Should the government add elements to, or alter our (air, food, whatever) without allowing citizens’ choice in the matter?

This question is intended to engender a discussion about the power of the government to add or alter elements to our water (air, food, whatever) without allowing citizens’ choice in the matter. To take an example from a previous question, water is necessary for life, but fluoride is not. But we have already had a long discussion about fluoride and its benefits versus harm, so this question isn’t about fluoride.