Vegans can maintain healthy vitamin D levels through a combination of regular sun exposure, UV-treated mushrooms, fortified plant milks, and supplements, though getting there takes more deliberate effort than it does for people who eat fish, eggs, or dairy. A systematic review found that average blood levels of vitamin D tend to be lower in vegans than in meat-eaters, and the prevalence of outright deficiency can reach as high as 67% in vegan groups compared with 0–6% in omnivores and pescatarians.1PubMed Central. Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review – Section: Micronutrients That gap is real, but it is entirely closeable once you understand the three main routes and a few practical details about each one.
Why Vegans Start at a Disadvantage
Most dietary vitamin D in Western diets comes from fatty fish, egg yolks, and fortified dairy products. Remove all of those and you lose the majority of the food-based supply in one move. The systematic review noted above found that vegans averaged blood levels around 21.9 µg/L, compared with 26.2 µg/L in meat-eaters, and that roughly a quarter of both vegans and vegetarians were vitamin D insufficient.1PubMed Central. Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review – Section: Micronutrients A study of Asian vegans and omnivores found the imbalance even more dramatic, with vitamin D insufficiency in 73% of vegans versus 46% of omnivores.2European Journal of Clinical Nutrition. Vegetarianism, bone loss, fracture and vitamin D: a longitudinal study in Asian vegans and non-vegans
This matters beyond just a number on a lab report. Vitamin D receptors sit on B cells, T cells, and other immune cells, and those cells can produce the active form of the vitamin themselves, meaning vitamin D directly shapes how your immune system responds to threats.3PubMed Central. Vitamin D and the immune system Low levels have also been linked to reduced bone mineral density, and an analysis of 13 studies found that vegetarians and vegans face a higher risk of osteopenia, osteoporosis, and fractures.4PubMed. The influence of vegetarian and vegan diets on the state of bone mineral density in humans The good news is that all of this risk traces to intake, not to anything inherent about plant-based eating. Close the intake gap and you close the health gap.
Sun Exposure Is Your Biggest Free Source
Your skin manufactures vitamin D3 when UVB radiation hits a cholesterol compound called 7-dehydrocholesterol, converting it into a precursor that quickly becomes vitamin D3.5PubMed Central. Sunlight and Vitamin D: A global perspective for health This is the same form of D3 found in animal foods, produced right inside your own body, which makes sun exposure the most “natural” vitamin D source for everyone, vegans included.
The catch is that dozens of variables determine how much D3 your skin actually produces. Latitude matters enormously: if you live above roughly 37°N (think San Francisco, Athens, or Seoul), winter UVB levels drop so low that meaningful skin synthesis pauses for months. Skin pigmentation plays a role too. Darker skin can block up to 95% of UVB from reaching the deeper layers where vitamin D is produced, an evolutionary adaptation that protected people near the equator from excessive vitamin D production and UV damage.6PubMed. Skin-pigment regulation of vitamin-D biosynthesis in man Time of day, cloud cover, sunscreen use, clothing, and age all shift the equation further.
A practical rule of thumb: exposing your forearms and face to midday sun for around 10 to 30 minutes, several times per week, during months when your shadow is shorter than you are, is usually enough for lighter-skinned people at mid-latitudes. Darker-skinned individuals often need significantly more time. But relying on sunlight alone is unrealistic for many people, especially those who live in northern climates, work indoors, or cover most of their skin for cultural or personal reasons. Treat the sun as a valuable bonus rather than your sole strategy.
Vegan Food Sources That Actually Move the Needle
If you search online, you will find long lists of plant foods said to contain vitamin D. In practice, only two categories deliver meaningful amounts: UV-exposed mushrooms and fortified foods.
UV-Treated Mushrooms
Mushrooms contain ergosterol, a compound that converts to vitamin D2 when hit with UV light, much like the process that happens in human skin with D3.7PubMed Central. Photobiology of vitamin D in mushrooms and its bioavailability in humans Common button mushrooms (Agaricus bisporus) are especially rich in ergosterol, and UV treatment ramps up their vitamin D2 content substantially.8PubMed. Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation Some grocery stores now sell mushrooms labeled “high in vitamin D” or “UV-treated.” You can also do this at home by placing sliced mushrooms gill-side up in direct sunlight for 15 to 60 minutes before cooking.
There is a limitation, though. Mushrooms produce D2, not D3, and as we will see in the supplements section, D2 is less potent at raising your blood levels. UV-treated mushrooms are a useful addition to your diet, but they are unlikely to single-handedly solve a deficiency.
Fortified Plant Milks and Other Products
Most commercial soy, oat, and almond milks are fortified with vitamin D, along with some cereals, orange juices, and margarines. The amount per serving is modest, typically providing a fraction of the daily recommended intake per glass. There is an interesting complication here, too: an in vitro digestion study found that high levels of added calcium in fortified almond milk can actually reduce vitamin D bioaccessibility, because the calcium forms insoluble soaps in the small intestine that trap the vitamin D.9PubMed. Fortification of Plant-Based Milk with Calcium May Reduce Vitamin D Bioaccessibility: An In Vitro Digestion Study This does not mean fortified plant milks are useless, but it does mean that fortified calcium and fortified vitamin D in the same product may not deliver as much D as the label implies.
Relying on fortified foods alone to cover your full vitamin D needs is a tall order. You would need to consume multiple servings of fortified products daily, and even then the amounts often fall short. Think of these foods as a helpful baseline, not a complete solution.
Supplements and the D2 Versus D3 Question
For most vegans, a supplement is the most reliable way to keep vitamin D levels in a healthy range, especially during winter. But the choice between vitamin D2 and vitamin D3 matters more than many people realize.
Vitamin D2 (ergocalciferol) comes from fungi and is traditionally the “vegan” form. Vitamin D3 (cholecalciferol) has historically come from lanolin in sheep’s wool or from fish oil, making it non-vegan by default. The problem is that D2 is substantially less effective at raising and maintaining blood levels of 25-hydroxyvitamin D, the standard marker of your vitamin D status. One study found that D2’s potency was less than one-third that of D3, with a much shorter duration of action. After an initial similar rise in the first three days, blood levels fell rapidly in the D2 group while continuing to climb in the D3 group.10PubMed. Vitamin D2 is much less effective than vitamin D3 in humans Another trial giving daily doses over 12 weeks found that the D3 group achieved steady-state blood levels nearly twice as high as the D2 group.11The Journal of Clinical Endocrinology & Metabolism. Vitamin D3 Is More Potent Than Vitamin D2 in Humans Clinical data from a primary-care setting confirmed this pattern, showing that D3 injections raised serum concentrations by roughly double the amount D2 injections did.12PubMed Central. Effectiveness of vitamin D2 compared with vitamin D3 replacement therapy in a primary healthcare setting: a retrospective cohort study
This used to leave vegans stuck choosing between a less effective supplement and a non-vegan one. That has changed. Vegan vitamin D3 is now widely available, sourced from lichen, a composite organism made up of fungi and algae. One study examining a lichen-based vitamin D3 pill reported that it was absorbed at a higher rate than conventional vitamin D.13International Journal of Biomedical Investigation. Formulation of Lichen Based Pill a Natural Source of Vitamin D3 with a High Absorption Rate by Ambrosiya Neo-Medicine Pvt. Ltd Lichen-derived D3 supplements are now sold by most major supplement brands. If you see “vegan D3” on a label, it almost certainly comes from lichen.
Researchers are also exploring microalgae as a vegan D3 source. Certain species produce vitamin D3 when exposed to UVB light, with one freshwater microalga (Nannochloropsis limnetica) generating particularly high concentrations.14Algal Research. UVB exposure stimulates production of vitamin D3 in selected microalgae This is still emerging technology, but it points toward a future where vegan D3 could come from multiple sustainable sources.
Getting More Out of What You Take
Popping a supplement on an empty stomach is not ideal. Vitamin D is fat-soluble, meaning it needs dietary fat present in the gut for your body to absorb it well. One controlled study found that taking a vitamin D3 dose with a meal containing fat increased absorption by about 32% compared with taking it with a fat-free meal.15PubMed. Dietary Fat Increases Vitamin D-3 Absorption Interestingly, the type of fat did not seem to matter much. Another study examining the same question found higher short-term absorption when the supplement was taken with a low-fat meal rather than a high-fat meal or no meal, though the longer-term blood levels evened out regardless of meal conditions.16PubMed. Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation The practical takeaway is simple: take your vitamin D supplement with food that contains some fat. For vegans, that could be avocado toast, a handful of nuts, or stir-fried vegetables with oil.
Magnesium also deserves attention. All the enzymes that convert vitamin D into its active form in your liver and kidneys require magnesium as a cofactor.17PubMed. Role of Magnesium in Vitamin D Activation and Function If your magnesium intake is low, supplementing with vitamin D may not translate into better blood levels as efficiently. Fortunately, many plant foods are rich in magnesium: dark leafy greens, nuts, seeds, beans, and whole grains. If you eat a varied vegan diet, you are probably doing fine on magnesium. But if your diet is heavy on processed vegan foods and light on whole plants, it is worth checking.
Vitamin K and the Bone Health Connection
Vitamin D promotes the production of certain proteins that help direct calcium into bones and teeth. These proteins need vitamin K to be activated, which is why researchers have found that combining vitamins D and K appears more effective for bone and cardiovascular health than taking either alone.18PubMed Central. The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review A trial in postmenopausal women with osteoporosis found that the group receiving both vitamins D3 and K2 showed significantly greater gains in lumbar spine bone density than groups receiving either vitamin alone or calcium alone.19PubMed. Effect of combined administration of vitamin D3 and vitamin K2 on bone mineral density of the lumbar spine in postmenopausal women with osteoporosis
This is useful news for vegans, because vitamin K1 is abundant in leafy greens like kale, spinach, and broccoli. Vitamin K2 is trickier on a vegan diet, found mainly in fermented foods like natto (fermented soybeans), certain fermented vegetables, and some vegan K2 supplements. Since bone health is a documented concern for vegans who do not supplement appropriately, paying attention to the D-K partnership is a practical way to protect your skeleton.
Vegan Children and Other Special Populations
The stakes for vitamin D are higher during certain life stages. Growing children need adequate vitamin D for proper bone development, and guidelines for vegan complementary feeding recommend supplementing infants and young children with 10 µg per day (400 IU) of vitamin D.20PubMed Central. Toward Supplementation Guidelines for Vegan Complementary Feeding This is actually the same recommendation that many pediatric bodies make for all breastfed infants regardless of diet, since breast milk is naturally low in vitamin D. Vegan parents should simply ensure they follow through consistently.
Pregnant and breastfeeding women need to be especially attentive, as their vitamin D status directly influences the baby’s stores. Older adults also face compounding challenges: skin produces less vitamin D with age, indoor time tends to increase, and kidney function (which is needed to activate vitamin D) declines. If you are vegan and over 65, a daily supplement is essentially non-negotiable unless you are getting regular sun exposure in a climate that provides it year-round.
Why Your Test Results Might Be Confusing
If you have had your vitamin D levels checked and found confusing or contradictory results, you are not alone. The blood test for vitamin D status measures 25-hydroxyvitamin D, but the methods laboratories use to run this test vary widely. One study comparing different labs found strikingly different results from nearly identical patient groups: one lab classified 17% of its samples as insufficient, while another classified 90% as insufficient, largely because the labs used different measurement methods.21The American Journal of Clinical Nutrition. Blood biomarkers of vitamin D status – Section: Which assay platform should be used? Independent researchers have confirmed that between-laboratory differences in 25-hydroxyvitamin D measurement persist and can meaningfully affect clinical decision-making.22The Journal of Clinical Endocrinology & Metabolism. Correlation among 25-Hydroxy-Vitamin D Assays
What this means for you: a single borderline result does not necessarily mean you are fine or that you are deficient. If you get a reading that does not match how you feel or what you would expect given your sun exposure and supplementation, consider getting retested through a different laboratory or asking your provider about the assay method used. The trend over multiple tests matters more than any one snapshot.
Genetics and Individual Variation
Two people on identical diets, taking the same supplement, getting the same amount of sun, can end up with meaningfully different vitamin D blood levels. Genetic variation is a significant and underappreciated contributor to these differences.23PubMed Central. Genetic Variants Influencing Individual Vitamin D Status Variations in genes that control vitamin D synthesis in the skin, transport through the blood, and breakdown in the liver and kidneys all influence how efficiently your body handles the vitamin. Population-specific allele frequencies add another layer, meaning that the ideal supplementation dose for one person may be insufficient for another.
This is not something most people need to act on with genetic testing. But it helps explain why some vegans feel great on 1,000 IU per day while others need 2,000 or more to reach the same blood level. If you have been supplementing consistently and your levels still look low, genetics may be part of the answer, and talking to a healthcare provider about adjusting your dose is reasonable.
A Practical Vegan Vitamin D Routine
Pulling all of this together into daily life does not need to be complicated. The core strategy has three layers:
- Sunlight: Get outdoors during midday hours when UVB is strong, especially in spring through fall. Even 15 minutes of face and arm exposure a few times a week contributes meaningfully. During winter months at higher latitudes, do not count on the sun for much.
- Food: Include UV-treated mushrooms when available, and drink fortified plant milks or eat fortified cereals regularly. These help maintain a baseline but rarely cover your full needs alone.
- Supplement: Take a vegan D3 supplement (lichen-sourced) daily, with a meal that includes some fat. For most adults, 1,000 to 2,000 IU per day is a common maintenance dose, though your provider may recommend more if you are correcting a deficiency.
Immune cells throughout your body carry receptors for vitamin D and can produce its active form locally, which means adequate levels do not just protect your bones but support immune function at a fundamental level.24PubMed. A review of the critical role of vitamin D axis on the immune system For vegans who have removed the dietary sources that most people rely on by default, being intentional about replacing that supply through sun, food, and a well-chosen supplement is one of the most impactful health habits you can build.