Vitamin D3
Commonly used for
EnergyImmunityMuscle & StrengthHeart HealthHealthy AgingFocus
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Wellness uses
Antiviral support, mood support, winter blues support, respiratory support, thyroid support, period cramp relief, fibromyalgia support, blood sugar support
This is anecdotal, and there isn't strong clinical evidence that it works for everyone.
What is it? / Overview
Vitamin D supports calcium absorption, bone strength, muscle function, and normal immune activity. Many adults have inadequate levels especially with limited sun exposure. Correcting deficiency often improves musculoskeletal health and optimizes long-term wellness.
How is it used? / Administration
Form: Vitamin D3 (cholecalciferol)
Typical dose studied: 1,000–2,000 IU/day maintenance; 2,000–4,000 IU/day for deficiency
Timing: With fat-containing meal, same time daily
D3 preferred over D2. Avoid megadoses unless medically indicated. Pair with adequate calcium when appropriate.
What does it pair with?
Pairs well with:
Adequate magnesium helps the body properly metabolize vitamin D — Magnesium participates in vitamin D metabolism; a randomized trial found magnesium plus D increased blood vitamin D levels more than D alone in overweight/obese adults, though other outcomes weren't consistently improved.
Frequently combined for bone and calcium support, but not required together — Often formulated together, but evidence doesn't establish that everyone taking vitamin D must also take K2.
How well does it work? / Evidence
✓ Well-established
Who should avoid it?
Avoid with: Hypercalcemia; Hyperparathyroidism; Sarcoidosis / Granulomatous disease
Interacts with: Thiazide diuretics; Digoxin; Orlistat may reduce absorption
Already taking it? Check total intake from multivitamins. Recheck levels after 8–12 weeks if treating deficiency.
Research & references
Holick MF. (2011). Evaluation and Treatment of Vitamin D Deficiency. Endocrine Society. Bouillon R et al. (2022). The health effects of vitamin D supplementation: evidence from human studies. Nat Rev Endocrinol. Institute of Medicine. (2011). Dietary Reference Intakes for Calcium and Vitamin D. Dibaba DT. (2019). Effect of vitamin D supplementation on serum lipid profiles: a systematic review and meta-analysis. Nutr Rev. Kim G et al. (2016). Vitamin D and atopic dermatitis: A systematic review and meta-analysis. Nutrition. Nielsen AY et al. (2024). Vitamin D Supplementation for Treating Atopic Dermatitis in Children and Adults: A Systematic Review and Meta-Analysis. Nutrients.
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