Pharmaco-nutrient interactions - a systematic review of zinc and antihypertensive therapy

Background: Antihypertensive medicines are to known to cause diverse disturbances to electrolyte homeostasis; however, their potential to affect zinc is less well known. The primary aim was to explore whether antihypertensive medicines have the potential to affect zinc status. Methods: A review of electronic databases was undertaken. Full-length English language articles describing clinical trials involving antihypertensive medicines and reporting on zinc measurements were reviewed. Results: Eight eligible studies were identified which involved the use of ACE inhibitors, thiazide diuretics, beta blockers, or ARB drugs of which five included a control group Studies used urinary zinc excretion, plasma zinc levels or erythrocyte zinc as key measures of zinc status. Studies reported increased urinary zinc losses for captopril (from 50mg/day), enalapril (20mg/day), losartan (50mg/day), losartan (50mg/day) together with hydrochlorothiazide (12.5mg/day), captopril (75mg/day) together with frusemide (40mg/day) and stand-alone hydrochlorothiazide (25mg/day). Serum levels of zinc decreased with captopril (50-150mg/day), verapamil (240mg/day), atenolol (50-150mg/day) and the combination of losartan (50mg/day) and hydrochlorothiazide (12.5mg/day), eryrthrocyte levels decreased with use of valsartan (80mg/day) and in some studies for captopril, but not for metoprolol (100mg/day), atenolol (50-150mg/day), verapamil (240mg/day), doxazosin (4mg/day) or amlodipine 10mg/day). Major limitations were that most studies were small and did not report on dietary zinc intake. Conclusion: The available evidence suggests that use of ACE inhibitors and angiotensin 2 receptor antagonists or thiazide diuretics have the potential to reduce zinc levels in hypertensive patients. Additional research using larger participant numbers and accounting for dietary zinc intakes are required.