What is the definition or description of: vitamin b deficiency?

Beriberi: Is the classic presentation of bgroup deficiency, chiefly vitamin b1 (thiamin). Beriberi has been a scourge for centuries from eating white rice. In its early stages it causes dysautonomia (abnormal functions of the autonomic [automatic] nervous system) and dysautonomia is widespread and common in the U.S. Because of the widespread consumption of sugar.

Various: Severe deficiency symptoms are rare and include dermal - seborrhea-like rash, atrophy of the tongue, rash in the corner of the mouth (usually vitamin b2 deficiency) and neurological - mental lethargy, sleepiness and disturbance in nerve sensation. Rarely, vitamin b6 deficiency can cause seizures in infancy. Milder deficiency can lead to problems with mood, sensory overload & stress intolerance.