Vitamin E supplementation reverses postural stress-induced tachycardia in apparently healthy young men. - GreenMedInfo Summary

 OBJECTIVES: We sought to investigate the possible effect of chronic administration of vitamin E on haemodynamic responses to sympathetic stimulation and to test the hypothesis that chronic administration of vitamin E increases susceptibility to orthostatic intolerance. METHODS: Sympathetic stimulation was assessed by responses in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), forearm blood flow (FBF; venous occlusion plethysmography) and forearm vascular resistance (FVR) evoked by postural stress (600 head-up tilt; HUT) or cold pressor test (CPT) in 30 healthy young men before and after 4 weeks of vitamin E administration. CPT was induced by immersing a hand in water at 40 degrees C for 2 minutes. RESULTS: Administration of vitamin E reduced SBP (p<0.001), DBP (p<0.001), MAP (p<0.001), HR (p<0.001) and FVR (p<0.05) but increased FBF (p<0.01). Before vitamin E administration HUT increased HR (p<0.001). Conversely, HUT led to a decrease in HR (p<0.05) after vitamin E administration. The decreases in SBP (p<0.05) and FBF (p<0.05) with concomitant increases in DBP (p<0.001), MAP (p<0.001) and FVR (p<0.001) induced by HUT before vitamin E administration, were similar to those induced by HUT after vitamin E administration. The increases in SBP (p<0.001), DBP (p<0.001), MAP (p<0.001), HR (p<0.05), FVR (p<0.001) and a decrease in FBF (p<0.001) induced by CPT before vitamin E administration, were attenuated following vitamin E administration in these subjects. CONCLUSION: These results demonstrate that chronic administration of vitamin E significantly reversed HUT-induced tachycardia and prevented CPT-induced vascular and pressor responses. These findings suggest that vitamin E may exert cardioprotective effect presumably through enhanced cardiac vagal tone that may not be associated with poor orthostatic tolerance in young men.