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evidence · mechanism · dose
Supplements/Vitamin

Vitamin D3 (Maintenance)

Daily maintenance dose for non-deficient adults.

Bone HealthImmune FunctionGeneral Wellness

Overview

Daily maintenance dose for non-deficient adults.

Natural sources
    Common forms

      Forms & variants of Vitamin D3

      Different chemical forms of Vitamin D3 behave differently. Browse each form's mechanism, bioavailability, and best-use context.

      Parent
      Vitamin D3

      Steroid hormone precursor regulating ~5% of the human genome — bone, immune, and hormonal health.

      D3 (Cholecalciferol)
      Vitamin D3 (Cholecalciferol)

      Preferred form for raising 25(OH)D — the active form your skin makes from sun.

      Repletion 5000–10000 IU
      Vitamin D3 (Repletion)

      Repletion dose for deficiency under medical supervision.

      Mechanism of action

      Hormone precursor regulating ~3% of the genome via VDR.

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Maintains 25(OH)D 30–50 ng/mL

        Strong evidence

        Potential side effects

        Common
          Rare
          • · Hypercalcemia at very high dose
          Serious

            Drug interactions

            No notable interactions reported.

            Safety & non-supplemental interactions

            Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

            Avoid with these conditions
            • ·Autoimmune disease (theoretical immune activation)
            Avoid / monitor with these medications
            • ·Immunosuppressants

            Supplement interactions

            Pairs well with

            None listed.

            Avoid combining with

            No specific avoidances listed.

            Dosing & bioavailability

            Typical dose
            1000–2000 IU/day
            With food?
            With fatty meal

            Where to buy

            Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

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            Thorne
            Practitioner-grade · NSF tested

            Scientific evidence (8)

            RCTAm J Clin Nutr · 2003

            Vitamin D maintenance dose-response

            Heaney RP, et al.

            Dose-response trial in 67 men.

            Key findings

            1000 IU/day raised serum 25(OH)D by ~10 ng/mL.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — Maintains 25D 30–50 ng/mL

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) Maintains 25D 30–50 ng/mL" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "Maintains 25D 30–50 ng/mL". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — randomized controlled trial

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — meta-analysis

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — pharmacokinetics

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — safety adverse events

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewPubMed (NLM) · 1970

            PubMed: Vitamin D3 (Maintenance) — dose response

            Live PubMed search

            Live results for "Vitamin D3 (Maintenance) dose response" across the PubMed/MEDLINE peer-reviewed index.

            Key findings

            Opens current human and preclinical literature matching Vitamin D3 (Maintenance) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

            Open study
            Systematic reviewGoogle Scholar · 1970

            Google Scholar: Vitamin D3 (Maintenance) — clinical evidence

            Live Scholar search

            Cross-database citation index for Vitamin D3 (Maintenance) as it relates to "clinical evidence".

            Key findings

            Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

            Open study
            Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.