes closed foam surface. A higher index score indicates greater sway of the body.
Average Heart rate
Continuous measure of heart rate to assess autonomic nervous system activity before, during, and after the laboratory stress task.
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