Extract from a Tablet of ‘Abdu’l‑Bahá

Thou didst ask about not combining incompatible foods at the table.¹ By incompatible foods is meant those dishes that do not agree with one another. However, He hath not stipulated whether these are to be determined according to the ancient school of medicine or the modern one. What is meant is that if two incompatible foods are served together at the table, it is not permissible to partake of both. And this dependeth on one’s constitution and on whether the digestive system is weak or strong. For instance, to consume two heavy foods or two dishes whose ingredients are both either cold or hot by nature may not agree with a delicate constitution. Or perhaps one’s natural disposition may not tolerate two different forms of a certain food or two foods each of which would impede the digesting of the other. Hence it is not permissible to combine these foods. This is a matter that must be determined by physicians. Whatever foods physicians forbid a person to combine would be regarded as incompatible.

—‘Abdu’l‑Bahá