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Vitamin

Vitamin D3

Vitamin D3, or cholecalciferol, is one form of the fat-soluble vitamin D. Skin makes it in response to UV light, and it also comes from foods and supplements.

Also listed as Cholecalciferol, Vitamin D, D3, Vitamin D-3

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How much is too much?

The US adult upper intake level is 100 µg (4,000 IU) daily from all sources. Excess supplementation can cause high blood calcium, with nausea, weakness, thirst and kidney problems; severe toxicity can cause renal failure and abnormal heart rhythms. The upper limit is not a recommended routine dose. 1

Which medicines matter?

Thiazide diuretics reduce calcium excretion, so combining them with vitamin D can increase the risk of high blood calcium, especially with kidney impairment or hyperparathyroidism. Orlistat can reduce vitamin D absorption, while corticosteroids can impair its metabolism. NIH recommends discussing intake and status with the treating clinician when medicines affect these pathways. 1

Does everyone need a vitamin D test?

The Endocrine Society advises against routine screening in healthy adults without an established testing indication. It also prefers daily lower doses to intermittent higher doses for adults aged 50 or older who need supplementation or treatment. 2

For information, not individual medical advice. Ingredient studies do not establish the effectiveness of these products.

Sources

  1. Vitamin D: Fact Sheet for Health Professionals NIH Office of Dietary Supplements