What vitamins are vegans usually deficient in?

December 5, 2025 •

4 min read

According to a 2021 review of European studies, vegans had significantly lower average daily intake of vitamin B12 and calcium compared to recommendations. Knowing what vitamins are vegans usually deficient in is the first step toward building a complete and healthy plant-based diet.

Quick Summary

A strict vegan diet may lack essential nutrients like vitamin B12, vitamin D, iodine, and easily absorbed iron and calcium, leading to potential health risks. Smart dietary planning, strategic use of fortified foods, and reliable supplementation are necessary to fill these nutritional gaps and support long-term wellness.

Key Points

Vitamin B12 is crucial: As it's not reliably available in unfortified plant foods, regular supplementation or consistent intake of fortified products is essential for vegans.
Vitamin D requires attention: Vegan sources of D3 are limited, so supplementation from lichen or consuming fortified foods is vital, especially during darker months.
Enhance iron absorption: Plant-based non-heme iron is less bioavailable; pairing iron-rich foods with vitamin C significantly boosts absorption.
Source calcium deliberately: Vegans must actively seek out calcium from fortified plant milks and yoghurts, calcium-set tofu, and low-oxalate greens to maintain strong bones.
Supplement for active omega-3s: Since the body inefficiently converts ALA to EPA and DHA, an algae-based oil supplement is the most reliable source for these vital fatty acids.
Mind minor minerals: Iodine and zinc are also potential concerns; sources like iodized salt, seaweed, and sprouted legumes can help, but monitoring may be necessary.

A well-planned vegan diet, rich in fruits, vegetables, and whole grains, can offer significant health benefits, but it requires mindful attention to nutrients that are harder to obtain or absorb from plant sources. For individuals who eliminate all animal-derived foods and by-products, deficiencies in certain vitamins and minerals are a real risk if not proactively addressed. These potential gaps can be mitigated with knowledge and careful meal planning.

Vitamin B12: The Most Critical Concern

Vitamin B12, or cobalamin, is crucial for nerve function, DNA synthesis, and red blood cell formation, and is produced exclusively by microorganisms. Since animals accumulate it in their bodies, meat and dairy are the primary dietary sources for most people. For vegans, unfortified plant foods are not a reliable source. A deficiency can lead to serious neurological issues and megaloblastic anemia.

To ensure sufficient intake, experts advise vegans to:

Supplement regularly: This is considered the most reliable method for maintaining adequate B12 levels. Doses vary, so consulting a healthcare provider is recommended.
Consume fortified foods: Look for breakfast cereals, plant-based milks, and nutritional yeast that have been fortified with B12.

Vitamin D: Sourcing the 'Sunshine Vitamin'

Vitamin D helps regulate calcium and phosphate levels, which is essential for bone health. While the body produces it via sun exposure, dietary sources are important, especially in winter or for those with limited sunlight. The two main dietary forms are D2 (plant-based) and D3 (animal-based). Research indicates D3 is more effective at raising blood levels of the vitamin.

Since vitamin D3 is primarily found in animal products like fatty fish and egg yolks, vegans should consider options such as:

Vegan D3 supplements: These are now available and derived from lichen.
Fortified foods: Many cereals, plant milks, and spreads are fortified with vitamin D.
Sun exposure: Safe sun exposure during summer months can help boost levels, but it's not a year-round solution for everyone.

Iron and Calcium: The Bone and Blood Connection

Iron is vital for red blood cell production and oxygen transport, while calcium is critical for bone and teeth health. A vegan diet can be high in iron, but it contains non-heme iron, which is absorbed less efficiently by the body than the heme iron found in meat. Similarly, avoiding dairy means vegans must be deliberate about their calcium sources.

To improve intake and absorption:

Enhance iron absorption: Pair iron-rich plant foods like lentils, beans, and spinach with vitamin C-rich foods such as citrus fruits, peppers, and broccoli. Avoid drinking tea or coffee with iron-rich meals, as they inhibit absorption.
Choose bioavailable calcium: Look for calcium-set tofu, fortified plant milks and yoghurts, sesame seeds, and low-oxalate greens like kale and bok choy.

Omega-3 Fatty Acids: Brain and Heart Support

Omega-3 fatty acids, particularly EPA and DHA, are crucial for brain and heart function. While vegans can get alpha-linolenic acid (ALA) from flaxseed and walnuts, the body's conversion of ALA to EPA and DHA is inefficient. This can result in lower levels of active omega-3s in vegans compared to omnivores.

Supplement with algal oil: Algae-based oil is a direct vegan source of EPA and DHA, making it an effective way to boost levels.

Other Key Nutrients: Iodine, Zinc, and Selenium

Several other nutrients require attention on a vegan diet. Iodine is necessary for thyroid hormone production, but its levels in plants are unreliable. Zinc is important for immune function and cell growth, but its absorption from plants can be hindered by phytates. Selenium's content in plants varies depending on soil concentration.

Iodine: Use iodized salt or consume fortified plant milks and a variety of seaweed in moderation.
Zinc: Soaking, sprouting, and fermenting legumes and grains can improve zinc bioavailability. Some foods like pumpkin seeds and fortified cereals are good sources.
Selenium: Sources include Brazil nuts, mushrooms, and seeds, though supplementation may be necessary depending on your location's soil content.

Comparison of Common Deficiencies and Solutions


Nutrient	Why Deficiency Occurs	Omnivore Source	Vegan Food Source	Supplementation Needed?
Vitamin B12	Not naturally present in plants; produced by microbes.	Meat, fish, eggs, dairy.	Fortified cereals, nutritional yeast, fortified plant milks.	Yes, strongly recommended.
Vitamin D	D3 type is animal-sourced; limited sun exposure.	Fatty fish, egg yolks, fortified dairy.	Fortified plant milks/cereals, sun exposure, UV-treated mushrooms.	Recommended (especially winter).
Iron	Non-heme form has lower bioavailability.	Red meat, fish.	Lentils, beans, tofu, fortified cereals, leafy greens.	Possibly, with monitoring, especially for women.
Calcium	Lack of dairy products.	Milk, cheese, yoghurt.	Calcium-set tofu, fortified plant milks, leafy greens.	Possibly, if intake is low.
Iodine	Unreliable levels in plant foods.	Dairy, fish, eggs, iodized salt.	Iodized salt, seaweed (moderation), fortified plant milks.	Recommended for many.
Omega-3 (DHA/EPA)	Inefficient conversion from plant-based ALA.	Fatty fish, fish oil.	Algae-based supplements.	Recommended, especially for brain health.

Conclusion

While the nutritional landscape for vegans can present challenges, a well-thought-out approach ensures these deficiencies can be avoided. Combining a diverse diet of whole plant foods with fortified products and targeted supplementation for critical nutrients like Vitamin B12 is the most effective strategy. Regular monitoring of your nutrient status with a healthcare provider is also a prudent measure to ensure long-term health and well-being. A thriving vegan diet is not about elimination, but about conscious, informed replacement. For more in-depth information, you can read more at Medical News Today on vegan deficiencies.

Frequently Asked Questions

The most reliable way for vegans to get enough vitamin B12 is through regular supplementation. You can also consistently include B12-fortified foods in your diet, such as nutritional yeast, fortified plant milks, and cereals.

While fortified foods are helpful, relying solely on them can be risky due to inconsistent consumption and varying bioavailability. Many health organizations recommend direct supplementation, particularly for vitamin B12, to ensure adequate and consistent intake.

The most effective vegan source for boosting vitamin D levels is a supplement containing D3 derived from lichen. Fortified plant milks and exposure to sunlight are also beneficial, but can be less reliable depending on location and season.

Not necessarily, but many vegans have lower iron stores due to the lower bioavailability of non-heme iron from plants. Pairing iron-rich plant foods with vitamin C and monitoring levels with a doctor is recommended. Supplementation may be advised, especially for women of childbearing age.

Vegans can obtain essential omega-3s, EPA and DHA, from algae-based oil supplements. While ALA can be found in flax and walnuts, the body's conversion to EPA and DHA is inefficient, making supplementation a more reliable approach for optimal intake.

Vegans can enhance their calcium absorption by consuming calcium-fortified foods and choosing low-oxalate greens like kale. Ensuring adequate vitamin D intake also helps the body absorb calcium effectively.

Good vegan sources of zinc include fortified cereals, legumes, and pumpkin seeds. For iodine, use iodized salt, consume fortified plant milks, and incorporate seaweed in moderation to avoid excessive intake.