"...Any cat older than that detected eating litter should be taken to a veterinarian, since this behavior often indicates anemia or other dietary deficiencies."

Yes, I found that my cat loves salty things (sodium-deficiency?) such as Doritos.


http://www.scientificamerican.com/article/would-you-like-side-dirt-eating-soil/


"Elephants, gorillas and bats eat sodium-rich clays when they do not get enough sodium in their diet. One elephant population is known to continually visit underground caves where the animals dig up and eat salt-enriched rock."




This may be, according to one theory, one of the causes of Ebola escaping into modern life:

https://en.wikipedia.org/wiki/Kitum_Cave

"...The walls are rich in salt, and animals such as elephants have gone deep into the cave for centuries in search of salt. The elephants use their tusks to break off pieces of the cave wall that they then chew and swallow, leaving the walls scratched and furrowed; their actions have likely enlarged the cave over time."

(and possibly exposed the Ebola virus in the cave to other things, such as Monkeys and bats.





A fairly decent book that I've read: (There may be others, your library may have this one.)

http://www.amazon.com/Lots-Wife-Salt-Human-Condition/dp/0805009205/ref=sr_1_1?s=books&ie=UTF8&qid=1449261260&sr=1-1&keywords=lot%27s+wife

Hardcover: 14 cents.