Vitamin D3
Cholecalciferol · Foundation
Fat-soluble vitamin most people are low in through winter. Corrects a deficiency; it is not a performance drug.
What the evidence says
Very large human trial base for correcting deficiency and bone health. Benefits in people who are NOT deficient are far less consistent.
What studies used
1,000–4,000 IU daily in most trials. With a meal containing fat.
Reported from published studies and product labelling — a record of what was used in research, not a recommendation. What is right for you is a conversation with a clinician.
Watch out for
- Fat-soluble — it accumulates
- Worth testing blood levels rather than guessing
Evidence base
established literature
Large human evidence base: several phase 3 or 4 trial reports, plus multiple meta-analyses or systematic reviews.
This letter measures how much human research exists, not whether it works for you — the tier above (Strong) is the read on quality.
Research (12)
- [Cholecalciferol (vitamin D3) must not be considered as an endocrine disruptor]Geriatr Psychol Neuropsychiatr Vieil · 2022
- Cholecalciferol (vitamin D3) is an agonist of the Alzheimer's disease-associated immune receptor TREM2Neurotherapeutics · 2026
- Alendronate/colecalciferolTreat Endocrinol · 2005
- [Vitamin D2 or vitamin D3?]Rev Med Interne · 2008
- Degradation studies of cholecalciferol (vitamin D3) using HPLC-DAD, UHPLC-MS/MS and chemical derivatizationFood Chem · 2017
- Vitamin D3 analoguesDermatol Clin · 1995
- [Vitamin D3]Pol Merkur Lekarski · 1999
- Vitamin D3 analoguesClin Dermatol · 1997
- The role of vitamin D3 in inflammatory bowel diseasesAdv Clin Exp Med · 2014
- [Vitamin D3-Intoxikation]Med Monatsschr · 1954
- [Vitamin D3]Lattante · 1950
- Tremendous Fidelity of Vitamin D3 in Age-related Neurological DisordersMol Neurobiol · 2024
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