Objective: To determine the relationship between serum vitamin D levels and known cardiometabolic risk factors among healthy Icelandic children as well as study these connections independent of body mass index (BMI).

Methods: We assessed the relationship between serum 25-hydroxyvitamin D, adiposity measured as BMI and 7 cardiometabolic risk factors (high blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, blood glucose and serum insulin). Subjects were 7-year old school children in six randomly selected elementary schools in Reykjavik, Iceland, in the autumn of 2006.

Results: Vitamin D was measured amongst 159 children. 35 (22%) were lower than 37,5 nmol/L, 70 (44%) between 37,5-50,0 nmol/L and 55 (34%) over 50 nmol/L. Deficiency was defined as lower than 37,5 nmol/L. No difference was between girls or boys, girls (n:85 = 44,2nmol/L), boys (n:74 = 46,9nmol/L), (p= 0,052). Deficient children had higher BMI (p=0.052), lower HDL (p=0.044) and higher HbA1c (p=0.015), and insulin (p=0.014) than those who had vitamin D higher than 50 nmol/L. Significant correlation was between low levels of vitamin D and high levels of serum insulin (p=0,014) and high levels of HbA1c (p =0,015), independent of BMI.

Conclusion: Vitamin D deficiency has been associated with the development of cardiovascular disease. It is important to explore the connection between known risk factors and vitamin D and treat those who are deficient of it, especially children and young adults. It is possible that vitamin D deficiency has an effect on cardiovascular risk early in life through insulin resistance and altered blood sugar control. It is important to follow guidelines for giving vitamin D to children, as the result showed that 2/3 of the children were under 50 nmol/L.

Figure I Correlation between vitamin D levels and HbA1c and serum insulin.

Table I Mean values of some cardiovascular risk factors according to vitamin D levels.

Table II Mean values of some cardiovascular risk factors among children with normal and deficient/insufficency Vitamin D.

Table III Correlations of vitamin D with various cardiovascular risk factors.