Vitamin D2 lowers your vitamin D3 — the word to check on the label, and the 10 vitamin D supplements we rank, all D3

Vitamin D comes in two forms. D2 is made from fungi or yeast exposed to UV light. D3 is the form your skin makes in sunlight.

Does one lower the other?

In blood levels, yes. A University of Surrey review pooled 11 randomized trials: people who took vitamin D2 ended them with about 18 nmol/L less vitamin D3 than control groups who took no supplement.

So is D2 useless?

No. D2 still raises total vitamin D, because D2 counts too. Whether the drop in D3 matters for health has not been studied, and the authors say more research is needed.

How do you know which one you take?

Look for one word on the label: ergocalciferol means D2. We read the labels of the 10 vitamin D supplements we rank: all 10 are D3.

The full answer, the prescription capsule, and the ranking:

https://super-achiever.com/news/vitamin-d2-lowers-d3

The short version, as a video:

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We put the full breakdown — every study, every number, with the PMIDs — on our own site.

👉 Read the full analysis

Originally published at super-achiever.com. We check viral supplement claims against the primary research and publish the results — including the ones that go against us.