Meat and drink in this phrase has two meanings, which appear to be independent of each other. Either, to be a source of support or pleasure or, to be a simple and routine matter.

It isn't clear which of those two meanings is intended in the earliest known use of the phrase - John Frith's, A boke answering vnto M. Mores lettur, 1533:

"It is meate and drinke to this childe to playe."

Shakespeare used the phrase in As You Like It (1616) and the meaning there is clearly the former:

"It is meat and drinke to me to see a Clowne."