Vitamin D
Also known as: Vitamin D3, Cholecalciferol, Calciferol, Sunshine Vitamin
Vitamin D is a fat-soluble vitamin that plays a crucial role in calcium absorption, bone health, immune function, and mood regulation. Unlike most vitamins, your body can produce vitamin D when your skin is exposed to sunlight, earning it the nickname 'the sunshine vitamin.'
Benefits
Essential for calcium absorption and bone health — prevents rickets in children and osteomalacia/osteoporosis in adults. Supports immune system function and may reduce risk of autoimmune diseases. Emerging research links adequate vitamin D to reduced risk of certain cancers, cardiovascular disease, and depression. Supports muscle function and may reduce fall risk in older adults.
Recommended Dosage
RDA: 600 IU (15 mcg) daily for adults 19–70; 800 IU (20 mcg) for adults over 70. Many experts recommend 1,000–2,000 IU daily for optimal levels. Upper tolerable limit: 4,000 IU daily. Higher therapeutic doses (up to 5,000–10,000 IU) may be prescribed for deficiency under medical supervision. Best absorbed when taken with a meal containing fat.
Food Sources
Fatty fish (salmon, mackerel, sardines, tuna), cod liver oil, fortified milk and orange juice, fortified cereals, egg yolks, beef liver, mushrooms exposed to UV light, fortified plant-based milk alternatives.
Side Effects
Generally well-tolerated at recommended doses. Excessive intake can cause hypercalcemia: nausea, vomiting, weakness, frequent urination, bone pain, kidney stones, and kidney damage. Chronic toxicity from mega-doses can lead to calcium deposits in soft tissues including the heart and blood vessels.
Interactions
Steroids (prednisone) may reduce calcium absorption and impair vitamin D metabolism. Orlistat and cholestyramine reduce fat absorption and therefore vitamin D absorption. Thiazide diuretics combined with vitamin D may cause hypercalcemia. Statins — some statins' efficacy may be affected. Digoxin — hypercalcemia from excess vitamin D can cause dangerous arrhythmias.
Warnings
Do not exceed 4,000 IU daily without medical supervision. People with granulomatous diseases (sarcoidosis), certain lymphomas, hyperparathyroidism, or kidney disease should consult their doctor before supplementing. Blood levels should be monitored when taking high doses. Vitamin D toxicity, while rare, can be serious.
Deficiency Symptoms
Bone pain and muscle weakness, increased risk of fractures, fatigue and general tiredness, mood changes and depression, impaired wound healing, frequent infections and illness, hair loss, weight gain. Severe deficiency can cause rickets (children) or osteomalacia (adults).
Frequently Asked Questions
What are the benefits of Vitamin D?▼
Essential for calcium absorption and bone health — prevents rickets in children and osteomalacia/osteoporosis in adults. Supports immune system function and may reduce risk of autoimmune diseases. Emerging research links adequate vitamin D to reduced risk of certain cancers, cardiovascular disease, and depression. Supports muscle function and may reduce fall risk in older adults.
What is the recommended dosage for Vitamin D?▼
RDA: 600 IU (15 mcg) daily for adults 19–70; 800 IU (20 mcg) for adults over 70. Many experts recommend 1,000–2,000 IU daily for optimal levels. Upper tolerable limit: 4,000 IU daily. Higher therapeutic doses (up to 5,000–10,000 IU) may be prescribed for deficiency under medical supervision. Best absorbed when taken with a meal containing fat.
What foods contain Vitamin D?▼
Fatty fish (salmon, mackerel, sardines, tuna), cod liver oil, fortified milk and orange juice, fortified cereals, egg yolks, beef liver, mushrooms exposed to UV light, fortified plant-based milk alternatives.
What are the side effects of Vitamin D?▼
Generally well-tolerated at recommended doses. Excessive intake can cause hypercalcemia: nausea, vomiting, weakness, frequent urination, bone pain, kidney stones, and kidney damage. Chronic toxicity from mega-doses can lead to calcium deposits in soft tissues including the heart and blood vessels.
What are the symptoms of Vitamin D deficiency?▼
Bone pain and muscle weakness, increased risk of fractures, fatigue and general tiredness, mood changes and depression, impaired wound healing, frequent infections and illness, hair loss, weight gain. Severe deficiency can cause rickets (children) or osteomalacia (adults).
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Supplement Disclaimer
This supplement information is for educational purposes only and should not replace professional medical advice. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a healthcare provider before starting any supplement, especially if you are pregnant, nursing, taking medications, or have a medical condition.