Many (and I mean 'many') of the charts that tell you how much Vit K is in green tea are based on a mis-understanding/mis-reading of the actual amount of Vit K in green tea. I've researched Vit K extensively. (grin)

Green tea has zero Vit K, just as black tea does. It won't affect your INR if a person drinks it in 'moderation'. I don't know what other 'things' in green tea might affect your INR. Only one person here has reported that green tea messes her INR up a 'lot'. Maybe the caffeine? Dunno.

Moderation.

Personally, if I make any major change to my diet (and drinking a lot of green tea suddenly would be a major change, I think), I just make a point to check my INR within a week or so, just to play it safe. I mean, everyone reacts a little differently to things, so even if everyone says it won't affect my INR, I usually check to be sure.

No harm in checking sooner, just to put your mind at ease.

I'm not planning on starting to drink a gallon a day or anything. Maybe a cup a day and then go up to 2 or 3 after a couple weeks. I already eat a lot of vitamin K foods pretty often so my dose kind of accounts for that already.

Oh, did Meg mention drinking a 'lot' of green tea? Then that doesn't come under 'moderation'.

But perhaps she should answer.

The chemical components of green tea might offer some insight as to why some people might have their INR changed by green tea.

"Chemical Components

Green tea is claimed to have possible health benefits. The healthful properties of green tea are largely attributed to their unfermented leaves and high concentration of polyphenols, chemicals with powerful antioxidant properties, which also gives it is slight bitter taste. Polyphenols antioxidant effects are said to be greater than that of vitamin Cs. Antioxidants work to neutralize free radicals, which are damaging compunds that are natural produced in the body or by environmental toxins, and prevents their damaging actions.

Polyphenols found in teas are classified as catechins. Green tea has six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). Amongst the six primary catechin compounds, apigallocatechin gallate (EGCG) is the most active and most studied polyphenol component in green tea. Green tea also contains alkaloids such as caffeine, theobromine, and theophylline, which gives green tea its stimulant effects. (http://www.umm.edu/altmed/articles/green-tea-000255.htm)"

http://healthpsych.psy.vanderbilt.edu/Web2007/GreenTea.htm

Ah Ha! So maybe it isn't the Vit K in green tea that's the culprit but the antioxidants. (THAT'S JUST SURMISE, NOT FACT!)

But:

"Foods containing antioxidants such as fruits and vegetables are generally healthy for you, but boosting antioxidant intake with supplements such as green tea should not be undertaken while on Coumadin."

Livestrong would not be my choice for the best medical advice, but it isn't bad either.

So, since antioxidants live in most fruits and veggies----- I will 'surmise' that moderation is the key----- for antioxidants.

There are green tea pills which almost certainly will give a person too much Vit K, antioxidants and caffeine. (grin)

Moderation.

I said regularly, not a lot. I consider a cup or two a day regularly but not a lot. Most people would consider a glass of wine a day to be in moderation, I would assume tea would be at least the same.

Meg---- thanks for answering. Unless your doctor feels you shouldn't (he may know things that we don't know) I wouldn't worry .

She may just encourage a sooner INR check.

i drink a couple of cups of green or white tea a day with no ill effects :-)

And I go in spurts where I drink it a lot and then not at all, completely inconsistent and it has no effect on my INR. If concerned, just check your INR after you start drinking it regularly and see what happens.

It doesn't affect my inr.

Because vit. K is fat soluble and not water soluble, not much of the vit K found in green tea leaves makes it into the water when you brew the tea.

I've only seen one reference to a person's inr going up after drinking large amounts of green tea (1 gal a day). It may be that something else in the tea caused the increase.

If you feel uncomfortable, you can always go in for a check sooner. Of course, you wouldn't know for sure that any changes in your levels came from the green tea.

Glad you haven't eliminated vit k from your diet. It is very important for your health.

I looked into drinking Matcha Green Tea because of it's health benefits, and discovered it likely had significant levels of vitK....but could never find a definitive amount. Might want to stay away from this kind. There's lots of other kinds out there.

I like your idea of just trying it and having your INRs tested right away to see if it made a difference- best way to know.