Vitamin D3 is crucial for calcium absorption, bone health, and immune function, obtained from sunlight, diet, or supplements.
Vitamin D3 (cholecalciferol) is a fat-soluble vitamin crucial for calcium absorption, bone health, and immune function. Synthesized in the skin through UVB exposure or obtained from dietary sources/supplements, it undergoes two hydroxylations (liver and kidneys) to become the active form, calcitriol. Calcitriol acts as a hormone, regulating gene expression through the vitamin D receptor (VDR) and influencing bone metabolism, immune responses, neuromuscular function, and cell growth. While beneficial, excessive intake can lead to hypercalcemia and other adverse effects. Dosage should be appropriate and possibly guided by medical professionals, especially when considering higher doses.
Key Information
Inside Body Harmful Score
Common Dosage
400-4000 IU daily, with higher doses sometimes prescribed under medical supervision.
Source Type
natural
Production Process
Synthesized in the skin upon exposure to UVB radiation from sunlight or obtained from animal-derived sources like lanolin (sheep's wool) or fish liver oils. Can also be produced industrially through irradiation of 7-dehydrocholesterol.
Use Type
Inside BodyPotential Benefits
Enhances natural testosterone production for improved muscle mass, strength, energy, and libido. This benefit works by supporting Leydig cell function, reducing estrogen, and increasing free testosterone.
Enhances bone density, strength, and integrity by supporting bone formation, calcium absorption, and reducing age-related bone loss. Improves overall skeletal health and function, ultimately reducing the risk of fractures.
Immune support enhances the body's defense against pathogens by strengthening immune cells, promoting antibody production, and maintaining immune homeostasis. It aims to optimize immune function for a balanced and resilient response to threats.
Mood regulation is the body's ability to maintain emotional balance through a complex interplay of neurotransmitters, hormones, and brain regions. Effective mood regulation supports stress management and a stable sense of well-being.
Enhances and maintains the proper functioning of muscles, improving strength, power, endurance, and coordination. Optimal muscle function is crucial for mobility, balance, posture, and reduces risk of injury.
Supports healthy immune cell function
Possible Side Effects
High vitamin D can cause high calcium, leading to nausea and weakness.
Stomach upset, often related to dosage amount.
Gastrointestinal issues include nausea, diarrhea, abdominal discomfort, and vomiting, potentially stemming from altered gut motility, microbiota changes, or irritation. While often mild, persistent symptoms necessitate evaluation, and contributing factors like pre-existing conditions should be considered.
Vitamin D3 supplementation, especially at high doses, can cause nausea and vomiting due to hypercalcemia stimulating the brain's chemoreceptor trigger zone. Severity can range from mild discomfort to pronounced emesis, and prompt reporting to a healthcare provider is advised.
Excessive vitamin D3 intake can paradoxically lead to weakness and fatigue due to disrupted calcium homeostasis affecting nerve and muscle function. This can be accompanied by other symptoms of vitamin D3 toxicity.
Scientific Evidence
National Institutes of Health (NIH) Office of Dietary Supplements - Vitamin D Fact Sheet; scientific publications indexed in PubMed and Google Scholar focusing on vitamin D3 supplementation, deficiency, and effects on bone health, immune function, and other physiological processes.
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