Vitamin B12
Vitamin B-12 is the largest and most structurally complicated vitamin. It is found in meat products and can only be produced industrially by bacterial fermentation synthesis. Vitamin B-12 is essential for normal brain and nervous system function. It is also involved in the production of red blood cells and helps to create and regulate DNA. The metabolism of every cell in the body depends on vitamin B-12 because it plays a role in fatty acid synthesis and energy production. Symptoms of vitamin B-12 deficiency include constipation, loss of appetite and weight loss.