Official educational / regulatory source · Official educational / regulatory source
Vitamin D supports calcium absorption and mineralization. Excess may cause hypercalcemia; thiazides, steroids and orlistat are relevant interactions.
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Strong human evidenceFat-soluble vitamin / hormone precursor
Vitamin D
Vitamin D helps regulate calcium absorption and bone mineralization. Correcting deficiency is not the same as preventing cancer or heart disease in otherwise healthy adults.
Also indexed as: Cholecalciferol · Vitamin D3 · Ergocalciferol · Vitamin D2
A clear starting point
Vitamin D is converted by the body into a signal that helps manage calcium. Too little can weaken normal bone mineralization; taking more is not automatically better.
Systems mapping shows biological relevance, not a treatment recommendation or a patient CPI score.
No validated chemical structure is displayed in this edition.
How it works
Vitamin D activation / VDR / calcium homeostasis
Vitamin D is converted by the body into a signal that helps manage calcium. Too little can weaken normal bone mineralization; taking more is not automatically better.
- Targets & processes
- Vitamin D receptor (VDR)
- Systems & tissues
- Intestine, bone, kidneys and parathyroid-linked calcium regulation.
What does the evidence show?
Established nutrient role in avoiding deficiency-related rickets and osteomalacia. VITAL found no significant reduction in its primary cancer or major cardiovascular endpoints.
What this does not establish
Prevention results in generally healthy adults do not answer every question about diagnosed deficiency or specific high-risk populations.
The New England journal of medicine · 2019 · Journal Article; Multicenter Study; Randomized Controlled Trial; Research Support, N.I.H., Extramural · PMID 30415629
Verified sample: 25,871 · US men aged 50+ and women aged 55+
No significant reduction in primary invasive-cancer or major-cardiovascular-event endpoints.
Limitations: Not a trial of treating diagnosed vitamin D deficiency.
Citation metadata from PubMed, a service of the U.S. National Library of Medicine, NIH. A citation match is not a guarantee of study quality. Abstracts are not full-text reviews.
Safety is a separate question
Excess intake can cause hypercalcemia and kidney injury. Symptoms may include nausea, weakness and confusion.
Contraindications & cautions
Hypercalcemia and disorders affecting vitamin D metabolism require clinician assessment.
Medication & supplement interactions
Thiazide diuretics may increase hypercalcemia risk; orlistat and glucocorticoids can alter vitamin D availability or metabolism.
Regulatory status · United States
United States: sold as a dietary supplement, not an FDA-approved drug for disease treatment. Ingredient research does not validate every marketed product.
This is not an exhaustive safety list. Regulatory status varies by jurisdiction and product; investigational use is not approval.
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Education only. Confidence labels are not formal systematic evidence grades. No patient record is used.