Effects of Niacin Therapy on Lipoprotein Composition and Function

Background:

- Niacin is a vitamin in many foods, including meats, fish, fruits, and vegetables. It is often used as a dietary supplement that causes many improvements in the body. Researchers think it can affect heart health.

Objective:

- To better understand the good effects of niacin supplementation on cholesterol, fat metabolism, and vascular health.

Eligibility:

- Adults 18 years of age and older with fasting good cholesterol (HDL-C) below 60 mg/dL.

Design:

* Participants will come to the clinic 4 times during the study.
* They will complete a 7-day food journal before visits 1 and 3.
* At visit 1, participants will be screened with questions about their diet and exercise, medical history, and any drugs and vitamins they take. Vital signs and body mass index will be measured.
* They will have a Cardio-Ankle Vascular Index (CAVI) test of the arteries. Blood pressure will be taken in the arms and legs and the heart will be monitored.
* Blood will be drawn. Participants will fast for 8 12 hours before this.
* Women will have a pregnancy test.
* Eligible participants will get a 2-week supply of niacin. They will take 2 tablets daily for one week, then 4 daily.
* Visit 2 will be 2 weeks after visit 1 and the niacin dose will be increased. Visit 3 will be 16 weeks after visit 1, and participants will stop taking niacin. Visit 4 will be 4 6 weeks after stopping niacin.
* During study visits, participants will repeat visit 1 tests.

This single center clinical pilot study will investigate the effects of niacin on blood lipids and lipoprotein composition in human subjects who are healthy. Niacin (vitamin B3 or nicotinic acid) is a common nutrient found in many foods and is currently sold over the counter as a nutritional supplement. Extended-release versions of niacin are available over the counter (e.g., Slo-Niacin) or by prescription (Niaspan) and help to alleviate symptoms of flushing associated with larger doses of the vitamin. Studies of the effects of niacin therapy on clinical lipid measures consistently indicate a shift toward a healthier lipoprotein profile with increased HDL-C and decreases in both triglyceride and LDL-C. Despite this favorable shift in lipid profile, cardiovascular outcome studies on patients receiving niacin alone or in combination with statin therapy have resulted in mixed results creating uncertainty of the value of niacin therapy. The proposed study will examine in detail the effects of niacin therapy on lipoprotein composition and function, while also tracking measures of vascular health.

Eligibility Criteria:
* INCLUSION CRITERIA:
* Males and females who are at least 18 years of age at time of enrollment.
* Subject understands the investigational nature of the study and provides written, informed consent.

EXCLUSION CRITERIA:

* Subjects taking any lipid modification therapy, including but not limited to statins, fibrates and bile acid sequestrants.
* Subjects taking fish oil or any other supplements, which in the investigator s opinion may interfere with the study.
* Subjects with acute liver disease or active peptic ulcer disease.
* Subjects with elevated uric acid levels greater than 10 mg/dL or gout
* Pregnancy or women currently breastfeeding.
* Female subjects taking hormonal contraceptives or hormone replacement therapy may be included in this study only if they have been on a stable dose for at least 3 months.
* BMI less than 18.5
* Subjects with weight that varies greater than 20% over the past 3 months.
* Subjects taking the following medications for at least six weeks, which may interfere with the study, will be excluded: BAS, antibiotics, anticoagulants, anticonvulsants, antiarrhythmic, Cyclosporine, Mycophenolate and Synthroid. Subjects with chronic diarrhea, gastric bypass or lap band procedures, ostomies, bowel motility problems, or other conditions that could affect intestinal fat absorption.
* Subjects initiating new medications or patients on multiple medications may also be excluded.
* Inability to swallow capsules
* Patients with a history of type I or type II diabetes or HbA1c greater than 6.5%.
* Volunteers may also be excluded, if in the opinion of the study investigators, they have some other condition or disorder that may adversely affect the outcome of the study or the safety of the volunteer.