Nope. I researched it a long time ago. Maybe after clot #1 which was in 2002.
Almost three years ago I was told by my hematologist that after clot #2 I should consider going on Warfarin for life. I told her I didn't want to do that. So, I took a baby aspirin every single day and then I developed clot #3 about a month ago.
Now I am a lifer. I should have listened to the doctor three years ago but I, of course, was in denial and thought NO WAY was I going to get another clot.
I played Russian roulette.
I hope you aren't thinking about taking a supplement instead of meds.

If you do a search on it in this board and on the PE board, there are several long discussions on it. I think it's a gamble if a doctor is recommending that you be on straight up anticagulants.

There have been some other threads on this ... maybe run a search to see what has been said in the past.

Personally, I'd want some sort of guarantee that the stuff works. If the only way I'll find out it *doesn't* work is by clotting again, I'm not going to go for that. Without any studies backing it, I wouldn't be on board.

That's my concern. NONE of my doctors have prescribed any prevention. The one hematologist said to call him if I get another clot. I want to know what I can do to hopefully NOT get another clot. I put myself on one aspirin a day and have changed my diet, but I have no idea what to do especially since I didn't know I had one before until it shredded and went into both lungs. He said I had blood like jelly. What does that even mean? When I had my menses it wasn't a problem, but now it supposedly is, but he offered no help or suggestions. He thinks an aspirin a day is useless but if it makes me feel better I can take it. I would gladly take low dose warfarin for life if I could but he didn't prescribe it so I am looking for alternatives!

In your situation, if it would make you feel better to take natto as a sort of preventative thing since you're not being put on anticoagulants, I personally can understand doing that. What I always worry about are people who are supposed to be on anticoagulation therapy but want to stop taking warfarin in order to take natto. I don't think that's safe. But you're wanting to take it as opposed to nothing, and I don't really see a problem with it. I don't know that it will necessarily help either, but I doubt it will hurt anything, if you're not mixing it with a lot of other stuff. For instance, since aspirin is also a blood thinner, I don't know that it would be a good idea to take both things.

There are still occasionally doctors who will recommend daily aspirin after coming of warfarin, but I don't think it's a terribly common practice because aspirin doesn't really do much to affect venous clotting. There are different clotting mechanisms much controlled by what type of vessel the clot forms in, and aspirin is more effective at preventing arterial clots. I actually was taking aspirin daily when I got my second DVT, so I tend to basically agree it doesn't do much for prevention. But apparently my body thinks clotting is a super-power, so I wouldn't necessary use my experience as the touchstone if I were you.

In fact, don't use all of us multiple-clotters here as proof that you necessarily need to have some sort of continuing care. A lot more people breeze through this site on their way to recovery, but they get better and move on with their life and don't get any more clots. Those of us here who have had two, three or more clots are the exceptions, and that's why we hang out here for years from our first clotting episode.

Some of the best things you can do for yourself is to just stay well hydrated, elevate your legs when sitting if possible and at least move them frequently if not, don't sit for hours on end. I have heard of some people taking vitamin E to try to help prevent clotting. Another thing I did, but I'm probably just weird and maybe it was just more of a psychological security blanket, but I know that celery has coumarin in it, which is the natural form of warfarin. When I wasn't on blood thinners, I ate several sticks of celery every day, much more than I would normally eat. It would be hard to eat enough to hurt yourself, unless you'd intend on making a daily smoothy out of a whole bunch of celery. Well, I still clotted, but my INR was 1.3, which is a little high for not taking medication. Maybe the celery made a difference and maybe not, but if you're looking for something to make you feel like you're doing something, without risking hurting yourself, then it's an idea.

As with any supplement, just be sure to consider the source information on the natto. I think it's kind of a tough thing to know for sure whether it helps. I mean, I'd never take it as a substitute for a known and studied anticoagulant if I needed anticoagulation, but since that's not what you're doing, I don't see a problem with you taking it. There are probably people who will sing its praises that they never clotted again because they took it, but you know, there are a lot of people who never do anything and they never clot again either, so it's hard to know for certain whether natto really did anything or not. I think if it makes you feel safer and there aren't any reasons why not to take it, then why not. But if you take it, remember that it's important to always let doctors, dentists, whoever know you take it, and realize that the reason doctors try to avoid long-term prescription of anticoagulation is because there is risk of bleeding the longer you take something like that. How much of an effect natto would have for that, I don't know.

Wish you well in deciding what to do.

Ditto what @ShilosMommy said. If you're using it as a preventative, then that's kind of a different boat than using it INSTEAD of warfarin or some other proven anticoagulant.

I'd want to find some information on how effective it is (e.g., if you take too much, are you at risk of bleeding?) and also what it interacts with, since many "natural" meds can affect other things you're taking. You might be able to check with a pharmacist on these things, since the big databases they have access to are more and more often including natural supplements as well as prescription meds.

I don't remember... do you have a diagnosed clotting disorder?

Yeah, I agree. If using as an added preventive measure while not being on warfarin, it probably doesn't hurt to try it. It's when people who are told they should be on prescribed anticoagulants and instead opt for supplements, that's probably foolish. Here's some info on supplements that may have anticoagulation affects:

http://patientblog.clotconnect.org/2013/05/01/natural-supplements/

I took a low dose aspirin every day after clot #2 thinking I would not clot again and I was wrong.
I believe you can still clot while on Warfarin too.

I just got this off the Memorial Sloan Kettering website regarding Nattokinase.

Theoretically, nattokinase can cause an existing clot to dislodge, resulting in a stroke or embolus at a distant location. Patients with a history of deep vein thrombosis should avoid of use nattokinase.

There is no robust scientific evidence that nattokinase is effective in preventing clotting. Nattokinase is a enzyme that is fibronolytic, i.e. breaks down clots. Nattokinast may be helpful, but it may only have a very limited effect. I would not replace anticoagulant treatment with nattokinase. IIt up to you whether you would like to take nattokinase or not, but it may be just waste of money due to its limited effectiveness. Baby aspirin has about 30% of the efftiveness of standard anticoagulants and may be considered if the risk of clotting is not high.

I cannot comment on whether nattokinase can actually dislodge a clot, and I would like to see the original scientifc paper suggesting that. Naturally, theroretically any fibrinolytic can dislodge clot, which may theoretically embolise. Considering how weak nattokinase is, I would guess that this is very very unlikely, but then again, I cannot really comment on it without actally seeing the original paper stating this.