Let's start with shark fin. Foreigners always wonder why people in China like to eat shark fin. They think that shark's fin is a kind of thing with few nutrients and no special taste, and they are puzzled by this preference of China people.
In fact, it is not a long history for China people to regard shark fin as a valuable delicacy, and it should start from the Ming Dynasty. First seen in Compendium of Materia Medica, Li Shizhen said that sharks "have wings under their bellies and are delicious, which are treasured by southerners".
The shark fin itself has no special taste. The delicacy of shark fin soup we eat mainly comes from its ingredients, which are cooked with real delicacies such as ham and old hen.
The reason why shark fin is respected is also related to the so-called health preserving culture of China people. Chinese medicine believes that shark fin can "invigorate qi, tonify deficiency and stimulate appetite", while modern gourmets say that shark fin is rich in nutrition and collagen, which can prevent bone aging and nourish skin.
From a nutritional point of view, shark fin has no special nutritional value. Its main component is collagen, which is a kind of protein. Collagen eaten by people is digested into amino acids in the gastrointestinal tract and then absorbed by the human body. No matter what protein you eat, it is digested into the amino acids that make up protein. Therefore, the nutritional value of shark's fin is not particularly obvious, and it is better to completely contain fish from protein.
Another shark fin will kill a shark. From the perspective of animal protectionism, it is really cruel. These are the reasons why foreigners don't eat shark fin.
Let's talk about bird's nest again. Besides China people, people in Southeast Asian countries also like to eat it. Foreigners who don't eat bird's nest here are probably from western countries.
There should be a reason why they don't like bird's nest. First, they think that bird's nest is made of swallow saliva, which is very unclean. Just thinking about it makes them sick, just like the reason why they won't eat chicken feet.
Then there are eating habits. In western recipes, I don't know how to make bird's nest at all.
Then it is related to animal protection. They think that the bird's nest is made by swallows, and people cruelly take it down as food for their appetite.
Then there is scientific research. There is nothing special about the nutrition of bird's nest.
These are the general reasons why foreigners don't eat shark's fin and bird's nest.