Moderate exercise is thought to be one of the best known means to improve how insulin works in people. Taking vitamin C and vitamin E is also thought to have the same effect. This study is being done to see if taking vitamin C and vitamin E improves or hinders how insulin works when people do not exercise and when they do exercise.
The objective of the study is to determine in humans whether anti-oxidant supplementation with ascorbate (vitamin C) or R,R,R-α-tocopherol acetate (vitamin E) improves insulin sensitivity in the untrained state but blocks exercise-induced increases in insulin sensitivity and other adaptations to exercise. The results will provide new information on the roles of anti-oxidant supplementation in modifying insulin sensitivity, and will inform guidelines for anti-oxidant supplementation as an adjunct to exercise.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
1
Vitamin E 400 iu/dose daily times 56 days Vitamin C 500 mg/dose twice daily times 56 days
Grand Forks Human Nutrition Research Center
Grand Forks, North Dakota, United States
(1) Blood glucose and insulin following glucose challenge in non-exercising and exercising people (BMI 27 to 35) taking anti-oxidants (vitamin E and vitamin C) or placebo.
Individuals will be in placebo and vitamin supplemented groups in a cross-over design. A total of 6 oral glucose tolerance tests will be performed per subject in the study.
Time frame: 28 weeks
(1) Resting metabolic rate, body composition, plasma oxidative stress, plasma vitamin E and vitamin C levels in non-exercising and exercising people (BMI 27 to 35) taking anti-oxidants (vitamin E and vitamin C) or placebo.
Time frame: 28 weeks
(2) Fitness measures (heart rate, exercise work, VO2, VCO2, blood lactate) in non-exercising and exercising people (BMI 27 to 35) taking anti-oxidants (vitamin E and vitamin C) or placebo.
Time frame: 28 weeks
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