Blood Pressure in Blacks and Calcium (BBC) and Vitamin D Study

• Status: Completed
• Trial end date: 2018-11-01
• Target enrollment: 0
• Participant gender: All

Summary

Adequate levels of vitamin D are essential for bone health at all ages but low levels of vitamin D may also negatively impact other aspects of health such as blood pressure. The investigators have previously shown that adults with African ancestry living near the equator have much higher levels of vitamin D and higher levels of blood pressure compared to adults with African ancestry living in the Chicago area. Multiple clinical trials have examined vitamin D supplementation for reducing blood pressure levels but very few studies have focused on adults with African ancestry and low vitamin D levels. In addition, most previous clinical trials have not addressed calcium intake. While vitamin D may modulate blood pressure via its actions on activation of the renin angiotensin aldosterone system, it is also possible that vitamin D mediates blood pressure via its effects on gastrointestinal calcium absorption. This pilot study is a one arm study, which will assess the safety and feasibility of supplementing 15 young adults with African ancestry and low vitamin D levels with 5,000 IU of Cholecalciferol (vitamin D3) combined with 1000 mg of elemental calcium daily for 3 months. Participants will be recruited from the Maywood Illinois and surrounding areas with flyers and brochures. The investigators will also contact previous participants of the Modeling the Epidemiologic Study/Vitamin D Ancillary Study by phone and letters. At baseline, all participants will have blood pressure measured and will provide a fasting serum specimen and a 24-hour urine collection. Calcium, parathyroid hormone level vitamin D will be measured in serum specimens and 24-hour urine calcium excretion will be measured. Repeat visits will be completed at 6 and 12 weeks of follow-up to again measure resting blood pressure and serum calcium and vitamin D levels. The overall goal is to collect pilot data to help design a larger trial of vitamin D and calcium supplementation for lowering blood pressure in young adults with African ancestry.

• Phase: Phase 2
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: Loyola University
• Treatments: Calcium, Dietary; Cholecalciferol; Ergocalciferols; Vitamin D; Vitamins

Criteria

Inclusion Criteria:

1. Age 25-45 years

2. Self-reported race/ethnicity African American

3. BMI ≥ 18 kg/m2

4. Total 25(OH)D levels < 20 ng/ml (50 nmol/L)

5. No use of vitamin D supplements within past 30 days of the screening visit

6. Able to provide written informed consent

7. Willing to take a vitamin D supplement daily for 3 months

8. Willing to return for follow-up visits to measure blood pressure and provide a blood sample to measure vitamin D and serum calcium

9. No current use of blood pressure lowering medications

10. Systolic blood pressure ≥ 100 mmHg and diastolic blood pressure ≥ 60 mmHg

Exclusion Criteria:

1. Medical history of chronic disease that affect gastrointestinal absorption of vitamin D: Crohn's disease, cystic fibrosis, and celiac disease

2. Use of medications which may affect total 25(OH)D levels: antiepileptic drugs, steroids, bile acid sequestrants, lipase inhibitors, orlistat

3. Current use of vitamin D supplements or use in past month and unwillingness to discontinue for at least 1 month prior to study enrollment

4. History of kidney stones or hypercalciuria

5. Fasting serum calcium ≥ 10.2 mg/dl

6. Average systolic blood pressure ≥ 140 mmHg

7. Average diastolic blood pressure ≥ 90 mmHg

8. Presence of type 1 diabetes mellitus, active malignancy, active thyroid disease or sarcoidosis

9. Pregnant or planning a pregnancy

10. Estimated glomerular filtration rate (based on serum creatinine level) is < 60 ml/min/1.73 m2 based on the Modification of Diet in Renal Disease formula