A new study published in the Journal of Clinical Endocrinology & Metabolism found that low vitamin D levels during childhood are associated with subclinical atherosclerosis in adulthood.
Atherosclerosis refers to the buildup of fats, cholesterol, and other substances on the walls of your arteries. Over time, this process slowly blocks arteries and reduces blood flow, which increases the risk for heart attack, stroke, and even death.
Carotid intima-media thickness (CIMT) is the measurement of the two innermost layers of the carotid artery wall. Increased CIMT usually indicates an increased buildup has occurred on the carotid artery, and is therefore used to detect atherosclerosis.
Research has shown that low vitamin D status may contribute to the presence of atherosclerosis through several different mechanisms. Activated vitamin D decreases vascular proliferation, the development of new blood vessels. Vascular proliferation leads to the arteries hardening. Activated vitamin D also inhibits vascular calcification. Additionally, some studies have shown that vitamin D reduces blood pressure.
Epidemiological studies have provided strong evidence for this relationship by showing that low vitamin D status is linked to higher cardiovascular risk. Though, prospective cohorts and randomized controlled trials of adults have found conflicting results. This has led researchers to hypothesize that the effects of vitamin D on cardiovascular health may take place earlier in life.
In the current prospective cohort, researchers wanted to determine whether vitamin D status in childhood was associated with CIMT in adulthood. In order to do this, they followed 2,148 participants from the Cardiovascular Risk in Young Finns Study for 27 years. The cohort was created to better understand precursors of atherosclerosis of Finnish children and adolescents.
In 1980, baseline measurements and surveys were taken of participants, ages 3 to 18 years. Participants were re-examined in 2007, at ages 30 to 45 years.
Researchers collected data on vitamin D status and multiple potential confounding factors in childhood and adulthood, such as anthropometrics, blood pressure, diet, smoking habits, and physical activity. They then compared vitamin D status during childhood and adulthood to CIMT during adulthood.
Did vitamin D status during childhood or adulthood affect the risk of increased CIMT? Here is what they found:
- There was a significant correlation between baseline and follow-up vitamin D levels (p < 0.001).
- Study subjects with vitamin D levels in the lowest quartile in childhood had a significantly higher prevalence of high-risk IMT as adults with a prevalence of 21.9% vs. 12.7%, respectively (p < 0.01).
- After adjusting for age, sex, and childhood risk factors, childhood vitamin D status was inversely associated with CIMT in adulthood among females (p = 0.03), but not among males (p = 0.88).
- Adult vitamin D status was not significantly associated with high-risk IMT in adults (p = 0.10).
The researchers concluded,
“We found that low levels of 25-OH vitamin D in childhood, but not adulthood, were associated with subclinical atherosclerosis in adults.”
The continued by stating,
“From a clinical perspective, our findings suggest that suboptimal vitamin D levels in childhood should be considered a possible risk factor for adult cardiovascular disease, although the therapeutic implications are unknown.”
The study had several major strengths. The large randomized sample population permits more powerful results. Also, the participants were followed for a long duration. Lastly, the researchers collected extensive data on potential confounding factors.
There were also important limitations to note. The study population was comprised of young adults, so they were unable to associate cardiovascular events with vitamin D status. In addition, the study only included Finnish participants, which limits the generalizability of the results.
Juonala M., et al. Childhood 25-OH Vitamin D Levels and Carotid Intima-Media Thickness in Adulthood: The Cardiovascular Risk in Young Finns Study Markus. Journal of Clinical Endocrinology & Metabolism, 2015.