Vitamin D and Carotid Artery Distensibility
Presented by Geetha Raghuveer, MD, MPH
Retrospective and observational studies have shown vitamin D deficiency in adults to be associated with hypertension, diabetes, atherosclerosis, myocardial infarction, congestive heart failure, stroke and decreased kidney function. Even among adolescents, deficient vitamin D states are associated with hypertension, hyperglycemia and metabolic syndrome. However, the literature on the effects of vitamin D on cardiovasculature in children has been lacking.
“Recent literature has confirmed that vitamin D deficiency is prevalent in children particularly in children who are obese,” says Children’s Mercy cardiologist Geetha Raghuveer, MD, Associate Professor of Pediatrics at UMKC School of Medicine. “Almost every child who is obese has vitamin D deficiency. I was interested to see if this has any effect on their vasculature.”
At the American Heart Association Scientific Session in November 2011, Dr. Raghuveer and her colleagues presented findings from a retrospective study of vitamin D deficiency in children at risk for cardiovascular disease.
Dr. Raghuveer evaluated 74 children ages 6-22 in the Children’s Mercy Hospital Preventive Cardiology Clinic. Demographic and anthropometric data including age, sex, race, weight, height, and BMI were gathered. Family history of premature heart disease and history of tobacco smoke exposure were ascertained via an interview. Blood pressure, fasting lipid profile, insulin and serum 25-hydroxyvitamin D3 data was collected.
Vitamin D was used as a continuous predictor variable and in addition categorized into two levels (Insufficient - < 20 ng/ml, Sufficient - >20 ng/mL) to examine its relationship with the carotid artery distensibility index (a test of vascular function) and Carotid Intima Media Thickness (CIMT) – a marker of atherosclerosis.
Seven modifiable atherosclerosis-promoting risk factors were also analyzed as predictor variables with respect to their relationship with the carotid artery distensibility index and CIMT:
- Obesity - BMI ≥ 95th percentile for age and sex
- Systolic Blood Pressure ≥ 95th percentile for age, sex, and height
- Total cholesterol ≥ 170 mg/dL
- Triglycerides ≥ 100 mg/dL
- High Density Lipoprotein Cholesterol ≤ 45 mg/dL
- Insulin ≥ 18 uIU/mL
- History of exposure to tobacco smoke
“We found that those kids who had vitamin D levels which were much lower had additional problems with their carotid arteries. We did not see increased thickening of the inner lining of the carotid arteries as we thought we would see, but what we saw was more interesting,” says Raghuveer. “Those who had a serum 25 hydroxyvitamin D3 level < 20 ng/ml had a decrease in the distensibility index suggesting poor function of the artery, even after adjustment for other atherosclerosis promoting factors.”
This is the first study of children that correlates low vitamin D levels and blood vessel function. Additional studies involving larger sample sizes are necessary.
Dr. Raghuveer is continuing to follow these children to see if vitamin D supplementation leads to restored distensibility over time. “Hopefully this is early change which can be reversed with supplementation,” says Dr. Raghuveer.