Vitamin E Pharmacokinetics and Biomarkers in Normal and Obese Women
- Vitamin E is an antioxidant that reduces the damaging effects of oxygen in the body. Most American men (90%) and women (96%) do not get enough vitamin E from their diets; however, the amount of vitamin E needed by the body has been studied only in men, not women. In addition, it is unknown whether another antioxidant, vitamin C, helps vitamin E in protecting the body. Because vitamin E is a fat-soluble vitamin, how much body fat a person has could affect the amount of vitamin E needed for protection.
Objectives: This study has three arms to examine vitamin E requirements:
- To determine the amount of fat required to get the best vitamin E absorption from a meal.
- To determine the amount (i.e., best dose) of vitamin E that must be consumed before it can be measured in the blood.
- To examine how vitamin E and vitamin C work together in the body, in conjunction with diet and vitamin supplements.
- Arms 1 and 2: Women between the ages of 18 and 40 years who have a normal weight and body mass index (BMI) of 27 or less.
- Arm 3: Women between the ages of 18 and 40 years who have a normal weight (BMI 27), who are overweight (BMI > 27), or who are overweight (BMI > 27) and have non insulin-dependent diabetes.
- Arm 1: Five studies, each lasting 1 month with 1 month off between studies (total study = 10 months). Participants will take 500 1,000 mg of vitamin C twice daily for 2 weeks before admission to the clinical center for 1 week.
- Study 1: Participants will eat breakfast containing a known amount of fat, after which they will take a vitamin E pill as well as receive an IV injection of vitamin E. Other foods contain only negligible amounts of vitamin E. Blood and urine samples will measure levels of vitamin E and other substances.
- Studies 2 5: Outpatient visits will consist of the same tests as in Study 1; however, the amount of fat in the breakfast will range from 0% to 40% in random order. During one of the studies, an adipose tissue biopsy will be collected to determine how much vitamin E is in the tissues.
- Arm 2: Five studies, each lasting 1 month with 1 month off between studies (total study = 10 months). Preparation for Arm 2 is the same as in Arm 1. The proportion of fat, muscle, and water in the body will also be measured.
- Study 1: Participants will eat breakfast containing 30% fat, after which they will take a vitamin E pill as well as receive an IV injection of vitamin E. Conditions and procedures are the same as in Arm 1.
- Studies 2 5: Outpatient visits will consist of the same tests as in Study 1; however, the amount of vitamin E in the breakfast will range from 2 to 30 mg in random order.
- Arm 3: Outpatient (2 to 6 weeks) and inpatient studies (4 to 6 weeks).
- Outpatient study: Participants will take 500 1,000 mg of vitamin C daily and provide blood and urine samples, as well as an adipose tissue sample.
- Inpatient studies: Two vitamin E inpatient studies. Before these begin, participants vitamin C blood levels will be reduced by means of a diet low in vitamin C. Blood tests will determine how quickly vitamin C leaves the body. Once the vitamin C level is reduced, the first vitamin E study will begin.
Study A: The procedure for this study is the same as in Arm 2, Study 1.
Study B: The procedure for this study is the same as in Study A, except that the participants blood vitamin C levels will be higher.
Dietary Supplement: Vitamin E
Dietary Supplement: Vitamin C
|Study Design:||Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Masking: Open Label
Primary Purpose: Prevention
|Official Title:||Vitamin E Pharmacokinetics and Biomarkers in Women|
- Measure Vitamin E Kinetics [ Time Frame: q 5 mins, 1-4 hrs ]
|Study Start Date:||March 2009|
|Estimated Study Completion Date:||December 2019|
|Estimated Primary Completion Date:||December 2018 (Final data collection date for primary outcome measure)|
Experimental: Arm 1
Description: Determine optimal fat content of meal for optimal absorption of vitamin E
|Dietary Supplement: Vitamin E|
Experimental: Arm 2
Determine optimal dose of vitamin E.
|Dietary Supplement: Vitamin E|
Experimental: Arm 3
Investigate the relationship between vitamin C status and vitamin E turnover
|Dietary Supplement: Vitamin E Dietary Supplement: Vitamin C|
Please refer to this study by its ClinicalTrials.gov identifier: NCT00862433
|Contact: Sebastian J Padayatty, M.D.||(301) firstname.lastname@example.org|
|Contact: Mark A Levine, M.D.||(301) email@example.com|
|United States, Maryland|
|National Institutes of Health Clinical Center, 9000 Rockville Pike||Recruiting|
|Bethesda, Maryland, United States, 20892|
|Contact: For more information at the NIH Clinical Center contact Patient Recruitment and Public Liaison Office (PRPL) 800-411-1222 ext TTY8664111010 firstname.lastname@example.org|
|Principal Investigator:||Mark A Levine, M.D.||National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)|