Vegans can get vitamin D from three main sources: sunlight, UV-treated mushrooms, and supplements derived from lichen. Most adults need 600 IU (15 mcg) daily, rising to 800 IU after age 70. Because very few plant foods naturally contain meaningful amounts, a combination of sun exposure and supplementation is the most reliable strategy.
Sunlight: Your Body’s Built-In Source
Your skin produces vitamin D when exposed to UVB rays, and this works the same whether you’re vegan or not. Exposing bare arms and legs to midday sun (between 10 a.m. and 3 p.m.) for 5 to 30 minutes twice a week can be enough to meet your needs. The exact time depends on your skin tone. People with darker skin may need up to ten times longer than those with fair skin to produce the same amount.
Geography matters just as much. If you live at or above 40 degrees north latitude (think Boston, Madrid, or Beijing), there isn’t enough UVB radiation from November through early March to produce any vitamin D in your skin. Ten degrees farther north, in places like Edmonton or London, that “vitamin D winter” stretches from October through April. During those months, you’ll need to rely entirely on food and supplements.
UV-Treated Mushrooms
Mushrooms are the only whole, unfortified plant food that can deliver a significant dose of vitamin D, but only if they’ve been exposed to ultraviolet light. A regular portabella mushroom grown in the dark contains roughly 10 IU per 100 grams, which is negligible. The same portabella exposed to UV light for just 15 to 20 seconds jumps to around 446 IU per 100 grams. That single serving could cover most of your daily requirement.
The numbers vary widely by producer. USDA testing found UV-treated portabellas ranging from 140 IU to over 750 IU per 100 grams depending on the grower and batch. Maitake mushrooms showed even more dramatic variation: one producer’s crop contained just 4 IU per 100 grams, while another using a proprietary UV growing method delivered 2,242 IU per 100 grams.
Look for packaging that says “UV-treated” or “high in vitamin D.” You can also make your own by placing store-bought mushrooms gill-side up in direct sunlight for 15 to 60 minutes before eating them. Cooking doesn’t destroy much of the vitamin D either. Grilled UV-treated portabellas retained the majority of their content in USDA testing. One thing to note: mushrooms produce vitamin D2 rather than D3. Both forms raise your blood levels, though D3 appears to be somewhat more effective at doing so.
Fortified Foods
Many plant milks (soy, oat, almond), orange juices, and breakfast cereals are fortified with vitamin D. A typical serving of fortified plant milk provides around 100 to 120 IU. That helps, but you’d need five or six glasses a day to hit 600 IU from fortified milk alone. Fortified foods work best as a supplement to your other sources rather than your primary strategy.
Check labels carefully. Not all brands fortify, and the type of vitamin D used varies. Some use D2 (always vegan), while others use D3 derived from lanolin (sheep’s wool), which isn’t vegan. A growing number of brands now use lichen-based D3, but the label won’t always specify the source.
Vegan Vitamin D Supplements
For most vegans, a daily supplement is the simplest way to ensure consistent intake, especially during winter months. You have two options: D2 supplements (derived from yeast or fungi) and D3 supplements derived from lichen. Lichen-based D3 is chemically identical to the cholecalciferol your skin makes in sunlight and to the D3 found in animal-derived supplements. Your body processes both the same way.
Research suggests D3 is more effective than D2 at raising and maintaining blood levels of vitamin D. If you’re choosing between the two, lichen-derived D3 is the stronger option. Both are widely available and clearly labeled as vegan.
Vitamin D is fat-soluble, meaning your body absorbs it better when you take it with a meal that contains some fat. Pairing your supplement with avocado, nuts, seeds, or a meal cooked in olive oil helps your gut absorb more of it. Taking a supplement on an empty stomach means some of it passes through without being used.
D2 vs. D3: Which Form Is Better?
Both vitamin D2 and D3 raise your overall vitamin D levels and serve the same function in the body. The practical difference is that D3 tends to raise blood levels more effectively and maintain them longer. For someone who is already deficient, D3 may correct the deficiency faster. For someone maintaining adequate levels with daily supplementation, the gap between the two forms is smaller.
If you’re using UV-treated mushrooms as a primary food source, you’re getting D2. That’s fine, especially when combined with sun exposure. If you’re relying heavily on supplements, choosing a lichen-based D3 gives you a slight edge.
How Much You Actually Need
The recommended daily amount set by the National Academies of Sciences, Engineering, and Medicine is 600 IU (15 mcg) for everyone aged 1 through 70, including during pregnancy and lactation. Adults over 70 need 800 IU (20 mcg). Infants under 12 months have an adequate intake of 400 IU (10 mcg).
These are minimums to prevent deficiency, and many health professionals suggest aiming higher, particularly if you have darker skin, limited sun exposure, or live at a northern latitude. The tolerable upper limit for adults is 4,000 IU per day, so there’s a wide safety margin between the recommended amount and the level that could cause harm.
Checking Your Levels
A simple blood test called a 25-hydroxy vitamin D test measures your current status. Most experts consider 20 to 40 ng/mL (50 to 100 nmol/L) an adequate range, though some recommend aiming for 30 to 50 ng/mL (75 to 125 nmol/L). If you’ve been vegan for a while and haven’t supplemented, it’s worth getting tested to see where you stand. Knowing your baseline helps you decide whether a standard 600 IU supplement is enough or whether you need a higher dose to correct a deficiency first.
Putting It Together
A realistic vegan vitamin D plan combines two or three of these sources. During summer months, regular midday sun exposure on bare skin twice a week can cover a large share of your needs. Year-round, a daily lichen-based D3 supplement of 600 to 1,000 IU provides a reliable baseline. Adding UV-treated mushrooms and fortified plant milks when available gives you extra coverage without any effort.
The vegans most at risk for deficiency are those living at northern latitudes who don’t supplement, have darker skin, or spend most of their time indoors. If that describes you, a supplement isn’t optional. It’s the single most effective change you can make.