Why do people eat chalk

I caught my little niece eating chalk and she happily mentioned that it was her third piece for the day. I was shocked and confused and thought maybe she was just hungry. Later, after mentioning it to her mum, I was told that she has been eating tissue and paper too. I did some research on what would make a person crave for these things. And this is what I had found out, people who eat chalk are probably lacking nutrients and need to have a better diet. It could also be due to iron deficiency. This may also be caused from a mental health problem. However, if your child is eating chalk or if you are, I suggest you increase iron in your diet because that is most likely to be the case.  Often, women who are pregnant crave chalk and that it because they do not have enough iron in their body. I find it dangerous for a child to be eating chalk because they could possibly choke. Keep an eye on your kids and make sure that they have all their required vitamins to prevent these type of issues.