United Kingdom, May 10 -- Billy Bob Thornton's diet is "very restricted" due to rare health issues.

The Landman actor has a number of food allergies and believes his rare blood group has led to additional stomach issues, despite no studies definitively showing a clear link between blood type and help.

Speaking on the Howie Mandel Does Stuff podcast, Billy Bob explained: "Well, I'm allergic to wheat, dairy. I have type AB-negative blood, which is the rarest type in the world. It's, like, less than 1% of the population of the world has it.

"It means you have less digestive enzymes. That's one of the things that goes along with it."

The 70-year-old actor "grew up with a lot of allergies but "ate everything" and just assumed most people d...