Vegans need to supplement at least vitamin B12, and most will benefit from adding vitamin D, omega-3s, and iodine. Beyond those core four, several other nutrients deserve attention depending on your diet, activity level, and life stage. Here’s what the evidence says about each one and how to get the doses right.
Vitamin B12: The Non-Negotiable
There is no reliable plant source of vitamin B12. Studies consistently find that 50 to 70 percent of vegans have subnormal B12 status, and one European study found deficiency rates as high as 92 percent among vegans compared to 11 percent in omnivores. This isn’t a nutrient you can get from eating well-planned whole foods. You need a supplement or heavily fortified foods, period.
The U.S. recommendation is 2.4 micrograms per day for adults, while European authorities set it higher at 4 micrograms. Many practitioners suggest even larger doses (250 to 1,000 micrograms daily) because absorption from supplements is limited, especially in a single dose. Look for cyanocobalamin rather than methylcobalamin. Despite marketing claims that methylcobalamin is the “active” form, your body breaks down both forms during absorption and rebuilds them internally. A study of 42 vegans found that cyanocobalamin maintained significantly higher blood levels of active B12 than methylcobalamin did, likely because methylcobalamin is less chemically stable and degrades from light exposure.
Vitamin D: Choose D3 Over D2
Vitamin D is difficult to get from any diet, vegan or not. Your skin produces it from sunlight, but if you live above roughly 37 degrees latitude, spend most of your time indoors, or have darker skin, you likely need a supplement. The standard recommendation is 600 to 1,000 IU daily, though some people need more based on blood testing.
You’ll find two forms on shelves: D2 (ergocalciferol) and D3 (cholecalciferol). D3 is roughly twice as effective at raising blood levels as D2, even when D2 is given at double the dose. Traditional D3 comes from sheep’s wool lanolin, but vegan D3 derived from lichen is now widely available and works identically. If a supplement just says “vitamin D” without specifying D3, it’s usually D2, so check the label.
Omega-3s: Why Flax Alone Falls Short
Flaxseed, chia seeds, and walnuts supply ALA, a plant-based omega-3. The problem is that your body converts very little ALA into the long-chain omega-3s (EPA and DHA) that support brain and heart health. Estimates range from 5 to 10 percent conversion to EPA and under 5 percent to DHA, with some researchers putting the DHA conversion rate closer to 1 percent in adults.
Including a tablespoon of ground flaxseed or chia daily is still a good habit for general nutrition, but it won’t give you meaningful amounts of DHA. Algae-based omega-3 supplements, the same source that fish get their DHA from, provide 200 to 300 milligrams of combined DHA and EPA per capsule. One daily is a reasonable baseline for most adults.
Iodine: A Small Dose With a Narrow Window
Omnivores get most of their iodine from dairy, seafood, and iodized salt. Vegans who don’t cook with iodized salt can easily fall short. The recommended intake is 150 micrograms per day for adults and 250 micrograms during pregnancy.
A supplement containing 150 micrograms of potassium iodide is the safest route. Avoid kelp-based iodine supplements. Seaweed has wildly variable iodine content that can deliver up to a hundred times the daily recommendation, and a U.S. survey of kelp supplements found that many contained far more iodine than their labels claimed, sometimes exceeding the tolerable upper limit of 1,000 micrograms per day. Too much iodine disrupts thyroid function just as too little does, so this is one nutrient where precision matters more than generosity.
Calcium: Absorption Matters More Than Totals
The daily calcium target for most adults is 1,000 milligrams, and vegans can meet this through food, but only if they choose the right sources. Calcium absorption from plants varies enormously, from under 10 percent to over 50 percent, largely depending on compounds called oxalates and phytates that bind to calcium and block absorption.
Spinach is the classic trap: it’s high in calcium on paper but extremely low in bioavailable calcium because of its oxalate content. Kale, by contrast, is a standout, providing roughly five times more absorbable calcium per serving than skim milk. Broccoli, cabbage, and certain beans (chickpeas, kidney beans) are also solid sources where 1.5 to 3 servings match a glass of milk. Fortified plant milks sound like an easy fix, but research shows that the form of calcium used in many of them (tricalcium phosphate) has low solubility and poor absorption. Shake the carton well, and don’t rely on fortified beverages as your only source.
If your diet consistently falls short, a calcium supplement of 300 to 500 milligrams can fill the gap. Taking it with food and splitting the dose improves absorption.
Iron: Boosting What You Already Eat
Plant foods contain non-heme iron, which is absorbed less efficiently than the heme iron in meat. Phytates in grains, beans, and nuts, along with polyphenols in tea, coffee, and cocoa, bind to non-heme iron and reduce how much reaches your bloodstream. This doesn’t mean vegans are destined for deficiency, but it does mean strategy matters.
Vitamin C is the most powerful absorption enhancer. In one study, increasing vitamin C from 25 to 1,000 milligrams alongside a meal boosted iron absorption nearly ninefold, from 0.8 percent to 7.1 percent. You don’t need to take a megadose supplement. Around 500 milligrams of vitamin C taken with an iron-rich meal increased absorption sixfold. In practical terms, squeezing lemon over lentils or eating bell peppers with beans makes a real difference. Timing also matters: vitamin C consumed 4 to 8 hours before an iron-rich meal was significantly less effective than taking it alongside the food.
Drinking coffee or tea between meals rather than with meals also helps, since the polyphenols in those beverages are among the strongest iron absorption inhibitors. Most vegans with varied diets and good vitamin C intake maintain adequate iron levels without supplementing, but menstruating women and endurance athletes should monitor their levels with occasional blood work.
Zinc: The Quiet Shortfall
Zinc absorption faces the same phytate problem as iron. The European Food Safety Authority now sets zinc requirements at four different levels based on how much phytate is in your diet, and a diet built around whole grains, legumes, nuts, and seeds sits at the highest phytate tier. This means vegans likely need more zinc than the standard 8 to 11 milligrams per day that omnivores are told to aim for.
Soaking, sprouting, and fermenting grains and legumes reduces phytate content and improves zinc availability. If you regularly use these preparation methods, you may get enough from food. If not, a modest zinc supplement of 10 to 15 milligrams can provide insurance. Take it separately from iron supplements, since the two compete for the same absorption pathway.
Selenium: The Brazil Nut Wildcard
One or two Brazil nuts per day is often cited as the simplest way for vegans to meet selenium needs. This works, but with a caveat: selenium content in Brazil nuts varies up to eightfold from nut to nut, even within the same batch. A single 5-gram nut from a high-selenium growing region can meet or exceed the daily recommendation on its own. The tolerable upper limit is 400 micrograms per day, and toxicity symptoms (hair loss, brittle nails, gastrointestinal distress) begin around 1,200 micrograms.
Eating one to two Brazil nuts daily is a reasonable approach, but eating a handful is genuinely risky over time. If you’d rather not gamble on nut-to-nut variability, a supplement providing 55 to 100 micrograms of selenium offers more consistent dosing.
Choline: The Overlooked Nutrient
Choline supports liver function, brain health, and cell membranes, and it’s concentrated in eggs, liver, and meat. The adequate intake is roughly 550 milligrams per day for men and 425 milligrams for women. Only about 10 percent of the general U.S. population meets these targets, and vegetarians have the lowest intakes of any dietary group, averaging around 192 milligrams per day.
Tofu, quinoa, broccoli, and peanuts provide modest amounts, but reaching the full target from plant foods alone is difficult. A choline supplement or a multivitamin that includes choline can help bridge the gap, and this is especially worth considering during pregnancy, when choline needs are highest.
Creatine: Optional but Notable
Creatine is not an essential nutrient since your body produces it internally, but dietary creatine comes exclusively from meat and fish. Vegans consistently show lower muscle creatine stores than omnivores. Supplementing with creatine monohydrate (3 to 5 grams daily) has been shown to improve both physical performance and cognitive function in people with low baseline stores. If you exercise regularly or do any strength training, creatine supplementation offers more noticeable benefits for vegans than it does for meat eaters, precisely because you’re starting from a lower baseline.
Putting It All Together
- Essential for all vegans: B12 (cyanocobalamin), vitamin D3 (lichen-derived), iodine (potassium iodide, not kelp)
- Strongly recommended: Algae-based omega-3 (DHA/EPA), calcium if dietary intake is low
- Worth monitoring or supplementing: Zinc, selenium, choline, iron (especially for menstruating women)
- Performance bonus: Creatine monohydrate for active individuals
A well-chosen vegan multivitamin can cover several of these at once, but check the label carefully. Many multivitamins contain D2 instead of D3, use kelp-based iodine, or skip choline and omega-3s entirely. For most vegans, a targeted approach with individual supplements gives you better control over forms and doses.