Background: Recently, vitamin D has received an enormous attention, primarily at the public health level due to its numerous biological effects. It has been suggested that vitamin D deficiency may adversely affect blood pressure and the cardiovascular system. The aim of this project was to determine the possible effects and association between vitamin D intake, blood pressure, glucocorticoids and CVD risk factors.
Methods: Two pilot studies have been carried out; one using short-duration repeated measure (n=20) and the second was a randomised parallel controlled design (n=38). Healthy volunteers from Queen Margaret University were recruited. Each participant was asked to consume 20 μg (800 IU/day) of vitamin D3 supplement per day for 14 days (1st study), and vitamin D or placebo for 28 days (2nd study). Three readings of systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse wave velocity (PWV) were recorded at baseline and at the end of the intervention. Blood (glucose and lipids), saliva and 24h urine (glucocorticoids) samples were obtained. Diet dairies and lifestyle questionnaires were also monitored through out the study.
Results: Vitamin D intake increased significantly in both studies (P<0.001) and thus indicating compliance. Mean PWV showed a significant decrease of 0.74 m/s (P=0.017), with a negative correlation with vitamin D intake (r=−0.43). There was also a significant decrease in mean SBP (115.3±13.1110.9±10.8, P=0.035) and DBP (73.6±10.669.8±9.1, P=0.04). There was no significant change in BMI between baseline and final measurements (P=0.527). No significant differences were found between the groups in total, LDL cholesterol, triglycerides and glucose except HDL increased following 4 weeks of D intake; from 0.92±0.121.24±0.35 mmole/l (P=0.025). There was no effect on salivary cortisol but cortisone increased (0900 h: 7.33±2.69.98±5.3 nM, P=0.04). Urinary free cortisol/cortisone ratio was reduced (1.91±0.751.22±0.53, P=0.015).
Conclusion: The results suggest that moderate intake of vitamin D can influence salivary and urinary glucocorticoids, attenuate BP, improve cardiovascular markers and might be beneficial to prevent contemporary diseases. Further studies to elucidate the effects of the sunshine vitamin, particularly in relation to CVD risk factors would be justified.