25µg tablets of cholecalciferol or vitamin D3. It is also known as toxiferol. It is sold as a vitamin food supplement which can otherwise be synthesised in the skin by UV light, or sunshine, so has become known as the 'sunshine vitamin'. It can be extracted industrially from the lanolin in sheeps' wool or from lichen. It became known through research into childhhod rickets, which was found to be due largely to a deficiency in this compound and which is characterised by a softening and deformity of the long bones.