What is the garlic myth supposed to base on?

I found this answer on yahoo answers;

Garlic is another ancient method of fending off evil spirits. Garlic has been used in cultures throughout the world as a healing medicine and natural vitamin. It was thought to have a purification principle much like the metal Silver. People would hang it outside their doorways to keep evil spirits from entering their homes. The ancient societies got a little carried away with Garlic condemning anyone who had an aversion to garlic as a vampire. Garlic was also passed out during church ceremonies so that church official could be sure that no evil spirits were attending. THE MYTH Vampire myths go back thousands of years and occur in almost every culture around the world. Their variety is almost endless; from red eyed monsters with green of roze hair in China to the Greek Lamia which has the upper body of a woman and the lower body of a winged serpent; from vampire foxes in Japan to a head with trailing entrails known as the Penanggalang in Malaysia.

hope this helps =D