“Can high fluid intake prevent cerebral and myocardial infarction?” Systematic Review

Objectives: We performed a systematic review about whether high fluid intake can prevent cerebral and myocardial infarction. Materials and Methods: Previously published papers were searched for in PubMed using the combined terms of dehydration, hydration, water intake, fluid intake, cerebral infarction, cerebrovascular disease, apoplexy, myocardial infarction, angina pectoris, ischemic heart disease, blood viscosity and hemorheology. Results: Of 611 papers searched, twenty-two were selected. There was one prospective randomized study, four prospective non-randomized studies, eight epidemiologic (cohort or case-control) studies and nine retrospective descriptive studies, presenting the following points. Dehydration, which increases blood viscosity, is one of the causes of cerebral or myocardial infarction. Important factors other than dehydration can cause an increase in viscosity. Drinking water during the night can protect an increase in blood viscosity but there has been no evidence that drinking excessive amount of water prevents cerebral infarction. There was one report that the risk of myocardial infarction was lower in people drinking more than 5 glasses of water than those drinking less than 2. Conclusion: Since cerebral and myocardial infarction are primarily caused by atherosclerosis and atheroma plaque, it is essential to adjust life style for prophylaxis. There has been no direct evidence that decrease in viscosity due to high fluid intake can prevent cerebral infarction. Further studies regarding the relationship between fluid intake and ischemic diseases, and the appropriate fluid intake for the elderly to improve their QoL are needed.