My best friend eats chalk
She can't seem to stop it. She's 17 and she's still eating it. Her parents have tried various methods like giving calcium tablets and buying chocolates(she likes chocolates a lot). Her parents are also really strict so they if I tell them, they'll do something extreme(they believe she stopped a year ago). I tried some emotional methods like not talking to her for a while because she eats chalks(we're best friends). Nothing could stop her and I feel like I'm the only one who can help without being disgusted by it. First of all, I don't know why people eat chalk(I've heard of such stories before).
What can I do to make her
stop?

It could just be a weird habit she formed growing up, much like kids eating glue, or people who eat toilet paper, chew pencils.
try this Site

seeking medical advice and help is what should be done, easy enough to bring your friend to the hospital, but make sure she knows, that way you aren't misplacing her trust, there would be very few reasons to inform the parents, but i doubt they could literally 'punish' her, strict doesn't mean Disciplinary. they're just concerned.
my brother ate pencils like a beaver throughout elementary, he stopped shortly before grade 8, sometimes a person grows out of it

Thanks for that link!
Her parents don't trust her and she's very emotional, sometimes she tells me she wants to die.
She did get medical help but they just said that she was probably deficient. Her parents got her calcium tablets and it still didn't work.

https://en.wikipedia.org/wiki/Pica_(disorder)

"The scant research that has been done on the causes of pica suggests that the disorder is a specific appetite caused by mineral deficiency in many cases, such as iron deficiency, which sometimes is a result of celiac disease or hookworm infection. Often the substance eaten by someone with pica contains the mineral in which that individual is deficient. More recently, cases of pica have been tied to the obsessive–compulsive spectrum, and there is a move to consider OCD in the etiology of pica. However, pica is currently recognized as a mental disorder by the widely used Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Sensory, physiological, cultural and psychosocial perspectives have also been used by some to explain the causation of pica.[citation needed]It has been proposed that mental-health conditions, such as obsessive-compulsive disorder (OCD) and schizophrenia, can sometimes cause pica.

However, pica can also be a cultural practice not associated with a deficiency or disorder. Ingestion of kaolin (white clay) among African-American women in the US state of Georgia shows the practice there to be a DSM-IV "culture-bound syndrome" and "not selectively associated with other psychopathology". Similar kaolin ingestion is also widespread in parts of Africa. Such practices may stem from health benefits such as the ability of clay to absorb plant toxins and protect against toxic alkaloids and tannic acids."

Maybe find something for her to be interested in that's less dangerous? I'm no expert but it might help. You could try introducing her to a particular sport that she might come to like. Anything that'll distract her so she won't itch for some chalks. Good luck and I wish your best friend all the best!

My best bet is to try to help her slowly overcome it. It's probably not easy getting over a bad habit, but it's possible if you take it easy.

Thanks guys.. I'm trying to reduce it but I don't know if it'll help. Thank you.