Most foods are vitamin enriched and a normal diet contains adequate amounts of thiamine .
Beriberi can appear, however, in breast-fed infants when the mother has an inadequate intake of thiamine or among people whose diet includes certain types of fish that produce an enzyme which inactivates thiamine. Early symptoms of beriberi are nonspecific and include fatigue , irritability , restlessness , loss of appetite , and vague abdominal discomfort . As the disease progresses, patients develop burning sensations, tingling in the extremities, and changes in sensation such as numbness . Patients may develop psychosis . Death is generally a result of heart failure.