One who is a Brahmana, when he becomes wicked in conduct and observes no distinction about food, falls away from the status of Brahmanahood and becomes a Shudra.
ब्राह्मणो वाप्यसवृत्तः सर्वसंकरभोजनः। ब्राह्मण्यं स समुत्सृज्य शूद्रो भवति तादृशः॥