Interaction of dietary factors with oral anticoagulants: review and applications.

This article reviews the published original sources of information on interactions of oral anticoagulants with dietary factors, points out deficiencies in our knowledge of these interactions, and suggests applications for this information in the clinical setting. As with many drug-nutrient interactions, the original references include a few experimental studies and many case reports. Deciding which interactions of oral anticoagulants with dietary factors are clinically relevant and determining the appropriate dietary prescription concerning each interaction involves, in most cases, an educated opinion rather than a conclusion based on extensive research. Enough information exists on the vitamin K content of foods and the quantity of vitamin K that alters coagulation status from the therapeutic range to provide the patient with advice concerning a group of foods to avoid and a group of foods to limit to one serving per day. With respect to other dietary factors that may interact with oral anticoagulants, the patient should be cautioned concerning supplements of vitamins A, E, and C and alcohol used chronically or ingested in large quantities.