Rickets in children is rare today but its senior-age equivalent, Osteomalacia - softening of the bones - is a growing health concern.

       To prevent rickets 100 years ago, children were often dosed with castor oil.

       It was known that castor oil contained Vitamin A but another vital substance was discovered which turned out to be Cholecalciferol, an important bone-building hormone.

Cholecalciferol was mis-named as a vitamin because it was discovered after vitamins A, B and C [2].

Cholecalciferol or “vitamin” D3, was added to the public milk supply in the 1930s to prevent rickets - it’s still there – but it only works if you drink milk.

Vitamins are eaten, in foods or supplements, but Cholecalciferol is a hormone, made by the body from cholesterol when sunlight strikes the skin.           

D3 obtained through sunlight has the effect of lowering cholesterol, a heart benefit not received with a D3 supplement.

When Cholecalciferol was discovered stored in the kidneys, after the invention of the electron microscope (1980), it was named 25[OH]D. Or “vitamin D3.”