Vitamin D is a fat-soluble vitamin that plays a central role in calcium absorption and bone mineralization, making it essential for maintaining skeletal health throughout life. Available primarily as D2 (ergocalciferol, plant-derived) and D3 (cholecalciferol, animal-derived or synthesized via sun exposure), it functions more like a hormone once converted to its active form in the body. Research suggests that adequate vitamin D status may support immune function, mood regulation, muscle strength, and respiratory health, while studies indicate that low levels have been associated with increased risks related to cardiovascular health, certain cancers, and complications during pregnancy. Because many people have limited sun exposure or dietary intake, vitamin D has become one of the most widely studied and commonly supplemented nutrients in modern nutrition research.
Compare this supplementResearch suggests that vitamin D plays a well-established and foundational role in bone health, with studies indicati...
View studies →Research suggests that vitamin D may be associated with reduced risk for several cancers, with the most consistent ev...
View studies →Research suggests that vitamin D plays a meaningful role in cardiovascular health through several biological pathways...
View studies →Research suggests that vitamin D plays a meaningful role in regulating immune function, with studies consistently sho...
View studies →Research suggests that vitamin D plays a meaningful role in skeletal muscle function, with a 2023 systematic review f...
View studies →Research suggests that vitamin D plays a recurring role in nutrient absorption contexts, appearing across studies exa...
View studies →Research suggests that vitamin D plays a meaningful role in respiratory health, with a 2009 review highlighting assoc...
View studies →The studies provided in this reference set do not directly investigate vitamin D supplementation as a standalone inte...
View studies →The studies provided in this collection do not contain research on Vitamin D and pregnancy support — the linked liter...
View studies →St. John's Wort may increase vitamin D metabolism, potentially reducing its effectiveness.
View details →Very high doses of preformed vitamin A (retinol) may interfere with vitamin D function.
View details →Vitamin K2 helps direct calcium (absorbed via vitamin D) into bones and away from arteries.
View details →Magnesium is required for vitamin D activation and metabolism.
View details →Vitamin D significantly enhances calcium absorption from the gut.
View details →Zinc supports vitamin D receptor function and both are important for immune health.
View details →These are commonly referenced dosage ranges for this supplement. They are not medical recommendations. Always consult a healthcare provider before supplementing.
| Form | Dose range | Frequency | Studied for | Source |
|---|---|---|---|---|
| Capsule | 1,000–2,000 IU | Daily | Bone health, immune function, mood support, and muscle function in adults | Widely used dose range in RCTs for deficiency prevention and general health outcomes |
| Capsule | 50,000 IU | Weekly | Clinical correction of moderate-to-severe vitamin D deficiency | Standard clinical protocol for deficiency repletion; commonly prescribed in observational and intervention studies |
| Capsule | 400–800 IU | Daily | General health, bone health maintenance, and recommended dietary allowance for adults | Aligns with RDA established by Institute of Medicine; common in general supplementation trials |
| Capsule | 4,000–5,000 IU | Daily | Vitamin D deficiency repletion, immune function, and pregnancy support | Used in deficiency correction studies and pregnancy trials including Hollis et al. RCTs |
| Capsule | 2,000–4,000 IU | Daily | Vitamin D insufficiency correction, respiratory health, cancer risk reduction, and heart health | Common in clinical trials targeting insufficient or deficient populations; used in VITAL trial |
| Liquid | 400–1,000 IU | Daily | Bone health, immune function, and nutrient absorption in infants and young children | American Academy of Pediatrics recommendation; used in infant supplementation RCTs |