system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why anemic people(especially pregnant women)crave ice?What is the correlation between anemia and ice?
gpt
Craving ice is a form of pica, which is a symptom in many illnesses and includes craving all sorts of non-food items such as clay, dirt and paper. 

The exact cause is unknown, but there are theories that the cravings are the body trying to replace whatever it is you're deficient in (i.e. iron in anemia sufferers). There are also suggestions that anemia causes lowered dopamine levels, and pica is thought to be associated with low dopamine, so that is a possible link.