Ask most Japanese what "kombucha" is, and they say it is a mild, brownish kelp-based tea.

But across New York and the rest of the United States, a growing number of fans know kombucha as a lightly carbonated, sweet fermented tea said to possess nearly magical health benefits, including possibly warding off cancer.

Kombucha's slightly sour flavor and smell mainly divides people into two camps — those who swear by it and those who can't stand it.