Bananas are an excellent source of vitamin B6, and contain moderate amounts of vitamin C, manganese and potassium. Along with other fruits and vegetables, bananas may be associated with a reduced risk of colorectal cancerand in women . Banana ingestion may affect dopamine production in people deficient in the amino acid tyrosine, a dopamine precursor present in bananas. Individuals with a latex allergy may experience a reaction to bananas.