Vitamin D
Cholecalciferol (vitamin D3)
Vitamins. Modern nutrition.
Also called Calciferol, Cholecalciferol (D3), Ergocalciferol (D2), Sunshine vitamin
Pinyin: wéishēngsù D
Spanish: Vitamina D
Too much raises calciumA fat-soluble vitamin the body makes in the skin from sunlight. It helps the gut absorb calcium and keeps bones strong.
Did you know? Vitamin D works more like a hormone than a classic vitamin. Its active form switches hundreds of genes on or off, and almost every cell has a receptor for it.
What it may help, and how strong the proof is
- Bones. Vitamin D helps the body absorb calcium. Low vitamin D causes rickets in children and soft bones in adults, and vitamin D corrects both. In some older adults, vitamin D with calcium lowers fractures, though the effect is modest.Strong proof
- Colds, flu & immunity. A large review found that vitamin D pills slightly lowered some respiratory infections, mostly in people who were low. The results are not strong enough for a clear recommendation. Trials in COVID-19 have not shown a clear benefit.Early proof
- Low mood. Low vitamin D is linked to depression in observational studies. Trials of vitamin D pills for depression have been small and mixed.Early proof
- Heart health. The VITAL trial gave vitamin D to healthy adults and did not find fewer heart attacks, strokes or cancers overall.Not supported
Parts of the body
Traditional use
Cod liver oil was given to children in Europe and North America in the 1800s and early 1900s to prevent rickets, a bone-softening disease. Fatty fish and sun exposure were the traditional sources in northern cultures.
How it is classified
- Herbal actions
- Nutritive, Hormone balancer. Energy: neutral.
How people take it
Adults ages 1 to 70 need 600 IU (15 mcg) a day, and adults 71 and older need 800 IU (20 mcg) a day (RDA). The upper limit is 4,000 IU (100 mcg) a day from food and pills. Doctors may give much higher doses for a short time to correct a clear deficiency, with blood tests to check progress.
Food, oil, capsule and tablet.
Where to get it
Good sources are fatty fish such as salmon, mackerel, sardines and herring, cod liver oil, egg yolks, and fortified milk, orange juice, plant milks and cereals. UV-exposed mushrooms also contain it. Skin makes most of it from sunlight, which depends on season, latitude, skin tone and sunscreen. Pills come as D3 (cholecalciferol) or D2 (ergocalciferol), and D3 is generally preferred.
Be careful
Vitamin D is safe at standard doses. Taking far above the upper limit for months can raise blood calcium, causing nausea, weakness, confusion, kidney stones and kidney damage. People with sarcoidosis, hyperparathyroidism, or kidney disease should check with a doctor first.
Avoid if: high blood calcium; sarcoidosis; kidney stones; hyperparathyroidism.
Mixing with other things
- Works well together
Vitamin D helps the gut absorb calcium, so the two are often taken together.
- Works well together
The body needs magnesium to turn vitamin D into its active form.
- Works well together
Vitamin K helps direct calcium into bone. The evidence is still developing.
- Use cautionWater pills (furosemide, hydrochlorothiazide)
Thiazide water pills raise blood calcium. Adding high-dose vitamin D can push calcium too high.
Found in these formulas
Bone trio (Modern)
The honest take
Vitamin D is needed for bones, and low levels are common. Pills help people who are low. For healthy adults, large trials did not show fewer heart attacks, strokes or cancers, so claims for mood, colds and COVID-19 go beyond the proof.