I Just Learned What Vitamin D Supplements Are Really Made From, And I'll Never Look At Them The Same Way

The NHS has advised Brits to take vitamin D supplements every day of autumn and winter until around March, as the lack of sun means we’re not making enough of it on our own. 

The vitamin is crucial to bone, gum, and muscle health, and too little vitamin D can cause rickets in children and in adults, a deficiency which can lead to bone pain caused by osteomalacia.

When our skin is given a chance, it usually produces enough of the stuff to keep us healthy via sunlight. 

But I’ve always wondered how vitamin D, which is also present in foods like oily fish, egg yolks, red meat, and liver, ends up in a capsule ― it’s pretty hard to literally bottle sunshine. 

What’s it made of?

Vitamin D supplements can be made from a variety of sources and comes in two forms. 

“In foods and dietary supplements, vitamin D has two main forms, D2 (ergocalciferol) and D3 (cholecalciferol),” US government research agency the National Institutes of Health writes.

Ergocalciferol comes from irradiated fungi (per peer-reviewed journal database site Science Direct), which a 2023 paper explains are “fresh or dried cultivated mushrooms with ultraviolet rays or sunlight.” 

It gets a little more interesting with cholecalciferol, however. 

The National Institute of Health says that “vitamin D3 is typically produced with irradiation of 7-dehydrocholesterol from lanolin obtained from the wool of sheep.”

In a way, both methods actually do “bottle sunshine” ― more specifically, they capture the action of sunlight on animal and plant cells in a way that’s available to our bodies.

Why are there two types of vitamin D?

Vitamin D3 (cholecalciferol) is the kind our skin makes when it interacts with sunlight, health information site Healthline explains.

Vitamin D₂ (ergocalciferol) only happens when plants like mushrooms react to the sunlight.

Though they “come from different sources but work in very similar ways,” Lloyd’s Pharmacy shared on their site. 

The main difference is that one is plant-based and the other is an animal product. 

Both are effective at treating vitamin D deficiencies when taken in the correct dose (adults should never go over 100 micrograms [mcg] a day, while kids under 10 shouldn’t have more than 50mcg; 10mcg is enough for most people).

So as we go into the colder months, remember to embrace whichever kind you prefer in order to keep your gums, skin, bones, and muscles healthy.