What is Vitamin D3?
Vitamin D3 is made in the skin under UV light or taken in with food and is converted in the body into its active hormone form. It mainly regulates calcium and bone metabolism; deficiency causes rickets or osteomalacia.
How well studied is Vitamin D3?
Treating a deficiency is well established. However, large trials such as VITAL found no protection against cancer, heart attack, stroke or fractures in people without marked deficiency. D3 raises blood levels more and for longer than D2.
What side effects and risks does Vitamin D3 have?
Overdose – almost always from high-dose supplements – raises calcium in blood and urine, causing nausea, kidney stones and kidney damage. Thiazide diuretics combined with vitamin D can raise calcium further; orlistat reduces absorption. High intakes should be monitored by a doctor with blood tests.
Is Vitamin D3 approved in Germany?
In short: yes. Approved as a medicine in Germany (partly over the counter, some higher-strength products prescription-only) and also available as a dietary supplement. Not on the WADA Prohibited List.
Sources
Note: We deliberately do not list any doses here. For approved medicines, your doctor sets the dose; for unapproved substances there is no reliable information.