Most adults need 600 IU of vitamin D a day, or 800 IU after 70, and should not routinely take more than 4,000 IU. Those official numbers are the place to start, but your body weight, skin tone, age and how much sun you get all shift what you actually need. Here are the guidelines, the debate around them, and how to decide what is right for you.
How much vitamin D do you need each day?
The US recommendations come from the National Academies (formerly the Institute of Medicine), which set them in 2011 assuming minimal sun exposure. The figures below are from MedlinePlus; for infants the figure is an adequate intake rather than an RDA. One microgram of vitamin D equals 40 IU.
| Age | Recommended daily intake | Upper limit per day |
|---|---|---|
| 0 to 6 months | 400 IU (10 mcg) | 1,000 IU (25 mcg) |
| 7 to 12 months | 400 IU (10 mcg) | 1,500 IU (38 mcg) |
| 1 to 3 years | 600 IU (15 mcg) | 2,500 IU (63 mcg) |
| 4 to 8 years | 600 IU (15 mcg) | 3,000 IU (75 mcg) |
| 9 to 70 years | 600 IU (15 mcg) | 4,000 IU (100 mcg) |
| Over 70 years | 800 IU (20 mcg) | 4,000 IU (100 mcg) |
| Pregnancy and breastfeeding | 600 IU (15 mcg) | 4,000 IU (100 mcg) |
The upper limit is the most you can take every day long term without expecting harm. It is not a target.
What affects how much vitamin D you need?
- Body weight. In data from 17,614 adults, people with obesity had lower blood levels for the same supplement dose, and the authors suggested two to three times more vitamin D for them. That is an estimate from observational data rather than a trial result, so discuss it with your doctor.
- Skin tone. Melanin filters UVB, so darker skin makes less vitamin D from the same amount of sun.
- Age. Aging skin makes less vitamin D, which is one reason the RDA rises after 70.
- Where you live. Above roughly 33 degrees latitude, the winter sun is too weak for your skin to make much vitamin D.
- Health and medicines. Conditions such as Crohn's or celiac disease, weight-loss surgery, kidney or liver disease and some medicines affect how much vitamin D you absorb or use.
Do some experts recommend more vitamin D?
Yes, and this is where the guidance gets less tidy. The Bone Health and Osteoporosis Foundation recommends 800 to 1,000 IU a day for people 50 and older. Some researchers argue for higher blood levels than the 20 ng/mL the National Academies considers adequate: one dosing study estimated that getting most adults above 30 ng/mL could take 3,800 to 5,000 IU a day, and traditionally living Maasai and Hadzabe people in Tanzania average about 46 ng/mL (115 nmol/L), though the authors note it is uncertain whether that level is optimal for people living a Western lifestyle.
The most recent review pulls the other way. The 2024 Endocrine Society guideline found no clear evidence for an optimal blood level and suggests against taking more than the recommended intake to prevent disease in healthy adults under 75. It does suggest supplements for children and teens, adults over 75, pregnancy and high-risk prediabetes.
What if a blood test shows you are deficient?
Then the dose is a conversation with your doctor, who may recommend a higher amount for a set period and retest to see how your levels respond. Our guide to vitamin D deficiency symptoms explains what the test numbers mean. Doctors measure 25-hydroxyvitamin D, and 20 ng/mL (50 nmol/L) or above is enough for most people.
How much vitamin D is too much?
Toxicity is rare and almost always comes from supplements, not sunlight or food. Acute toxicity probably requires more than 10,000 IU a day, pushing blood levels above 150 ng/mL, and long-term intake above 4,000 IU may carry risks of its own. Our article on vitamin D toxicity covers the symptoms.
So how much vitamin D should you take?
For most healthy adults, the goal is the RDA from sun, food and supplements combined: 600 IU a day, or 800 IU after 70. If you supplement, choose vitamin D3, which raises blood levels more than D2 (see D2 vs D3).
Our Sol Food tablets provide 2,000 IU of vitamin D3 from lichen, the same daily amount used in the VITAL trial. Sol Food High Potency provides 5,000 IU of D3 with MenaQ-7 vitamin K2. If you are pregnant or breastfeeding, have kidney disease or take prescription medicines, check with your doctor before taking any vitamin D supplement.
