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Vitamin D3

Vitamins

Also known as: Cholecalciferol, Sunshine Vitamin

Vitamin D3 is a fat-soluble vitamin produced in the skin upon exposure to UVB sunlight. It plays a critical role in calcium absorption, bone health, immune regulation, and mood stabilization. Deficiency is extremely common, especially in northern latitudes.

Best Timing

Take with your largest meal containing fat for best absorption. Morning or afternoon preferred.

Absorption

Fat-soluble — must be taken with dietary fat. Absorption is significantly reduced on an empty stomach. Magnesium status affects conversion to active form.

Health Goals
🛡️Immunity😊Mood💪Muscle❤️Heart🧬Longevity
Who Should Take This
Vegans/VegetariansElderly (60+)Pregnant WomenHigh-Stress Individuals
  • Enhances calcium and phosphorus absorption for strong bones
  • Supports immune system function and reduces infection risk
  • May reduce risk of depression and improve mood
  • Supports cardiovascular health
  • May reduce risk of certain cancers
  • Supports healthy pregnancy outcomes
General health maintenance1,000–2,000 IU

Daily

Standard dose for adults

Deficiency correction5,000–10,000 IU

Daily for 8–12 weeks

Under medical supervision, then reduce

Immune support2,000–5,000 IU

Daily

Higher doses in winter months

Upper tolerable limit4,000 IU

Daily

Without medical supervision

  • -Cholecalciferol (D3) – preferred, more bioavailable
  • -Ergocalciferol (D2) – plant-derived, less effective
  • -Calcifediol (25-hydroxyvitamin D) – pre-converted form
Fatty fish (salmon, mackerel, sardines)Cod liver oilEgg yolksFortified milk and orange juiceMushrooms exposed to UV light
Vitamin K2Synergy

K2 directs calcium mobilized by D3 into bones and away from arteries. Always pair with K2.

MagnesiumSynergy

Magnesium is required for Vitamin D metabolism. Deficiency in Mg impairs D3 activation.

CalciumSynergy

D3 enhances calcium absorption by up to 40%. Take together for bone health.

Omega-3Synergy

Fat-soluble vitamin — taking with omega-3 (fat) improves absorption.

Vitamin ACaution

High-dose Vitamin A may antagonize Vitamin D. Balance intake of both.

Vitamin D supplementation and prevention of type 2 diabetes

Pittas AG, Dawson-Hughes B, et al. - New England Journal of Medicine (2019)

4,000 IU/day did not significantly lower diabetes risk in the overall cohort, but showed benefit in those with prediabetes.

Effect of Vitamin D3 on self-perceived fatigue

Nowak A, Boesch L, et al. - Medicine (Baltimore) (2016)

Vitamin D supplementation significantly improved fatigue scores in deficient individuals.

Vitamin D and Immune Function

Aranow C. - Journal of Investigative Medicine (2011)

Vitamin D modulates both innate and adaptive immune responses. Deficiency is associated with increased autoimmunity and susceptibility to infection.