Even though buckwheat has the word “wheat” as part of its name, it isn’t a wheat grain but rather a fruit seed. This is a food that, if you’re in the first stage of the diet you should treat it as a test food. Try a little of it and wait two full days, if you receive no reaction, then it should be alright to eat at least two to three times a week.
Arrowroot is a tuber which contains 23% starch. I would advise against having it during the entire first stage, and then treat it as a test food.
Tapioca is a starch, so I’d say no to that one.
Amaranth is a grain, so it’s going to give the Candida a meal.
Carob is one of those up in the air items. Treat it as a test food.