Hi! I have an irregular heartbeat my INR was 1.4, I am on I was on 4.5 mg of warfrin, my doctor changed the dose to 5mg, could this be my diet?

Vit k. Vitamin k is in dark green leafy vegetables and a lot of other foods. A balanced intake of vitamin k by eating a balanced diet and avoiding large fluctuations can help. Work with your doctor or your anticoagulation clinic for guidance.
Yes. The blood thinning effect of Coumadin (warfarin) is dependent on vitamin k which is in the diet. Medications including many otc meds can also alter the inr. There are now 3 alternative medications that do not exert there effects through vitamin k dependent clotting factors.