They are not mutually exclusive.

According to the query on 39 Health Network: Dragon fruit and crab are not incompatible and can generally be eaten together, but do not overdose. Dragon fruit is a fruit rich in vitamins, carbohydrates, and sugars. Moderate consumption can promote digestion and enrich nutrition for the body. Crab is a food with high protein, low fat, low sugar and high mineral content. Eating it in moderation has a certain nourishing effect on the body. Although dragon fruit and crab are both cooling foods, if they are eaten in large amounts, they may cause some irritation to the gastrointestinal tract. Especially people with weak spleen and stomach and weak constitution are more likely to suffer from abdominal pain, diarrhea and other uncomfortable symptoms. Moreover, the protein in crab may combine with the tannic acid in dragon fruit. Eating a large amount together is not conducive to the digestion of the gastrointestinal tract, and may easily cause indigestion and other conditions.

When eating dragon fruit and crab, you should pay attention to the appropriate amount, or you can eat them separately for a period of time. And the diet should be diversified. Avoid eating only dragon fruit and crabs. You can eat it with other meats, vegetables, etc. to enrich the nutrients in the body.