Abstract

IMPACT OF GREEN LEAFY VEGETABLES ON WARFARIN THERAPY: A REVIEW OF DIETARY VITAMIN K INTERACTIONS

S. Kumar, D. T. Bappanad* and A. R. Shabaraya*

Abstract

A widely used anticoagulant Warfarin is commonly prescribed for prevention and treatment of thromboembolic disorders. The mechanism works by inhibiting the vitamin K epoxide reductase complex, thereby reducing the synthesis of clotting factors II, VII, IX, and X. A common belief is that dietary vitamin K intake could counteract the anticoagulant effect of vitamin K antagonists. Hence, patients have been discouraged from consuming vitamin-K-rich foods, such as green leafy vegetables. Since green leafy vegetables—such as spinach, kale, and broccoli—are rich sources of vitamin K, there has been a long-standing concern that their consumption may counteract warfarin’s anticoagulant effects by lowering INR levels. However, emerging evidence suggests that the primary concern is not the intake of vitamin K-rich foods itself, but rather inconsistencies in dietary vitamin K consumption. Studies indicate that maintaining a stable intake of vitamin K supports INR stability and improves anticoagulation control. The findings suggest patients with highly variable vitamin K intake may experience more significant fluctuations in INR, whereas those with consistent intake demonstrate improved anti-coagulation stability. In clinical practice, a balanced and informed approach to diet is essential for patients on warfarin therapy. Complete avoidance of green leafy vegetables is unnecessary; instead, a consistent and moderate intake of vitamin K is recommended to maintain stable INR levels.

Keywords: Warfarin, vitamin K, dietary interactions, green leafy vegetables, anticoagulation, INR.