how does the cannibals' food affect Marlow

This does not affect Marlow in any physical way. As they chug down the river, food becomes ore scarce. The foreign pilgrims seem to eat okay but the crew, mostly cannibals, are starving. Marlow notes that the crew outnumber the pilgrims and could easily chow down should they want to. The Cannibals subsist on some pretty nasty stuff. This includes rotten hippo meat. Marlow, as the Pilgrims, find it nasty and putrid. The Pilgrims hoist it overboard which Marlow thinks is pretty stupid considering the only other meat around is pudgy white man-flesh.