Allah Most High says:
“O people! Eat of what is in the earth, Halal and Pure, and do not follow the footsteps of Satan. Indeed, for you he is an open enemy.” (Surah al-Baqarah, 168)
Sayyiduna Abu Hurayra (Allah be pleased with him) narrates that the Messenger of Allah (Allah bless him & give him peace) said:
“Allah the Almighty is pure and accepts only that which is pure. Allah has commanded the faithful to do that which he commanded the Messengers, and the Almighty has said: “O Messengers! Eat of the pure things and do right”. And Allah the Almighty has said: “O you who believe! Eat of the pure things We have provided you.” Then he (Allah bless him & give him peace) mentioned (the case of) a man who, having journeyed far, is dishevelled and dusty and who spreads out his hands to the heavens (saying): “O Lord! O Lord!” —while his food is unlawful, his drink unlawful, his clothing unlawful, and he is nourished unlawfully, so how can he be answered!”
Thus, the food we eat has a direct effect on us. It is the primary thing that needs to be considered by a Muslim. Supplications (dua) are not accepted due to consuming unlawful food. Hence, a Muslim should abstain from that which is doubtful also.