Nothing. Persimmons and crabs (or other foods high in protein) will be poisoned when eaten together. This is a completely wrong anecdotal legend, so ignore it. If you don't believe me, you can check the CCTV health programs and make it clear that it's false, so don't worry.

Explanation:

It is said that the tannic acid of persimmon will combine with the protein of crab (or other food with high protein content), causing poisoning.

Refutation 1: Persimmon has extremely low tannin content, which is not unique to him. If you eat it, you will be poisoned like other fruits.

Refutation 2: Tannic acid can promote digestion, and it will only be more easily absorbed by protein. . .

So, it's totally bullshit. Previous experience misled people, because persimmons and crabs are special products at the same time every year and were wrongly associated by the ancients.