He just needs to eat a diet that is reasonably consistent in its levels of vitamin K. If he is getting his INR
checked at least once a month, and the INR
is relatively stable, then his diet is appropriate, as far as his taking Coumadin is concerned. The INR will show it, if there is a problem with his diet. He has been on Coumadin since 2002, so if there have been no major problems with his INR so far, then I wouldn't worry about it.