Apples can't be eaten with seafood.

Apples contain tannic acid. Eating with seafood not only reduces the nutritional value of seafood protein, but also tends to cause abdominal pain, nausea and vomiting. Similarly, other fruits with much tannic acid, such as strawberries, bayberries, persimmons, pomegranates, lemons, grapes and sour pomelo, should not be eaten with seafood.

Other taboos for eating apples:

You can't eat apples at night

Many people are used to eating apples when they are hungry at night. Apples in the morning are golden, while those in the evening are rubbish. It's not good for your health.

Extended information:

Efficacy of apples:

1. Apples have the efficacy of reducing cholesterol content

Eating apples can reduce cholesterol content in blood, increase bile secretion and bile acid function, thus preventing cholesterol from precipitating in bile to form gallstones. Some experiments have found that more than 5% of people who eat apples regularly have 1% lower cholesterol content than those who don't eat apples.

2. Apples have the effect of lowering blood pressure

Apples contain more potassium, which can combine with excess sodium salt in human body and excrete it. When the human body consumes too much sodium salt, eating some apples is beneficial to balance the electrolyte in the body. The elements such as phosphorus and iron contained in apples are easily absorbed by the intestinal wall, and have the functions of nourishing the brain, calming the mind and sleeping.

Reference: People's Daily Online-Eating apples like this is very harmful. Four taboos for eating apples.