1. The original comment was deleted. My comment would make more sense in context.
2. FUD is using false information to spread fear, uncertainty, and doubt. When someone claims nutritional supplements have some sort of miraculous medical benefit, that is FUD. It is FUD because it is almost certainly false information and it helps to create doubt and uncertainty of mainstream medical science.
3. If OP provides empirical evidence that using nutritional supplements regrows enamel, I will admit I was wrong. The wider medical community would also be very interested.
