Overview
- The latest coverage explains that skin makes vitamin D only when the sun sits high in the sky, with a simple check that a shadow shorter than your height or a solar elevation near 42 degrees signals production is possible.
- Health bodies converge on modest daily doses for maintenance, with the DGE at 800 IU and the Endocrine Society at 600–800 IU, and they set an upper safe limit of 4,000 IU (100 micrograms) for adults.
- Experts prefer steady daily dosing over infrequent large doses, and routine blood testing is not recommended for healthy people unless there is a clear medical reason.
- For a confirmed deficiency, clinicians use short high-dose therapy for about a month before stepping down, with a rough rule that 10,000 IU raises 25(OH)D by about 1 ng/ml and higher body weight often requires more.
- Officials caution against self-medicating with high-strength products, note that vitamin D3 is the more effective form than D2, and advise taking tablets with a fatty meal to improve absorption.