How to identify what is beneficial and what is harmful?

How to identify what is beneficial and what is harmful?

The digestive system is considered the only system that God has placed under the direct control of human beings; it has inputs and outputs, and a person does not always need a doctor to tell them what is beneficial or harmful.

For example, if someone eats arugula and experiences bloating, gas, or cramps, it may be better not to consume it. Likewise, if eating bread leads to digestive disturbances, this indicates that it may not be suitable for that individual.