Clinical Trial

Vitamin E Pharmacokinetics and Biomarkers in Women

Study Description

Vitamin E Pharmacokinetics and Biomarkers in Normal and Obese Women

Background: - 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. Eligibility: - 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. Design: - 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.

Location

Locations Selected Location

Methods

Pharmaceutical medication involved Pharmaceutical medication involved
Patients and healthy individuals accepted Patients and healthy individuals accepted

Drug - Alpha Tocopherol Vitamin E

Deuterated vitamin E, oral and intravenous, at doses of 2mg, 5mg, 7.5mg, 10mg and 30mg.

Vitamin C

Oral vitamin C, one gram daily.

Additional Information

Official Study Title

Vitamin E Pharmacokinetics and Biomarkers in Women

Clinical Trial ID

NCT00862433

ParticipAid ID

Yer0Eb