Scriptures have stated hundreds of foods that are unfit for consumption as per its gradation. Saints have univocally accepted that consuming intoxicating substances such alcoholic drinks will reap greater sin. Onion and garlic come in next in the list that are to be completely avoided. Many scriptures have specifically mentioned that these two must be avoided. There are many vegetables and fruits that are to avoided by Brahmins.
One can click the link below to verify the proof about foods that are to be avoided, the sins one gets for consuming it and the atonements for consumption.
https://youtu.be/XAGaZQgqj48 Sri Desikan Upadesam – Saappidave koodaadha vasthukkal | Vande Vedantha Desikam