Vitamin D is the awkward nutrient: your body makes it from sunlight, almost no food naturally contains it, and the amount of sun you need is something even NIH describes with visible hesitation. This page gives the target, the upper limit, the blood thresholds doctors use, and the short list of foods that genuinely carry it.
The short version
- RDA: 15 mcg (600 IU) a day for adults 19–70; 20 mcg (800 IU) over 70.
- Upper limit: 100 mcg (4,000 IU) a day for adults.
- Few foods naturally contain it. Fatty fish and fish liver oils are the best sources; most of the rest is fortification.
- Blood thresholds: deficiency below 30 nmol/L (12 ng/mL), adequate at 50 nmol/L (20 ng/mL) or above.
- Sun advice exists but comes wrapped in stated uncertainty — and skin cancer risk is a separate conversation.
How much you need
NIH’s Office of Dietary Supplements sets the RDA at 15 mcg (600 IU) for adults up to 70, rising to 20 mcg (800 IU) after that. The Tolerable Upper Intake Level for adults is 100 mcg (4,000 IU) a day.
Note the gap between those two numbers — the recommended amount is about a sixth of the ceiling. High-dose supplements sold at 5,000 or 10,000 IU sit above the upper limit, which is a decision for a clinician with your blood results, not for a shelf.
What your blood level means
This is the one nutrient where a specific test is routine, so the numbers are worth knowing. ODS uses serum 25(OH)D thresholds of below 30 nmol/L (12 ng/mL) for deficiency, 50 nmol/L (20 ng/mL) or above for adequacy, and flags above 125 nmol/L (50 ng/mL) as a level where adverse effects become a concern. All three from the ODS vitamin D fact sheet.
That top threshold matters more than people expect: with vitamin D, more is not simply better, and the range between adequate and excessive is not enormous.
The food list is genuinely short
ODS states it directly: few foods naturally contain vitamin D. The flesh of fatty fish (such as trout, salmon, tuna, and mackerel) and fish liver oils are among the best sources.
The fortified staples that do most of the work, with full numbers: nonfat milk, fortified orange juice and white button mushrooms.
What that means practically: the fatty fish on the list does most of the work, and nearly everything else on a supermarket shelf carrying vitamin D has had it added. Fortified milk, fortified cereals and fortified plant drinks are the reason most people get any at all.
Foods with cards here: salmon, tuna, egg yolk, milk, fortified soy drink. Our cards carry calories and macronutrients from named USDA records; for vitamin D amounts per serving, the ODS fact sheet linked above is the source to use.
Seafood is also the food group USDA says Americans under-eat generally — see the documented shortfalls. Two fish meals a week does two jobs at once.
Sunlight, and why the guidance hedges
Read the hedges rather than the number. “Approximately”, “5 to 30” — a sixfold range — “usually”, and ODS’s own acknowledgement of uncertainties about the amount of sun exposure needed. Latitude, season, skin tone, age and cloud cover all move it. This is not a prescription you can follow precisely, and it sits against skin cancer guidance pulling the other way.
Who actually runs short
The at-risk groups ODS names are specific: breastfed infants, older adults, people with limited sun exposure, people with darker skin, people with fat malabsorption conditions, and people with obesity or who have had gastric bypass surgery.
Two of those are worth expanding. Fat malabsorption matters because vitamin D travels with dietary fat — ODS notes that drugs blocking fat absorption such as orlistat can decrease the absorption of vitamin A, other fat-soluble vitamins, and beta-carotene. And darker skin needs more UV exposure for the same synthesis, which interacts badly with living at high latitude.
What we are not claiming
- That you must eat vitamin D with fat. Widely repeated, but the ODS vitamin D page does not state a fat requirement for its absorption specifically. We are not extending the vitamin E statement to it.
- Vitamin D amounts for specific foods. Our cards do not carry vitamin D values; we are not inventing per-serving figures.
- That vitamin D supplements prevent disease. That is a live research question well beyond what we can source here.
- A sun exposure recommendation. We quote ODS’s figure with its own hedges, and we are not turning a 5–30 minute range into advice.
- That everyone should be tested. No source we could reach recommends population-wide screening.
FAQ
How much vitamin D per day? 600 IU for adults 19–70, 800 IU after 70, with an upper limit of 4,000 IU.
Which foods have vitamin D? Very few naturally — fatty fish such as trout, salmon, tuna and mackerel, plus fish liver oils. Most other sources are fortified.
What blood level is too low? Below 30 nmol/L (12 ng/mL) is deficiency; 50 nmol/L (20 ng/mL) or above is adequate.
Can I get enough from the sun? Possibly, but the guidance itself carries a sixfold range and explicit uncertainty, and it varies with latitude, season and skin tone.
Is more vitamin D better? No. Above 125 nmol/L (50 ng/mL) is flagged as a level where adverse effects become a concern.
What to do with this
If you are in one of the risk groups — limited sun, darker skin at high latitude, older, malabsorption, post-bariatric surgery — this is a nutrient worth testing rather than guessing about. Otherwise, two fatty-fish meals a week plus fortified foods covers most people, and any supplement above 4,000 IU should be a clinician’s decision.
Related: how supplements are regulated, iron and absorption.
Educational content, not medical advice.
This content is for educational purposes only and is not medical advice. Always consult a qualified healthcare professional for personalised guidance.
