Honestly, for me, because my thyroid is super sensitive to things like that, moderation for me would be a couple times a week. In practice, I’ll have a cuppa ti (as they say in ol’ Alba) once in a blue moon. I avoid soy for the same reasons. But lots (most??) of folks have no problems whatsoever. I’m pretty sure there are “low fluoride” teas on the market, but I’ve never had any.
Well, I obviously don’t have anything wrong with my thryroid, cause they did tests on that when I was in the hospital; in fact I asked specifically about that. SirKit’s sister had told me that a friend of hers had gone to the hospital with shortness of breath and heart palpitations, and it turned out to be what they described as a ‘thyroid storm’. They removed her thyroid, and she’s taking some drug every day, from now on. I don’t mind black teas, but I like the antioxidant properties of the greens.