Yes, coconut milk can help reduce the sensation of spiciness in food.
While coconut milk doesn't contain casein, the protein found in dairy that is particularly effective at binding to capsaicin (the compound that makes chili peppers spicy), it does contain a significant amount of fat. This fat can help dissolve capsaicin, which is also fat-soluble, and thus reduce its impact on your taste receptors. This helps to calm the heat and cool down the overall spiciness of the dish.
Essentially, the fat in coconut milk acts as a solvent, lifting the spicy oils away from your tongue. This is a similar principle to why dairy products (which contain both fat and casein) are often recommended for combating spiciness. While not as potent as dairy in some cases, coconut milk is a great option, especially for those who are lactose intolerant or prefer plant-based solutions.
