I've read that warning before. I used Tom's of Maine (the cinnamon one) for about a year and I didn't know that it didn't have fluoride. I got three cavities (my first ones ever) that year. I don't think it's a coincidence. I think Tom's makes a version with fluoride; I'm not sure. The one I was using turned out to not have any. I shouldn't have assumed that it did. I don't drink tap water, so I wasn't getting any fluoride from that source.