My mother is 83, has a-fib & takes coumadin (warfarin). she likes to have greek yogart on her cereal. does greek yogart have any effect on her inr count?

Unlikely significant: Greek yogurt is not a particularly rich source of vitamin k, so it's ok to eat when on coumadin (warfarin). Coumadin (warfarin) works by blocking vitamin k to thin the blood. Typically keeping with a diet that's normal for you, and allowing the physician to make adjustments in the dosage of coumadin (warfarin), is the best strategy. You shouldn't have to give up the foods you love just to be on coumadin (warfarin).