Cobalamin (vitamin B12) was discovered in the first half of the 20th century. Vast amount of information on the role of the vitamins in human health and disease became available. Cobalamin science was, however, based on theoretical concepts that have been accepted without further proof of facts and hypotheses. Recently, the breath-taking pace of development in research technologies has changed our understanding for the role of nutrients and the complex interaction between diet, environment and diseases. Conditions like aging, diet and drugs increase the risk of developing cobalamin...