What is Vitamin D3 (cholecalciferol)?

Vitamin D3 is a fat-soluble vitamin made in the skin from sunlight and available in supplements and some foods. It helps regulate calcium and phosphorus balance and supports multiple body systems.

What are the main benefits of Vitamin D3?

Vitamin D3 supports calcium absorption and bone mineralization, helping maintain bone strength. It also plays a role in immune regulation and may support mood, especially when levels are low.

How much Vitamin D3 should I take daily?

Common supplemental amounts range from 600 to 2000 IU per day, depending on age, sun exposure, diet, and baseline vitamin D status. A clinician can individualize dosing based on a blood test.

How do I know if I’m deficient in vitamin D?

Deficiency is confirmed with a blood test for 25-hydroxyvitamin D. Risk is higher with limited sun exposure, darker skin, older age, and certain medical conditions that affect absorption.

Can Vitamin D3 be harmful or interact with medications?

Excess vitamin D can cause high calcium levels, which may lead to symptoms like nausea, weakness, or kidney problems. Interactions are possible with some medicines, so check with a healthcare professional if you take prescription drugs or have kidney or parathyroid conditions.

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Vitamin D3

Strong study situation·10/10

A higher score indicates better study conditions, but not necessarily effectiveness.

A fat-soluble vitamin crucial for bone health, immune function, and mood regulation, widely supplemented for deficiency and overall health.

Essential Nutrient Immune Booster Bone Health Depression / Mood Enhancement

dose range

600–2000 IU

Once daily, with a meal containing fat for optimal absorption.

Consumption

Take with food (containing fat) in the morning or with first meal.

Fat-soluble: take with fat.

Best time

Splitting very high doses is not necessary in typical regimens; daily dosing preferred over large intermittent dosing for safety.

Description

Vitamin D3 (cholecalciferol) is produced in skin via sunlight and is also available as a supplement. It is essential for calcium absorption, bone mineralization, immune regulation, and plays roles in mood and general well-being. Deficiency is common, especially in regions with limited sun exposure, and supplementation is often recommended to meet health guidelines.

benefits

Main effects with level of evidence

Strong

Note on evidence

Multiple large meta-analyses and authoritative reviews confirm benefits for bone health and deficiency correction; evidence for other benefits is moderate.

Supports bone health and density

Strong

Enhances calcium and phosphorus absorption, crucial for maintaining strong bones and reducing fracture risk, especially in older adults.

Particularly relevant for: Older adults · Individuals at risk of osteoporosis · General population

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals S2 · New England Journal of Medicine: Vitamin D Supplements and Prevention of Fractures S6 · EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA): Scientific Opinion on Dietary Reference Values for vitamin D S7 · Institute of Medicine: Dietary Reference Intakes for Calcium and Vitamin D (2011)

Modulates and supports immune function

Moderate

Helps regulate immune processes and may reduce susceptibility to infections, including respiratory tract illnesses.

Particularly relevant for: Immunocompromised · General population

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals S3 · PubMed: Vitamin D and the Immune System

Supports mood and may reduce depression risk

Moderate

May aid in the regulation of mood and reduce incidence or severity of depression, especially in those with low vitamin D levels.

Particularly relevant for: Individuals with limited sun exposure · People with low vitamin D status

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals S4 · Journal of Affective Disorders: Vitamin D Supplementation and Depression in Adults

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

Vitamin D3 is generally safe at recommended doses, but excess can cause serious adverse effects.

warning notices

Excessive intake raises blood calcium, risking nausea, vomiting, confusion, kidney stones, and kidney damage.
People with certain health conditions (e.g., hyperparathyroidism, granulomatous diseases, severe kidney disease) are at increased risk of toxicity.
Routine monitoring is recommended in high-dose or long-term use, especially with interacting medications.
Avoid use in individuals with hyperparathyroidism or granulomatous diseases unless under medical supervision.
Do not exceed the tolerable upper intake level of 4000 IU daily for adults unless prescribed.
Monitor serum calcium if using vitamin D3 while on thiazide diuretics, as risk of hypercalcemia increases.
Use only with clinician oversight in individuals with a history of kidney stones or severe renal impairment.

Known interactions with medications

thiazide diuretics
corticosteroids
orlistat

Contraindications / special precautions

hyperparathyroidism
granulomatous disease
severe renal impairment
history of kidney stones

interactions

Important interactions between active ingredient ↔ supplement / medication / food

Vitamin D3 interacts with some medications and nutrients, mainly affecting calcium metabolism and absorption.

Monitor calcium levels when combining vitamin D3 with thiazide diuretics.

drug · Thiazide diuretics

MonitorStrong

Why

Both can increase serum calcium, posing a risk for hypercalcemia.

recommendation

Monitor serum calcium regularly and use under medical supervision.

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals S8 · Mayo Clinic: Vitamin D Toxicity — Symptoms and Causes

Corticosteroids may lower vitamin D absorption and increase bone loss risk.

drug · Corticosteroids

CautionModerate

Why

These drugs can impair vitamin D metabolism, increasing the risk of deficiency and osteoporosis.

recommendation

Consider monitoring vitamin D status and supplementing as needed during prolonged corticosteroid use.

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals

Orlistat may decrease vitamin D3 absorption.

drug · Orlistat

SeparateModerateSeparate by 2h

Why

Orlistat reduces fat absorption, lowering bioavailability of fat-soluble vitamins.

recommendation

Take vitamin D3 supplement at a different time of day than Orlistat.

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals

mechanisms of action

Brief explanations of how it works

Regulation of calcium and phosphorus absorption

Vitamin D3 increases the efficiency of intestinal calcium and phosphorus absorption, essential for skeletal mineralization and maintenance of bone health.

S1 · NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals S2 · New England Journal of Medicine: Vitamin D Supplements and Prevention of Fractures S7 · Institute of Medicine: Dietary Reference Intakes for Calcium and Vitamin D (2011)