Protocol Number: 07-DK-0163

Title:

The Effect of Diet on Vascular Disease: A Study of Pre-Menopausal African American and Caucasian Women

Number:

07-DK-0163

Summary:

This study will examine the effect of the typical American diet on vascular disease risk in African-American and Caucasian women. Compared to other cultures, the American diet is high in fat. Fat in the typical American diet may explain why heart disease is the leading cause of death for American women.

Healthy pre-menopausal African-American and Caucasian women between 18 and 49 years of age who weigh less than 300 pounds may be eligible for this study.

Participants have 10 visits to the NIH Clinical Center to undergo the following procedures:

Visit 1

Medical history and physical exam, including questions about the subject's diet, exercise, family, education and employment.

Blood tests, urine tests and an electrocardiogram.

Visit 2

Brachial artery reactivity study: This test measures the rate at which blood flows through the brachial artery (a blood vessel in the arm). Ultrasound pictures of the arm are taken. Then a blood pressure cuff is placed on the arm and inflated for 5 minutes. After 5 minutes, the cuff is deflated and ultrasound pictures of the arm are taken again.

Glucose tolerance test: This test examines how well insulin is controlling the glucose (sugar) and fat in the blood. A catheter (plastic tube) is placed in a vein in each arm. The subject is given glucose through the catheter in one vein. After 20 minutes, a small amount of insulin is given through the same catheter. Blood samples are drawn through the catheter in the other arm at frequent intervals.

Visits 3-9

Dietary visits: Subjects come to the Clinical Center for 7 days to be weighed, eat breakfast and take home food for lunch, dinner, and snacks.

On one of these seven dietary visits, subjects have the following tests:

-CT scan to measure the amount of fat in the abdomen.

-DEXA scan to measure total body fat.

-Arm, leg, chest and abdomen skinfold thickness measurements.

-Waist, thigh and hip measurements.

Visits 10

Test Meal: This visit is done to determine how a single meal affects fat levels and vascular function. Height, weight and blood pressure are measured. Then, a catheter is placed in an arm vein and a blood sample is drawn. The brachial artery reactivity study is done as described for Visit 2. Then test meal consisting of a cheddar cheese omelet, orange juice and bagel with cream cheese is eaten. Blood is drawn and the brachial artery study is repeated at 2, 4 and 6 hours after the meal.

Sponsoring Institute:

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Recruitment Detail

Type: Participants currently recruited/enrolled

Gender: Female

Referral Letter Required: No

Population Exclusion(s): Male

Children

American Indian or Alaskan Native

Asian

Hispanic

Pacific Islander

Eligibility Criteria:

INCLUSION CRITERIA:

African American Women: Individuals will be considered to be African American if they self-identify as African American and were born in the United States. Further they must describe both parents as being African American and born in the United States.

Caucasian Women: Individuals will be considered to be Caucasian if they self-identify as Caucasian and were born in the United States. Further they must describe both parents as being Caucasian and born in the United States.

Healthy Volunteers: The potential enrollee must self identify as a normal volunteer and have this confirmed by having at the screening visit a normal complete blood count, glucose, BUN creatinine, liver and thyroid panel.

Age between 18 and 49 years: This age range is chosen because TG levels change at puberty and increase with age and postmenopausal status. However, we understand that vascular disease is not likely to be present in this age range. But our goal is not to detect vascular disease but to detect ethnic differences in the pathways that allow vascular disease to develop. Enrolling women between the ages of 18 and 49 years will minimize confounders and maximize our ability to detect differences in mechanism of action that are truly secondary to ethnicity rather than hormonal changes related to the life cycle.

Weight less than 136 kg (300 lbs): This weight restriction is necessitated by the limitations of the DXA scanner. The DXA platform cannot accommodate subjects who weigh more than 136 kg.

BMI between 20 and 45 kg/m(2): Women in both ethnic groups will be recruited across BMI nonobese and obese categories. Therefore we will enroll from each ethnic group 12 women with a BMI between 20 and 30 kg/m2 and 12 women with a BMI between 30 and 45 kg/m(2).

EXCLUSION CRITERIA:

Menopause: As the menopause can affect TG levels, menopausal women will be excluded. To ensure that menopausal women are excluded, FSH levels will be checked in women between the ages of 40 and 49 years. If the FSH level is elevated, the woman will be excluded.

Hysterectomy: The phase of the menstrual cycle affects TG levels. Therefore women will be studied between 0 and 10 days of their menstrual cycle. If a potential subject has had a hysterectomy we will not have a temporal way to determine what phase of the menstrual cycle she is in.

Irregular menses: If the subject has irregular menses it will not be possible to determine her follicular phase by counting the days from the onset of her menses.

Refusal to agree to use barrier contraception: The DXA scan and CT scan should not be performed if the participant is pregnant. In addition, TG levels are directly affected by pregnancy. Even though we will perform pregnancy tests within 7 days of each visit, we also require that the subject agree to abstinence or barrier contraception throughout the study.

Medications which affect parameters under investigation: Examples include corticosteroids, oral contraceptives, hypoglycemic (oral or injection), hypolipidemic, antihypertensive and antipsychotic agents. Oral contraceptives, in particular, are exclusion criteria because the estrogen component of oral contraceptives increase TG levels and would therefore obscure the effect of the test meal on TG levels.

Medical Conditions which affect parameters under investigation: Examples include diabetes, thyroid disease, liver disease, pancreatitis, nephrotic syndrome.

Current Smokers: Smoking can affect TG levels, endothelial function and insulin resistance. Therefore current smokers will be excluded. Women who were past smokers but have not smoked for one year prior to enrollment will be allowed to participate.

Hispanics: The relationship between TG and insulin resistance in Hispanic White women is midway between African American and Caucasian women. Therefore in this initial study to be able to determine the maximum ethnic difference in the relationship between TG and insulin resistance, we will enroll in this protocol study women who self-identify as African American and Caucasian and not enroll women who self-identify as Hispanic.

Special Instructions:

Currently Not Provided

Keywords:

Women

Healthy Volunteers

Triglyceride

Recruitment Keyword(s):

Healthy Volunteer

HV

Condition(s):

Cardiovascular Diseases

Vascular Disease

Inflammation

Insulin

Triglycerides

Investigational Drug(s):

None

Investigational Device(s):

None

Intervention(s):

None

Supporting Site:

National Institute of Diabetes and Digestive and Kidney Diseases

Contact(s):

Patient Recruitment and Public Liaison Office
Building 61
10 Cloister Court
Bethesda, Maryland 20892-4754
Toll Free: 1-800-411-1222
TTY: 301-594-9774 (local),1-866-411-1010 (toll free)
Fax: 301-480-9793

Electronic Mail:prpl@mail.cc.nih.gov

Citation(s):

Ferdinand KC. Coronary artery disease in minority racial and ethnic groups in the United States. Am J Cardiol. 2006 Jan 16;97(2A):12A-19A. Epub 2005 Dec 1. Review.

Schwartz EA, Reaven PD. Molecular and signaling mechanisms of atherosclerosis in insulin resistance. Endocrinol Metab Clin North Am. 2006 Sep;35(3):525-49, viii. Review.

Kissebah AH, Alfarsi S, Adams PW, Wynn V. Role of insulin resistance in adipose tissue and liver in the pathogenesis of endogenous hypertriglyceridaemia in man. Diabetologia. 1976 Dec;12(6):563-71.

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