Sorry about previous - I sent the mail without writing it.  It must be late
Sunday night!  Anyway the MD is telling her not to take her Blessed Thistle
"leafy green" because of its vitamin K content which might cause her
prothrombin times to fluctuate.  Any vitamin K containing food can do this:
broccoli, kale, spinach, etc. Vitamins A and E also interact with Coumadin.
 Also, some herbs contain a related substance, coumarin - tonka beans,
melilot, woodruff.  Though I cannot find any references on the vitamin K
content of Blessed Thistle it is probably safe to assume it contains some
vitamin K.  How much is she ingesting?

While it used to be recommended that those on Coumadin restrict their leafy
green intake, recommendations now are to keep intake down to about 1 cup raw
or 1/2 cup cooked per day.  The point is to eat them in your usual pattern,
and not to eat 6 cups of turnip greens (for example) all at once.  Her
prothrombin times will be checked regularly and Coumadin dose adjusted to her
individual diet.

A couple of references:
Harris JE, Interaction of dietary factors with oral anticoagulants: Review
and applications. J Am Diet Assoc. 1995;95:580-584.

Booth SL, et al. Tea and coffee brews are not dietary sources of vitamin K-1
(phylloquinone) J Am Diet Assoc. 1995;95:82-83.

Sanna James, M.S., R.D.
- also a breastfeeding mom on Coumadin