Cod liver oil is the highest vitamin D food there is, at 10,000 IU per 100g in USDA food composition data. After that the list falls off a cliff. UV-exposed mushrooms and oily fish land between 550 and 1,150 IU per 100g. Everything below them is close to rounding error.
Eight foods carry the entire category. Here they are by measured dose, with the amount you would actually put on a plate.
The short version
- Cod liver oil leads at 10,000 IU per 100g. Nothing is close.
- UV-exposed mushrooms hold above 10 mcg per 100g, the best plant source.
- Farmed salmon carries roughly a quarter of wild salmon's vitamin D.
- Oven heat costs 55 to 61% of it. Frying keeps most.
- The RDA is 600 IU for adults under 71.
Foods high in vitamin D, ranked
Figures are IU per 100g from USDA FoodData Central, raw unless stated.
| Food | IU per 100g | Realistic serving |
|---|---|---|
| Cod liver oil | 10,000 | 450 IU per teaspoon |
| Mushrooms, UV-exposed | 1,050 to 1,140 | 840 to 910 IU per 80g |
| Mackerel, Atlantic | 643 | 900 IU per 140g fillet |
| Rainbow trout, farmed | 635 | 889 IU per 140g fillet |
| Salmon, sockeye | 563 | 788 IU per 140g fillet |
| Sardines, canned in oil, with bone | 193 | 183 IU per 95g tin |
| Egg, whole | 82 | 41 IU per large egg |
| Milk, fortified whole | 38 | 94 IU per cup |
1. Cod liver oil, the outlier
One teaspoon carries about 450 IU, most of a day's requirement in a single measure. It is also the only entry here that nobody eats for pleasure.
The reason it wins is anatomical. Vitamin D concentrates in fish liver rather than fish muscle, and that pattern holds across animal foods generally. A 2013 review of natural vitamin D content found the highest values in fish and fish liver, useful amounts in offal, and much lower amounts in muscle meat, with egg yolk sitting between the two (Schmid and Walther, Advances in Nutrition).
2. UV-exposed mushrooms, the only real plant source
Mushrooms make vitamin D the way your skin does. They carry a precursor, provitamin D2, and ultraviolet light converts it. A 2018 review in Nutrients found that UV-exposed mushrooms stay above 10 mcg per 100g fresh weight through storage and cooking, which is more than most foods that contain vitamin D at all (Cardwell et al.).
The form is D2 rather than D3. That matters less than the internet suggests. A Boston University group found that 2,000 IU of D2 from mushrooms raised and maintained blood 25-hydroxyvitamin D as effectively as 2,000 IU of either D2 or D3 from a supplement (Keegan et al.). Shiitake also produce small amounts of D3 and D4. We went through the D2 versus D3 argument separately.
One condition attached. Mushrooms grown in the dark, which is most of what sits in a supermarket, contain almost none. The packaging has to say UV-exposed or sun-grown.
3. Oily fish, and the farmed salmon catch
Atlantic mackerel measures 643 IU per 100g and farmed rainbow trout 635 IU (USDA). A 140g fillet of either clears 880 IU. Sockeye salmon comes in at 563 IU per 100g.
Then the problem with those numbers. When Michael Holick's lab measured actual fish instead of reading the reference tables, farmed salmon turned out to carry roughly 25% of the vitamin D in wild salmon, and content varied widely even within the same species. Their conclusion was that published vitamin D tables are out of date and need re-evaluating (Lu et al., Journal of Steroid Biochemistry and Molecular Biology). Treat every figure in this post as a central estimate for a food that varies fillet to fillet.
4. Sardines, eggs and fortified milk
Sardines canned in oil with the bones left in measure 193 IU per 100g, so a 95g tin gives about 183 IU (USDA). A large egg carries around 41 IU, all of it in the yolk. Fortified whole milk runs about 94 IU per cup.
The milk figure deserves an asterisk. The same Holick paper reported that fortified milk often fails to contain 80% of what the label states (Lu et al.). Fortification is a manufacturing step, and manufacturing steps drift.
5. What cooking takes back
Heat removes a share of it, and how much depends entirely on method. Danish researchers measured retention across ordinary household cooking and found 39 to 45% surviving 40 minutes in an oven, against 82 to 84% after pan frying and 86 to 88% in boiled eggs (Jakobsen and Knuthsen, Food Chemistry). Grilling knocks UV-exposed portabella from 1,140 IU per 100g down to 524 (USDA).
Hot and fast beats long and slow, which is the opposite of how most people cook a fillet.
Why the list is this short
Vitamin D is barely a vitamin. Humans evolved to make it in skin from sunlight, so very few foods ever accumulated much of it. That single fact explains a top-eight list where the leader is a medicinal oil and second place is a fungus that had to be put under a lamp.
The 2013 animal foods review said it plainly: with intake recommendations where they now sit, covering the requirement from foodstuffs alone is difficult (Schmid and Walther). It can be done. A 140g mackerel fillet clears the RDA by itself. It just takes oily fish most days of the week, and most people do not eat that way.
How much you actually need
The RDA is 600 IU a day for ages 1 to 70 and 800 IU from 71, set to reach a blood 25-hydroxyvitamin D of at least 20 ng/ml (Ross et al., Journal of Clinical Endocrinology and Metabolism). Worth knowing who set it: that same committee concluded the prevalence of vitamin D inadequacy in North America had been overestimated, and that higher intakes were not consistently linked to greater benefit.
The population data supports a calmer reading than the supplement aisle offers. In NHANES 2011 to 2014, 5.0% of Americans aged 1 and over were at risk of deficiency, with a further 18.3% at risk of inadequacy, and the peak sat at 7.6% in adults aged 20 to 39 (Herrick et al., American Journal of Clinical Nutrition). Europe reads worse. Across 55,844 people, 13.0% fell below 30 nmol/l averaged over the year, rising to 17.7% during October to March (Cashman et al.).
Most people are not deficient. A real minority are, and winter is when it shows.
One free improvement
Vitamin D is fat soluble and it absorbs better alongside a proper meal. Patients who simply moved their supplement to the largest meal of the day raised blood 25-hydroxyvitamin D by an average of 57% over two to three months, on an unchanged dose (Mulligan and Licata, Journal of Bone and Mineral Research). The same logic applies to the food version, which is part of why oily fish and egg yolk do well here. They arrive with their own fat.
If you are working through food sources generally, the same pattern of a few dense foods and a long tail of noise applies to potassium.
The point
A list this short tells you something. Vitamin D was always meant to come from daylight, and if you live somewhere with a real winter, daylight clocks off for half the year. Cod liver oil became a cupboard staple for a reason.
Fireblood contains 2,000 IU of vitamin D3 as cholecalciferol, alongside 120mcg of vitamin K2 as MK-4 and 100mg of magnesium, both of which vitamin D works with. It will not replace oily fish and it will not replace daylight. It covers the days you get neither. The full label sits on the product page, and we wrote about why D3 and K2 belong together if you want the reasoning.
