When it comes to naturally occurring spicy foods, some animals are more fit than others to enjoy them. Humans and other mammals aren't so well equipped to handle those foods. Take the chili pepper, for example. While it's a food rich in anti-inflammatory and antioxidant properties and serves as an excellent source of vitamin C, it contains capsaicin — a chemical that makes peppers taste spicy and interacts with the nerve receptor known as TRPV1.
While some humans may classify the tingling and burning associated with capsaicin as pleasant, it is a fierce deterrent for animals. The Environmental Protection Agency actually classifies capsaicin as a biochemical pesticide and animal repellant. However, not every animal shies away from spicy foods. Some can handle the heat without breaking a sweat.
Natural Aversions to Spice
Mammals, including humans and rodents, have pain receptors that can be activated by injury, acid, heat, and the phytochemical capsaicin. Capsaicin can be lethal to rats and mice, and symptoms of acute oral toxicity can include a staggering gait, skin redness, and cyanosis — blue lips, nail beds, and skin due to low oxygen levels.
