A new study published in Journal of Clinical Laboratory Analyses found that low vitamin D levels were associated with aortic intima-media thickness and C-reactive protein, both markers for atherosclerosis.
Atherosclerosis is the hardening and thickening of the artery walls. It is the most common cause of heart disease, which is the number one killer in America.
All arteries, including the aorta, are made up of three layers: the adventitia, the media, and the intima. The intima is the layer that is in direct contact with the blood, whereas the media surrounds the intima and is made up of mostly connective and muscle tissue. The adventitia is the outer-most layer of the arteries.
The intima media thickness (IMT) is a measurement of the two innermost layers of the arterial wall. It can be measured in various ways. One measurement is a trans-esophageal echocardiography, which creates a detailed picture of the heart and the arteries that lead to and from it (such as the aorta). A thicker IMT is associated with early stage atherosclerosis.
Previous research shows that vitamin D may help atherosclerosis by reducing inflammation and arterial stiffness. However, no research has looked at the relationship between vitamin D levels and aortic IMT in people without atherosclerosis.
Recently, researchers enrolled 117 patients who underwent trans-esophageal echocardiography to evaluate the relationship between vitamin D status and aortic IMT. All patients had heart disease, but did not have atherosclerosis.
After the patients had their vitamin D levels measured, they were divided into three groups. The groups were categorized by their vitamin D status, defined as either vitamin D-deficient, with levels lower than 20 ng/ml, vitamin D-insufficient, with levels lower than 30 ng/ml, or vitamin D-sufficient, with levels above 30 ng/ml.
The researchers also looked at the patients’ C-reactive protein (CRP), which can be measured to predict heart disease. The researchers then combined data on the patients’ vitamin D statuses, CRP levels, and aortic IMT to conduct their analyses.
This is what they found:
- Overall, 75.2% of the patients had vitamin D levels lower than 30 ng/ml.
- The vitamin D deficiency group had the highest CRP and aortic IMT values (P < 0.05).
- The vitamin D insufficiency group had higher CRP and aortic IMT values compared to the vitamin D sufficiency group (P < 0.05).
- Low vitamin D levels were significantly associated with higher CRP and higher aortic IMT values (P < 0.001).
The researchers stated,
“In conclusion, low vitamin D is independently associated with higher thoracic aortic IMT as well as hs-CRP in patients without clinical manifestation of atherosclerotic cardiovascular disease. Low vitamin D may play a role in both pathogenesis of subclinical thoracic atherosclerosis and chronic inflammatory process.”
The researchers recruited patients with different cardiovascular conditions and disease severity, meaning that we can’t say for certain if vitamin D generally relates to aortic IMT. Furthermore, the observational design prevents the ability to say that low vitamin D levels cause increased IMT.
The additional evidence presented in this study confirms previous associations observed in research between vitamin D and atherosclerosis. Further studies need to address the question of whether vitamin D supplementation before or after the development of atherosclerosis reduces IMT and helps manage the disease.
Kalkan G. et al. Serum 25-Hydroxyvitamin D Level and Aortic Intima-Media Thickness in Patients Without Clinical Manifestation of Atherosclerotic Cardiovascular Disease. Journal of Clinical Laboratory Analysis, 2014.