While it's true that too much fluoride can be harmful, it's totally safe in the small amounts found in toothpaste and water. In fact, it's naturally occurring in water to begin with. There are a lot of debates out there and some naturalists don't believe fluoride is good for you, but there's no evidence that the fluoride in water or toothpaste is harmful in any way. When it comes to toothpaste, the fluoride helps re-mineralize your tooth enamel, which is extremely important for the health of your teeth.