A word for eating and drinking, and a word for taking a substance

Solution 1:

The most common word for it is consume - to eat or drink something

Try ingest - it means to take (food, drink, or another substance) into the body by swallowing, eating or absorbing it.

Solution 2:

I think vickyace's consume is good choice, but another option that works for food/drink/drugs is to partake

1 (partake of) Eat or drink (something): he partook of a well-earned drink

2 (partake in) Join in (an activity): visitors can partake in golfing or clay pigeon shooting

3 (partake of) Be characterized by (a quality): the birth of twins became an event which partook of the mythic

http://www.oxforddictionaries.com/definition/english/partake