Cholecalciferol, a.k.a. vitamin D3, is the form of vitamin D that is created when sufficiently intense sunlight hits our skin. It’s also found in modest amounts in fatty fish, such as salmon. In nutritional supplements, D3 is typically derived from lanolin, a byproduct of wool making. It can also be sourced from some species of lichen, a rare exception to the D3-from-animals-only rule.
Ergocalciferol, or D2, is typically a synthetically produced form of vitamin D, although it can be synthesized by irradiating or sun-drying certain species of mushrooms. It used to be the predominant form of vitamin D found in supplements.
However, since vitamin D3 is more efficient at raising blood levels of vitamin D, carries less risk of toxicity, and is more stable, it has largely replaced D2 on store shelves. Double check the fine print on product labels to be sure which type of vitamin D you’re buying.
To learn more, read “Changing Conditions” in the March 2021 issue of alive Magazine.