Vitamin B6, molecular model. The chemical formula for vitamin B6, also called pyridoxine, is C8.H11.N.O3. Atoms are represented as balls and are colour-coded: carbon (blue), hydrogen (gold), nitrogen (dark blue) and oxygen (red). Vitamin B6 is found in a wide variety of foods, including poultry, fish, liver, vegetables, yeast and bananas. It is essential for the synthesis of amino acids, the building blocks of proteins. Deficiency of vitamin B6 is rare but may be caused by the use of hormonal contraceptives. Symptoms of deficiency include depression, insomnia, water retention and the inability to process glucose.