Vitamin D Status and Its Correlation with Heart Rate Variability Among Healthy Female Medical Students at King Abdulaziz University: A Cross Sectional Study

Presentation Number: SUN 350
Date of Presentation: April 2nd, 2017

Lojine Diaaldin Ayoub*, Hanan A Al Kadi and Azra Kirmani
King Abdulaziz University, Jeddah, Saudi Arabia



Vitamin D deficiency is a global health problem and is highly prevalent among the Saudi population. A growing body of evidence indicates an association between vitamin D deficiency and risk of cardiovascular disease (CVD). Heart rate variability (HRV) is a non-invasive technique that evaluates cardiac autonomic function which is a major determinant of cardiovascular health. High HRV is a sign of normally functioning autonomic nervous system (ANS). On the other hand, low HRV is not only indicative of CVD, but also a predictor of an impending one. Limited data is available on the relationship between vitamin D deficiency and HRV and none exists among the Saudi population. Therefore, this study was conducted to examine the association between vitamin D status and HRV in apparently normal female medical students at King Abdulaziz University (KAU) in Jeddah, Saudi Arabia.


This cross-sectional study was conducted at the Faculty of Medicine, KAU. A total of 124 female students participated in the study. After completing a self- administered questionnaire, anthropometric measurements of all the subjects were obtained. HRV was recorded after five minutes rest in the supine position using ML870 power lab machine. Blood was obtained for the determination of serum levels of 25-hydroxyvitamin D3 (25[OH]D), parathyroid hormone (PTH), calcium, phosphate and magnesium. Serum levels of 25(OH)D were determined using a chemiluminescent immunoassay. Informed consent was obtained from all participants and the study was approved by the ethics committee at KAU hospital.


The mean age of the study subjects was 21.7± SD 1.1 and the mean 25 (OH) D levels was 31.2 nmol/L ± SD 16.9. Almost 86 % of the participants were vitamin D deficient (defined as 25(OH)D level <50 nmol/L) and 53% had 25(OH)D levels < 30 nmol/L. Seventy-two (72%) of the participants with 25(OH)D<30 nmol/L had “Root mean Square of the Successive R-R interval difference” (RMSSD) values (an index of parasympathetic activity) below the 25th percentile compared to 28% with 25(OH)D ≥30 nmol/L (chi-square, P=0.049). Regression analysis showed that 25(OH)D level was independently and negatively associated with “Low Frequency Power normalized” (LFnu) (an index of sympathetic activity) (B=-0.175, P<0.028).


Our findings suggest that vitamin D deficiency is associated with low HRV, a predictor of CVD risk. Larger community based studies are needed to confirm these findings. Early identification of vitamin D deficiency coupled with appropriate corrective measures may reduce the risk of CVD in otherwise healthy subjects. Demonstrating an increase in HRV following improved vitamin D status will substantiate the conclusions of this study.


Nothing to Disclose: LDA, HAA, AK