Vitamin D3
Technically a hormone, not a vitamin. Vitamin D3 (cholecalciferol) receptors are found throughout the brain, particularly in the hippocampus and prefrontal cortex. Deficiency — affecting an estimated 40-75% of adults worldwide — is associated with cognitive impairment, depression, and increased Alzheimer's risk. Supplementation is one of the most impactful interventions for people with low levels.
Dosage
Standard: 2000-5000 IU daily. Optimal blood level: 40-60 ng/mL (100-150 nmol/L). Most adults need 4000-5000 IU to reach optimal levels. Take with fat for absorption. Get blood levels tested before supplementing — both deficiency and excess are harmful.
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Half-Life
15-25 days
Administration
Oral (softgels, drops, tablets). D3 (cholecalciferol) preferred over D2 (ergocalciferol). Take with a fat-containing meal.
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Mechanism of Action
Vitamin D (1,25-dihydroxyvitamin D3) crosses the blood-brain barrier and binds to vitamin D receptors (VDR), a nuclear receptor expressed on neurons, astrocytes, microglia, and oligodendrocytes. VDR heterodimerizes with RXR and binds vitamin D response elements (VDREs) to regulate transcription. It upregulates neurotrophic factors: GDNF (glial cell line-derived), NGF, NT-3 via CREB and other transcription factors. Vitamin D promotes serotonin synthesis by upregulating tryptophan hydroxylase 2 (TPH2) and dopamine synthesis via tyrosine hydroxylase. It reduces neuroinflammation by suppressing microglial IL-1beta, TNF-alpha, and iNOS, and supports calcium homeostasis via regulation of L-type voltage-gated calcium channels and calbindin-D28k. Vitamin D regulates over 200 genes including those for neuroprotection, synaptic plasticity, and myelination.
Regulatory Status
Dietary supplement worldwide. RDA: 600-800 IU (many experts consider this inadequate). No prescription required except for high-dose formulations.
Risks & Safety
Common
Generally very safe at standard doses.
Serious
Toxicity at very high doses (>10,000 IU daily for months) — causes hypercalcemia (nausea, kidney stones, cardiac arrhythmia).
Rare
Headache, metallic taste, nausea.
Compare Vitamin D3 With
Research Papers
10Published: October 26, 2022
AI Summary
Next, we discuss the results of in vitro and in vivo experimental studies on the neuroprotective potential of 1alpha,25-dihydroxyvitamin D3 (calcitriol) in brain ischemia models. Despite the mixed results of the clinical trials, it appears that vitamin D3 still holds promise in preventing or ameliorating neurological and psychiatric consequences...
Published: July 15, 2020
AI Summary
A growing body of evidence highlights its crucial role in the regulation of reproductive processes in females. Furthermore, vitamin D3 deficiency has also been associated with polycystic ovary syndrome, premature ovarian failure and ovarian cancer.
Published: July 16, 2024
AI Summary
Additionally, the detection of vitamin D3 receptors (VDR) in follicles suggests that vitamin D3 may exert its effects by binding specifically to these receptors during follicular development. Further research indicates that vitamin D3 promotes follicular growth by enhancing the development of granulosa cells (GCs) and oocytes.
Published: January 21, 2023
AI Summary
The immune system (innate and adaptive) is influenced by vitamin D3, which affects gene expression and inflammatory pathways. An umbrella review was conducted to evaluate the power and accuracy of data connecting vitamin D3 to the outcomes of COVID-19 infection and to appraise the proof provided by
Published: March 30, 2023
AI Summary
Recent studies have paid special attention to other biological effects of calcitriol (the bioactive form of vitamin D3) with particular emphasis on its influence on immune function. Thus, any alterations, especially deficiencies, in the physiological level of calcitriol have serious health consequences.
Published: January 19, 2024
AI Summary
Two previous meta-analyses showed smaller differences between vitamin D3 and vitamin D2 in raising serum 25-hydroxyvitamin D [25(OH)D] and a consistently high heterogeneity when only including daily dosing studies.
Published: January 16, 2023
AI Summary
Hip fractures have a huge impact in reducing the quality of life and increasing mortality. This review aims to assess the impact of daily oral supplementation of vitamin D3 plus calcium on the incidence of hip fracture in people over 65 years.
Published: April 10, 2023
AI Summary
There is still controversy over the effect of vitamin D3 supplementation on bone health.
Published: October 21, 2024
AI Summary
Vitamin D3, which originates from cholesterol, exerts its influence on immune cells and potentially cancer cells via the metabolite 1,25-dihydroxycholecalciferol (1,25(OH)2D3), impacting their proliferation, differentiation, and apoptosis. An umbrella review was conducted to evaluate the potential p
Published: February 8, 2024
AI Summary
Furthermore, prevention of ageing processes induced by the chronic inflammation requires the maintenance of healthy gut microbiota, which is related to daily dietary habits. In this regard, supplementation of vitamin D3 and phytochemicals plays an important role.
Frequently Asked Questions
What is Vitamin D3 used for?
Technically a hormone, not a vitamin. Vitamin D3 (cholecalciferol) receptors are found throughout the brain, particularly in the hippocampus and prefrontal cortex. Deficiency — affecting an estimated 40-75% of adults worldwide — is associated with cognitive impairment, depression, and increased Alzheimer's risk. Supplementation is one of the most impactful interventions for people with low levels.
What are the side effects of Vitamin D3?
Common: Generally very safe at standard doses. Serious: Toxicity at very high doses (>10,000 IU daily for months) — causes hypercalcemia (nausea, kidney stones, cardiac arrhythmia). Rare: Headache, metallic taste, nausea.
How is Vitamin D3 administered?
Vitamin D3 is administered via oral (softgels, drops, tablets). d3 (cholecalciferol) preferred over d2 (ergocalciferol). take with a fat-containing meal..
What is the half-life of Vitamin D3?
The half-life of Vitamin D3 is 15-25 days.
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