As a korean myself, I can say that kimchi is not really considered “spicy” to Koreans. It just happens to have chili peppers. When Koreans talk about spicy food, it’s the spiciness level of something like bulldak (spicy chicken) that has a lot more spicy ingredients. In relation to effects on health from eating a lot of spicy food, I don’t think you will find much in studying Koreans. Korean food is notoriously famous for being salty (especially soups that most Koreans eat daily) and a lot of Koreans suffer cardiovascular diseases from high blood pressure because of their diet.

On a side note, it’s really kimchi’s acidity that helps with cleaning palate much like Germans’ sauerkraut or Japanese’ pickled ginger (called “gari”) that you eat with sushi.