Researchers say Rudolph is most at-risk from Christmas travel due to his bright red nose and have determined the best foods to leave out for Santa's lead reindeer on Christmas Eve.

Reindeer noses have a complex system of tiny blood vessels that prevent them from freezing, but also results in loss of body heat. Because Rudolph's nose is the reddest of them all, he poses a greater threat.

"That's bad. You want to retain as much heat as possible. If Rudolph has a very bright, glowing nose, he must have an unusually rich microvascular system, and he's probably losing a ton of heat through his nose," says Nathaniel Dominy, anthropology professor at Dartmouth College. "So Rudolph, more than other reindeer, is probably risking his life by losing so much heat."

Dominy suggests families skip leaving carrots out for the reindeer on Christmas Eve - instead, he says, opt for cookies.

"One way to heat your body is to burn fuel. You do that by burning fat and calories," says Dominy. "Children should be aware of Rudolph's condition and leave high-calorie foods for him."

When buying or baking cookies for the reindeer, keep in mind the ingredients you should avoid giving them:

  • Chocolate
  • Coffee
  • Citrus
  • Coconut and coconut oil
  • Raisins
  • Macadamia nuts
  • Nuts
  • Milk and dairy
  • Xylitol

If your cookies have those ingredients, no need to worry - we hear Santa loves chocolate and macadamia nuts!