>> found a product online .. Jarrow Formulas NattoMax
I don't think this supplement would work.. it looks to be just the nattokinase enzyme, and not the B Subtilis microbe. So nope, this won't work at all I'm afraid
The easiest way to get it is to find an Asian grocer that stocks some japanese stuff. Do a search on google maps in your area and call some of them.
Baruch mentioned wanting to try isolating the B Subtilis from the soybean by soaking the beans in water. A brief soak I suppose as otherwise starch will slowly seep out.
I only ate one or two teaspoons at a time when I started. I didn't have any reaction at the time! And I was definitely starch sensitive still, so I wouldn't be overly worried.
The most potent way to get the B Subtilis is to make your own at home, that way it will be fresh and very active. I bought some Nattomoto starter culture off eBay and I intend to try making my own at home in an electric yoghurt maker (well.. actually I have tried already failed, but I am not giving up yet). You can also use frozen Natto from the asian grocer as a starter.
Hope some more people will be game to try Natto as an experiment