Calciferol D3 (Vitamin D3) - Function and Deficiency
Calciferol D3 (cholecalciferol) is the natural form of vitamin D synthesized in the skin upon sunlight exposure, essential for calcium metabolism and bone health.
Things worth knowing about "calciferol d3"
Calciferol D3 (cholecalciferol) is the natural form of vitamin D synthesized in the skin upon sunlight exposure, essential for calcium metabolism and bone health.
What is Calciferol D3?
Calciferol D3, also known as cholecalciferol or vitamin D3, is a fat-soluble compound belonging to the secosteroid family. It is the biologically activatable precursor (prohormone) of active vitamin D. In the body, calciferol D3 is first converted in the liver to 25-hydroxyvitamin D (calcidiol) and then in the kidneys to the biologically active form calcitriol. Calciferol D3 is the form naturally produced by the human body and is also widely used in dietary supplements and fortified foods.
Biological Functions
Calciferol D3 plays a wide range of essential roles in the human body:
- Calcium and phosphate metabolism: Promotes intestinal calcium absorption and regulates blood calcium levels.
- Bone mineralization: Essential for building and maintaining strong bones and teeth.
- Muscle function: Supports normal muscle strength and coordination.
- Immune system: Modulates both innate and adaptive immune responses.
- Cell growth and differentiation: Involved in regulating the cell cycle.
- Cardiovascular and nervous system: Potential protective functions currently under active research.
Dietary Sources
The body can synthesize calciferol D3 when the skin is exposed to adequate UV-B radiation. Dietary sources that provide relevant amounts include:
- Fatty fish (salmon, herring, mackerel, sardines)
- Cod liver oil and fish liver oils
- Egg yolks
- Liver (beef, pork, poultry)
- Fortified foods such as margarine, milk, and breakfast cereals
Recommended Intake
Official recommendations for daily intake vary by age group and organization:
- Infants (0-12 months): 10 mcg (400 IU) according to WHO guidelines
- Children, adolescents, and adults (1-70 years): 15-20 mcg (600-800 IU) according to the EFSA and national health authorities
- Older adults (over 70 years): 20 mcg (800 IU) per day
- Pregnant and breastfeeding women: 15-20 mcg (600-800 IU) per day
In cases of confirmed deficiency or for high-risk groups, higher doses may be recommended under medical supervision.
Deficiency Symptoms
A vitamin D3 deficiency can manifest in various ways:
- Muscle weakness and pain
- Bone and joint pain
- Rickets (bone deformities in children)
- Osteomalacia (bone softening in adults) and osteoporosis
- Increased susceptibility to infections
- Depressed mood and fatigue
- Hair loss
Groups at Risk of Deficiency
- Older adults with limited sun exposure
- People with darker skin tones (reduced vitamin D synthesis)
- Individuals who remain indoors for cultural or medical reasons
- Breastfed infants (breast milk contains little vitamin D)
- People with malabsorption disorders (e.g., Crohn's disease, celiac disease)
- Individuals with obesity (vitamin D is sequestered in adipose tissue)
Toxicity and Overdose
Since calciferol D3 is fat-soluble, it can accumulate in the body. Vitamin D toxicity (hypervitaminosis D) is almost exclusively caused by excessive supplementation, not by sunlight exposure or diet alone. Symptoms of overdose include:
- Nausea, vomiting, and loss of appetite
- Elevated blood calcium levels (hypercalcemia)
- Kidney complications including kidney stones
- Weakness, confusion, and cardiac arrhythmias
The Tolerable Upper Intake Level (UL) established by EFSA for adults is 100 mcg (4,000 IU) per day.
Interactions
Calciferol D3 may interact with various substances and medications:
- Calcium supplements: Concurrent use may increase the risk of hypercalcemia.
- Thiazide diuretics: May further elevate blood calcium levels.
- Corticosteroids: Inhibit vitamin D activation and promote deficiency over time.
- Cholestyramine and orlistat: Reduce the absorption of fat-soluble vitamins including vitamin D3.
- Magnesium: Required for vitamin D activation; magnesium deficiency can impair the effectiveness of calciferol D3.
References
- European Food Safety Authority (EFSA): Dietary Reference Values for Vitamin D. EFSA Journal, 2016;14(10):4547.
- Holick MF et al. - Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism, 2011;96(7):1911-1930.
- World Health Organization (WHO): Vitamin D Supplementation in Infants and Children. WHO Guidelines, 2022. www.who.int
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