Actor Billy Crystal has switched up his diet after discovering he is allergic to wheat products.

The Princess Bride star had been struggling with intestinal problems for several weeks earlier this year (12), and medics determined Crystal's body was unable to digest all things containing wheat, such as pasta and bread.

He has since hired a nutritionist in Los Angeles to provide him with special meals.

He tells U.S. Tv host David Letterman, "I found out a couple months ago that I'm allergic to wheat... It's not like it's in nothing. It's in everything... It's no pasta, white flour, everything, it's awful.

"But I feel a lot better... I found this company in Santa Monica, because I'm in the middle of this press tour (for new movie Parental Guidance) (and) I had to be in good shape, that they made all those gluten-free foods.

"So they deliver the food in, like, a cooler with a zipper and a plastic lock every morning and they leave it at the inside of the front gate (at my house), and I have the food for every day, and it's great."

But the veteran entertainer admits the raccoons sometimes get to his food first.

He adds, "They figured out how to get into the lock and unzip the food and they eat all my diet food. And, you know something, they look fabulous. It went a long way for them."