Sunweavers: Supporting Native American Women's Vitamin D Research

Cardiovascular disease (CVD) and diabetes occur commonly among Native Americans (NA), and are leading causes of death among northern US NAs. Moreover, low vitamin D status occurs commonly in this same population. An increasing amount of evidence indicates a correlation between low vitamin D status and CVD and diabetes by contributing to a heightened pro-inflammatory environment within the endothelial lining of blood vessels leading to atherosclerotic disease, and an impaired sensitivity to insulin leading to diabetes. Our fundamental hypothesis is that low vitamin D status is a risk factor for CVD by causing a proinflammatory milieu, thereby leading to endothelial dysfunction. Additionally, the investigators hypothesize that vitamin D supplementation will reduce inflammation, thereby restoring endothelial function and ultimately reducing CVD risk.

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases; Vitamin D Deficiency
• Intervention / Treatment: Dietary supplement: Vitamin D3

Detailed Description

Low vitamin D status is endemic due to 21st century lifestyle, which limits sun exposure, and inadequate dietary intake. An increasing body of data relates low vitamin D status to increased risk for non-musculoskeletal morbidities including, most notably, cardiovascular disease (CVD) and type II diabetes mellitus (T2DM). CVD, for which T2DM is a major risk factor, causes over one-third of all deaths in the US. Moreover, American Indians (AI) and Alaskan Natives (AN) are 20% more likely to develop CVD and 2.2 times more likely to develop DM than non-Hispanic whites. In fact, AI of the Great Lakes Region (Bemidji Area) have the third highest DM rate in the nation, an age-adjusted DM mortality rate almost three-fold higher than the all-race mortality, and the highest rates of CVD among AI nationally. In this population, where CVD and DM are two of the top four causes of death, our preliminary work finds low vitamin D status commonplace.

As low vitamin D status, CVD and T2DM are epidemic among AI, the investigators hypothesize that low vitamin D is causally related to CVD and T2DM by establishing a pro-inflammatory milieu, which in turn predisposes to CVD and T2DM. As such, vitamin D supplementation should reduce markers of inflammation and thereby ultimately reduce risk for CVD and T2DM. This work will explore this possibility by evaluating the effect of vitamin D status on endothelial function (measured by arterial reactivity), plasma biomarkers of inflammation and glucose homeostasis in 100 postmenopausal AI women. Subjects will receive vitamin D3, either 400 or 2,500 IU, daily for six months. The investigators will define the effects of vitamin D status, and subsequent response to supplementation, on endothelial function, arterial stiffness (flow-mediated vasodilation (FMD) of the brachial artery, and carotid to femoral pulse wave velocity (PWV)), plasma markers of inflammation and glucose homeostasis. All study participants will have fasting laboratory and noninvasive vascular ultrasound studies performed at baseline and following three and six months of study. Plasma concentration of pro-inflammatory cytokines will be measured as secondary outcome variables. Fasting blood glucose, insulin and the adipocytokines leptin and adiponectin, will be measured as exploratory outcomes for potential future studies.

• Study Type: Interventional
• Enrollment (Actual): 99
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Bowler, Wisconsin, United States, 54416
      • Stockbridge-Munsee Nation
    • Lac du Flambeau, Wisconsin, United States, 54538
      • Bad River Nation
    • Madison, Wisconsin, United States, 53705
      • University of Wisconsin Osteoporosis Clinical Research Program

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 55 years to 75 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Ambulatory, community dwelling AI woman
• Postmenopausal up to age 75 years; for women below age 55, postmenopausal status must be confirmed by documentation of serum FSH>30 IU/L and estradiol < 20 pg/ml unless a bilateral oophorectomy is documented.

Exclusion Criteria:

• Serum 25(OH)D < 10 or > 60 ng/ml.
• Known CVD (history of MI, coronary artery bypass graft surgery, percutaneous coronary intervention, stroke, transient ischemic attack, peripheral arterial disease with claudication).
• Uncontrolled thyroid disease (thyroid stimulating hormone level outside of normal range).
• Change in dose of lipid lowering medications within the preceding six weeks.
• Mastectomy of the right breast
• Non-English speaking, illiterate, impaired decision making.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: PREVENTION
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: DOUBLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: 400 IU Vitamin D3	Dietary supplement: Vitamin D3; The vitamin D3 will be taken daily.
EXPERIMENTAL: 2500 IU Vitamin D3	Dietary supplement: Vitamin D3; The vitamin D3 will be taken daily.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in markers of endothelial function	This will be determined by evaluating CRP and lipid panel	Baseline visit, 3 month visit and 6 month visit.
Change in arterial stiffness with vitamin D3 supplementation	Change in arterial stiffness will be evaluated with radial tonometry.	one year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Plasma concentration of pro-inflammatory cytokines	This will be evaluated by assessing TNF alpha, IL6, VCAM and ICAM	Baseline visit, 3 month visit, and 6 month visit.

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison

Publications and helpful links

General Publications

• Gepner AD, Haller IV, Krueger DC, Korcarz CE, Binkley N, Stein JH. A randomized controlled trial of the effects of vitamin D supplementation on arterial stiffness and aortic blood pressure in Native American women. Atherosclerosis. 2015 Jun;240(2):526-8. doi: 10.1016/j.atherosclerosis.2015.04.795. Epub 2015 Apr 25.

Study record dates

Study Major Dates

• Study Start: July 1, 2011
• Primary Completion (ACTUAL): January 1, 2014
• Study Completion (ACTUAL): April 1, 2014

Study Registration Dates

• First Submitted: November 29, 2011
• First Submitted That Met QC Criteria: December 8, 2011
• First Posted (ESTIMATE): December 12, 2011

Study Record Updates

• Last Update Posted (ESTIMATE): November 20, 2014
• Last Update Submitted That Met QC Criteria: November 19, 2014
• Last Verified: November 1, 2014

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Avitaminosis; Deficiency Diseases; Malnutrition; Cardiovascular Diseases; Vitamin D Deficiency; Physiological Effects of Drugs; Micronutrients; Vitamins; Bone Density Conservation Agents; Calcium-Regulating Hormones and Agents; Vitamin D; Cholecalciferol
• Other Study ID Numbers: H-2010-0118