Is lactose intolerant (which means she can't digest any dairy product), which is ironic as her character on Buffy the Vampire Slayer (1996), Amy Madison, was turned into a rat for three seasons. When she was turned human and asked what she wanted to eat, she replied "Anything. Not cheese".
She had originally auditioned to play the part of Buffy, but didn't get the role. However, months later when the producers were looking to cast the part of Amy Madison, they remembered her and brought her in. Amy was supposed to be a one-time character, but she wound up recurring over the years.
She is convinced that Amy was only reverted back to human from rat form because of the intervention of the fans. A number of viewers had written to the producers saying that the natural lifespan of a rat is only 3 years, and that if Amy wasn't made human again soon, she would die. That spurred an amused Joss Whedon to find a way to bring Amy back again.