Small changes in your diet do not affect your warfarin control, but significant changes can. If you plan to go on a weight loss diet make sure that you discuss this with your doctor first.
Green vegetables
Warfarin works by blocking the action of vitamin K. Green vegetables contain vitamin K and therefore a diet high in green vegetables can alter your warfarin control. However it is important to take some vitamin K in your diet, so you should not stop green vegetables completely.
Recent studies have shown that you need to eat a large amount of vegetables to have a significant effect on you warfarin control. Spinach and broccoli have high levels of vitamin K. You need to regularly eat approximately half a kilogram of broccoli or spinach daily to have a significant effect on your warfarin control.
Alcohol
Limit alcohol intake to one or two glasses of wine or beer each day. Excessive alcohol and especially binge drinking can damage the liver and increase the anticoagulant effect of warfarin. Alcohol can also inflame the lining of the stomach and increase the risk of bleeding.