One common concern about vegan diets is whether they provide your body with all the vitamins and minerals it needs.
Many claim that a whole-food, plant-based diet easily meets all the daily nutrient requirements.
Some even encourage vegans to avoid all supplements.
Despite meaning well, this type of advice can do more harm than good.
Here are 7 nutrients that you may need to supplement with while on a vegan diet.
Foods often touted as rich in vitamin B12 include unwashed organic produce, mushrooms grown in B12-rich soils, nori, spirulina, chlorella and nutritional yeast.
Some believe vegans who eat enough of the right plant foods don't need to worry about a vitamin B12 deficiency.
However, there is no scientific basis for this belief.
Several studies show that while anyone can have low vitamin B12 levels, vegetarians and vegans have a higher risk of deficiency. This seems especially true for vegans who are not taking any supplements (1, 2, 3).
Vitamin B12 is important for many bodily processes, including protein metabolism and the formation of oxygen-transporting red blood cells. It also plays a crucial role in the health of your nervous system (4).
The daily recommended intake is 2.4 mcg per day for adults, 2.6 mcg per day during pregnancy and 2.8 mcg per day while breastfeeding (4).
The only scientifically proven way for vegans to reach these levels is by consuming B12-fortified foods or taking a vitamin B12 supplement. B12-fortified foods commonly include plant milks, soy products, breakfast cereals and nutritional yeast.
What's more, no scientific evidence supports depending on unwashed organic produce as a reliable source of vitamin B12.
Nutritional yeast only contains vitamin B12 when fortified. However, vitamin B12 is light-sensitive and may degrade if bought from or stored in clear plastic bags (14).
It's important to keep in mind that vitamin B12 is best absorbed in small doses. Thus, the less frequently you ingest vitamin B12, the more you need to take.
This is why vegans who are unable to reach the recommended daily intake using fortified foods should opt for a daily supplement providing 25–100 mcg of cyanocobalamin or a weekly dosage of 2,000 mcg.
Those weary of taking supplements may find it reassuring to get their blood vitamin B12 levels checked before taking any.
But be aware that high intakes of seaweed, folic acid or vitamin B6 can falsely inflate markers of vitamin B12. For this reason, you may want to have your healthcare practitioner evaluate your methylmalonic acid status instead (15).
Interestingly, your ability to absorb vitamin B12 decreases with age. Therefore, the Institute of Medicine recommends that everyone over the age of 51 — vegan or not — consider fortified foods or a vitamin B12 supplement (16).
Bottom Line: It's extremely important that all vegans get enough vitamin B12. The only reliable way to achieve this is by eating fortified foods or taking a vitamin B12 supplement.
The RDA for vitamin D for children and adults is 600 IU (15 mcg) per day. The elderly, as well as pregnant or lactating women, should aim for 800 IU (20 mcg) per day (22).
That said, there is some evidence that your daily requirements are actually far greater than the current RDA (23).
Unfortunately, very few foods naturally contain vitamin D, and foods fortified with vitamin D are often considered insufficient to satisfy the daily requirements.
Besides the small amount you get from your diet, vitamin D can also be made from sun exposure. Most people likely make enough vitamin D by spending 15 minutes in the midday sun when the sun is strong — as long as they don't use any sunscreen.
Furthermore, because of the known negative effects of excess UV radiation, many dermatologists warn against using sun exposure to boost vitamin D levels (28).
The best way vegans can ensure they're getting enough vitamin D is to have their blood levels tested. Those unable to get enough from fortified foods and sunshine should consider taking a daily vitamin D2 or vegan vitamin D3 supplement.
Bottom Line: Vitamin D deficiency is a problem among vegans and omnivores alike. Vegans unable to maintain normal blood levels through fortified foods and sun exposure should consider taking a supplement.
Omega-3 fatty acids can be split into two categories:
- Essential omega-3 fatty acids: Alpha-linolenic acid (ALA) is the only essential omega-3 fatty acid, meaning you can only get it from your diet.
- Long-chain omega-3 fatty acids: This category includes eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). They are not technically considered essential because your body can make them from ALA.
Getting enough ALA should theoretically maintain adequate EPA and DHA levels. However, studies report that the conversion of ALA to EPA may be as low as 5%, whereas conversion to DHA may be near 0% (37, 38).
Additionally, research consistently shows that vegetarians and vegans have up to 50% lower blood and tissue concentrations of EPA and DHA than omnivores (39).
While no official RDA exists, most health professionals agree that 200–300 mg of a supplement containing EPA and DHA per day should be sufficient (39).
Vegans can reach this recommended intake through an algae oil supplement.
Minimizing your intake of omega-6 fatty acids from oils such as corn, soy, safflower, sunflower and sesame, as well as making sure to eat enough ALA-rich foods, may further help maximize EPA and DHA levels (40).
Bottom Line: Vegans tend to have lower blood and tissue levels of long-chain omega-3 fatty acids. Therefore, they may benefit from supplementing with EPA and DHA.
Getting enough iodine is crucial for healthy thyroid function, which controls your metabolism.
An iodine deficiency during pregnancy and early infancy can result in irreversible mental retardation (41).
In adults, insufficient iodine intake can lead to hypothyroidism.
This can cause symptoms such as low energy levels, dry skin, tingling in hands and feet, forgetfulness, depression and weight gain (41).
The RDA for adults is 150 mcg of iodine per day. Pregnant women should aim for 220 mcg per day, and those breastfeeding are recommended to further increase their daily intake to 290 mcg per day (44).
Iodine levels in plant foods depend on the iodine content of the soil. For instance, food grown close to the ocean tends to be higher in iodine.
The only foods considered to have consistently high iodine levels include iodized salt, seafood, seaweed and dairy products, which pick up iodine from solutions used to clean cows and farm equipment.
Half a teaspoon (2.5 ml) of iodized salt is sufficient to meet your daily needs.
Vegans who do not want to consume iodized salt or fail to eat seaweed several times per week should consider taking an iodine supplement.
Bottom Line: Iodine plays an important role in your thyroid function and metabolism. Vegans not getting enough iodine from seaweed or iodized salt should consider taking an iodine supplement.
Iron is a nutrient used to make new DNA and red blood cells, as well as carry oxygen in the blood. It's also needed for energy metabolism (45).
Too little iron can lead to anemia and symptoms such as fatigue and decreased immune function.
The RDA is 8 mg for adult men and post-menopausal women. It increases to 18 mg per day for adult women, and pregnant women should aim for 27 mg per day (46).
Iron can be found in two forms: heme and non-heme. Heme iron is only available from animal products, whereas non-heme iron is found in plants (45).
Because heme iron is more easily absorbed from your diet than non-heme iron, vegans are often recommended to aim for 1.8 times the normal RDA. That said, more studies are needed to establish whether such high intakes are really needed (47).
Vegans with a low iron intake should aim to eat more iron-rich foods, such as cruciferous vegetables, beans, peas, dried fruit, nuts and seeds. Iron-fortified foods, such as cereals, enriched breads and some plant milks, can further help (24, 48).
Also, using cast-iron pots and pans to cook, avoiding tea or coffee with meals and combining iron-rich foods with a source of vitamin C can help boost iron absorption.
The best way to determine whether supplements are necessary is to get your hemoglobin and ferritin levels checked by your health practitioner.Unnecessary intakes of supplements such as iron can do more harm than good by damaging cells or blocking the absorption of other minerals from your gut ( 49).
Extremely high levels can even cause convulsions, lead to organ failure or coma and be fatal in some cases. Thus, it's best not to supplement unless truly necessary (50).
Bottom Line: Vegans not getting enough iron from their diets should consider fortified foods or a supplement. However, overly high levels can be harmful and iron supplements are not recommended for everyone.
Calcium is a mineral necessary for bone and teeth. It also plays a role in muscle function, nerve signaling and heart health.
The RDA for calcium is set at 1,000 mg per day for most adults and increases to 1,200 mg per day for adults over the age of 50 (51).
An often-heard remark among the vegan community is that vegans have lower calcium needs than omnivores because they do not use this mineral to neutralize the acidity produced by a meat-rich diet.
More research is currently needed to evaluate how meatless diets affect daily calcium requirements. However, there is evidence that vegans consuming less than 525 mg of calcium tend to have an increased risk of bone fractures (53).
For this reason, all vegans are encouraged to aim for the RDA, making sure they consume 525 mg of calcium per day at the very least. Supplements should be used if this cannot be achieved through diet or fortified foods alone.
Bottom Line: Vegans consuming too little dietary calcium should consider taking a daily supplement. This is especially important for those getting less than 525 mg per day.
Zinc is a mineral crucial for metabolism, immune function and the repair of body cells.
An insufficient intake of zinc can lead to developmental problems, hair loss, diarrhea and delayed wound healing.
The RDA for zinc is currently set at 8–9 mg per day for adults. It increases to 11–12 mg for pregnant women and 12–13 mg for lactating women (54).
Few plant foods actually contain zinc. Moreover, zinc absorption from some plant foods is limited due to their phytate content. For this reason, vegetarians are encouraged to aim for 1.5 times the RDA (54).
While not all vegans have low blood zinc levels, a recent review of 26 studies showed that vegetarians — and especially vegans — have lower zinc intakes and slightly lower blood zinc levels than omnivores (55).
To maximize your intake, eat a variety of zinc-rich foods throughout the day. These include whole grains, wheat germ, tofu, sprouted breads, legumes, nuts and seeds.
Vegans concerned about their zinc intake or those with symptoms of a deficiency may consider taking a daily zinc gluconate or zinc citrate supplement that provides 50–100% of the RDA.
Bottom Line: Vegans unable to reach the zinc RDA should first focus on adding zinc-rich foods to their diets. Those with low blood zinc levels should consider adding a daily supplement.
Well-planned vegan diets can fulfill nutrition needs for all stages of life.
That said, certain nutrient requirements may be difficult to achieve through diet and fortified foods alone.
This is especially true for vitamin B12, vitamin D and long-chain omega-3s.
All vegans unable to meet their dietary recommendations through diet alone should seriously consider taking supplements.