I don't know exactly (percentagewise) how much diet affects your INR vs. activity/exercise level vs. other Rxes and OTCs and herbals vs. illness/physical condition/age.
Warfarin (Coumadin) is a slow-loading drug. It takes about 72 hours for a dosage change to be reflected in the INR. Therefore, it stands to reason that if you pig out one day on broccoli (broccoli/spinach omlette for breakfast, beef-broccoli stir-fry for lunch and have broccoli/cheese/rice side dish at dinner) but go back to a normal eating pattern, it shouldn't affect you all that much.
However, if you tend to be a fairly consistent person -- which most people probably are, you would be OK. We're not talking holidays and special occasions.
Alcohol can be dehydrating, has empty calories and can cause you to stumble, fall if you have too much. In the right amount, it's OK and can be heart-healthy. I do drink on occasion -- a margarita or two, martini, glass of wine, but that's all.
My INR has been fairly consistent since late April, when I got my 2nd INR monitor (INRatio). I tested yesterday at work -- while multi-tasking on the computer and answering phone calls!!! -- and it was 3.0. Two weeks ago it was 3.3; three weeks prior to that it was 3.1. My INRs have been 2.7-3.5 in the last 6 months.
As far as warfaring being "complicated," it can present challenges for some situations (surgeries, for example), but in everyday life it does not.
That is, unless you don't understand anticoagulation therapy management. And there are some medical professionals out there like that. They have other fish to fry, so to speak, and just don't have time or inclination or enough warfarin patients in their practice to really think and want to learn how to handle warfarin.
Marsha (7-28-50), MVP 1990/MVR (St. Jude) & ASD repair 6/24/03 Baylor University Medical Center, Dallas Texas. Hometesting since 11/03, first with ProTime 3, now with INRatio.
John (3-13-46), MV repair 5/10/07, Dallas Presbyterian, port-access incision, Dr. William Ryan. Chordae ruptured 12/05 in car crash.