May 15, 2026, 7:11 pm | Read time: 4 minutes
Billy Bob Thornton dips grapes in Dijon mustard—not out of eccentricity, but necessity. In the podcast “Howie Mandel Does Stuff,” the actor discussed extreme dietary restrictions and one of the world’s rarest blood types. FITBOOK editor Michel Winges explains what’s behind it.
Ketchup Bagels and Mustard Grapes
In early May, Billy Bob Thornton appeared on the podcast “Howie Mandel Does Stuff,” hosted by U.S. entertainer Howie Mandel and his daughter Jackie.1 Right at the start, listeners might have been puzzled when Mandel began talking about an unusual food combination from the Thornton household. Mandel’s son and Thornton’s son are friends, and one day, when Mandel’s son was visiting, Thornton served him the affectionately named “Hillbilly Bagel”—a bagel with cream cheese and ketchup. Thornton, chuckling, admitted that he invents these combinations simply because he “can’t cook at all.” But the “Hillbilly Bagel” was just the beginning: Thornton quickly followed up with another culinary peculiarity that reportedly occurred recently at a press event. When a backstage buffet recently offered nothing suitable for him, Thornton experimented out of necessity: He dipped grapes in spicy Dijon mustard—and was thrilled. “It was one of the best things I’ve ever eaten. Now it’s become a regular habit for me,” said the actor.
Is the World’s Rarest Blood Type the Cause?
What sounds bizarre, and perhaps is, is simply because Thornton has no other choice. In the podcast, he explained: “Normally, they [backstage] have something I can eat because my diet is very restricted. I’m allergic to wheat and dairy. I have the blood type AB negative, which is the rarest type in the world—less than one percent of the world’s population has it. It means you have fewer digestive enzymes; that’s one of the things that come with it. I just grew up with a lot of allergies.”
What Thornton describes here needs to be put into context. His blood type AB negative is indeed rare, with less than one percent of the world’s population having this type, which is why it’s also known as the “phantom” among blood types.2 However, his allergies to wheat and dairy are likely completely independent of this. Both are widespread intolerances that—as far as research is aware—have nothing to do with blood type.
“My energy improved dramatically!”
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AB Negative Does Not Come with an Enzyme Deficiency
What Thornton describes here is reminiscent of the so-called blood type diet. A theory popularized by American naturopath Peter D’Adamo in 1996 with his bestseller “Eat Right 4 Your Type.” D’Adamo claimed that blood type determines which foods the body tolerates and how efficiently it digests them.3 Scientifically, this theory is now considered unproven. A systematic review in the American Journal of Clinical Nutrition concluded in 2013 that there is no reliable evidence for a connection between blood type and diet.4 The German Nutrition Society (DGE) also stated that their literature search found not a single conclusive study proving such a connection.5 Blood type determines certain characteristics on red blood cells but, according to current research, does not affect the production of digestive enzymes.
Also interesting: Cookbook author Stefano Zarrella: “Eggs are always a good idea!”
How Does AB Negative Restrict Thornton?
Blood type AB negative is primarily relevant in emergencies. As a recipient, Thornton can only receive Rh-negative blood during a transfusion. This makes medical care a logistical challenge, as Rh-negative blood is generally rarer. Some medical centers therefore store frozen AB-negative blood specifically for such cases. However, Thornton’s blood type has no proven impact on his diet, digestion, or allergies. What actually restricts Thornton are his allergies to wheat and dairy.