Vitamin B12 comes from microorganisms that live in the soil.  These are then ingested by animals.  Eating animal products is only one way of obtaining Vitamin B12.  It can also be manufactured by cultivating yeast – this is how vegans obtain it.  People argue that supplements are not natural.  However, many nutrients are already being obtained by supplementation. For example, iodine is added to salt and folic acid is added to bread.  Many non-vegans, especially those over the age of 50, are deficient in Vitamin B12 and are advised to supplement with it. Irish people are deficient in Vitamin D during the winter months due to the lack of sunshine and are advised to take Vitamin D supplements.