We know that in the Buffyverse, garlic is effective against vampires:
CLOSE: ON WINDOW
Where a bunch of fresh garlic is now nailed.
To find that there is garlic nailed up at all the windows. Buffy sits up in bed, looking small and scared, holding a cross.
Source: the script for Wrecked, season 6 episode 10.
This leads me to the question, does Buffy eat garlic? The smell must repulse vampires, adding an extra layer of protection.