Navigating Vegan Nutrition: What Deficiency is More Common Among Vegans?

October 25, 2025 •

5 min read

Numerous systematic reviews and long-term cohort studies have identified vitamin B12 deficiency as one of the most prevalent issues among those following a vegan diet. Understanding what deficiency is more common among vegans is the first step toward a well-planned and nutritionally adequate plant-based lifestyle.

Quick Summary

This article outlines the nutrients vegans are most commonly at risk of lacking, including vitamin B12, iron, calcium, and omega-3s. It explores the reasons for these potential shortfalls and offers practical strategies for ensuring a balanced and healthy vegan diet.

Key Points

Vitamin B12 is Crucial: As it is found almost exclusively in animal products, vegans must supplement or consume fortified foods to avoid deficiency.
Iron Absorption is Lower: Plant-based iron (non-heme) is less bioavailable, requiring strategic food pairing with vitamin C to enhance absorption.
Calcium Intake Requires Planning: Vegans must prioritize calcium-rich plant foods and fortified products, as dairy is excluded and some plant compounds inhibit absorption.
Omega-3s Need Targeted Intake: Conversion of plant-based ALA to EPA and DHA is inefficient, making algae-based supplements a reliable source for vegans.
Zinc Bioavailability is a Factor: The presence of phytates in plant foods reduces zinc absorption, potentially increasing the zinc needs for vegans.
Supplements are Essential: For several nutrients, especially vitamin B12 and often DHA/EPA and Vitamin D, supplementation is the most reliable way for vegans to ensure adequate intake.
Diversify Your Diet: Eating a wide variety of whole plant foods is key to balancing nutrient intake and overcoming the reduced bioavailability of some minerals.

Before making significant dietary changes or starting any new supplement regimen, especially for those following a vegan diet, it is important to consult with a healthcare provider or a registered dietitian. Information provided here is for general knowledge and should not be considered medical advice.

While a vegan diet offers many health benefits, including lower risks of heart disease, type 2 diabetes, and certain cancers, it also requires careful planning to avoid nutritional shortfalls. A diet that excludes entire food groups like animal products can increase the risk of certain micronutrient deficiencies if not properly managed. Awareness and strategic dietary choices are essential for maintaining optimal health on a vegan diet.

The Most Common Nutritional Deficiency: Vitamin B12

Among the various nutrients to consider, vitamin B12 is unequivocally the most critical for vegans, as it is found naturally almost exclusively in animal products. This essential nutrient is vital for several bodily functions, including red blood cell formation, neurological function, and DNA synthesis. Low B12 intake can lead to serious health issues, including megaloblastic anemia and irreversible neurological damage.

Since no unfortified plant food contains a significant amount of active vitamin B12, supplementation is not just recommended but is essential for vegans. Waiting for deficiency symptoms to appear, which can take years, is a risky approach, and routine monitoring of B12 status is advised.

Vegans can meet their B12 needs by consuming fortified foods or taking a vitamin B12 supplement.

Other Key Nutrients for Vegan Diets

While vitamin B12 is the most prominent concern, several other nutrients require attention and careful planning in a vegan diet.

Iron

Iron is crucial for oxygen transport via hemoglobin and is found in many plant foods like legumes, nuts, and leafy greens. However, the iron in plant foods (non-heme iron) is less bioavailable than the heme iron found in meat. Vegans often have similar or higher iron intake than omnivores but may have lower iron stores (ferritin).

To maximize iron absorption, vegans should:

Combine iron-rich plant foods with sources of vitamin C (e.g., peppers, citrus).
Avoid drinking coffee or tea within an hour of iron-rich meals, as they can inhibit absorption.
Soak and sprout grains and legumes to reduce phytic acid, which can also inhibit iron absorption.

Calcium and Vitamin D

Calcium is essential for maintaining strong bones and teeth, and vegans, who exclude dairy, need to be proactive about their intake. Plant sources of calcium include leafy greens, tofu (calcium-set), and fortified plant milks.

Vitamin D is necessary for calcium absorption. While our bodies produce vitamin D from sunlight, many people, including vegans, may not get enough, especially during winter months. Reliable vegan sources include:

Vitamin D-fortified foods (plant milks, cereals).
UV-treated mushrooms.
Supplements, which are often recommended for optimal intake, particularly during months with less sunlight.

Omega-3 Fatty Acids (EPA and DHA)

The human body can convert the plant-based omega-3 alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are vital for brain and heart health. However, this conversion process is very inefficient. As a result, vegans typically have lower blood concentrations of EPA and DHA than omnivores.

Reliable sources of EPA and DHA for vegans include:

Algae-based supplements.
Foods fortified with DHA from microalgae.

Zinc

Zinc is a trace mineral important for immune function, growth, and wound healing. Although plant-based zinc sources exist (legumes, nuts, seeds), their bioavailability is reduced by phytates. This can lead to lower zinc levels among some vegans, with some studies suggesting an impact on immune response. Regular intake of zinc-rich foods and considering supplementation can help.

Iodine

Iodine is necessary for the production of thyroid hormones. A risk of deficiency exists for vegans, especially if they do not use iodized salt. Sources include iodized salt, seaweed (in moderation), and fortified soy milk.

Comparison of Nutrient Needs: Vegan vs. Omnivore


Nutrient	Vegan Diet Considerations	Omnivore Diet Considerations
Vitamin B12	Must be obtained from supplements or fortified foods, as natural sources are animal-based.	Found in meat, dairy, and eggs; intake is usually sufficient through diet alone.
Iron	High intake is possible, but absorption of non-heme iron is lower. Requires pairing with vitamin C.	Contains highly bioavailable heme iron, making absorption more efficient.
Calcium	Needs focus on fortified plant milks, tofu, and specific vegetables (kale, broccoli) due to dairy exclusion.	Dairy products are a primary, highly absorbable source.
Vitamin D	Sources are limited to sunlight, fortified foods, and supplements; vegan D3 from lichen is available.	Sources include fatty fish, eggs, and fortified foods, in addition to sun exposure.
Omega-3s	Conversion of ALA to EPA/DHA is inefficient; algae-based supplements are the most reliable direct source.	Oily fish is a direct and efficient source of EPA and DHA.
Zinc	Bioavailability is lower due to phytates in plant foods; intake may be lower, sometimes requiring supplementation.	Red meat and shellfish provide readily available zinc.
Iodine	Intake depends on use of iodized salt, fortified foods, or seaweed, as most plant foods are not reliable sources.	Seafood and dairy are significant sources.

Preventing Deficiencies on a Vegan Diet

Effective nutritional planning is key to preventing deficiencies and reaping the full health benefits of a vegan lifestyle. A multifaceted approach that includes whole foods, fortified products, and strategic supplementation is most effective.

Dietary Strategies

Diversify your protein sources by combining legumes, nuts, seeds, and whole grains throughout the day to ensure a full spectrum of amino acids. To boost non-heme iron absorption, regularly pair sources like lentils or spinach with vitamin C-rich foods like citrus fruits or peppers. For calcium intake, incorporate a variety of plant-based sources like calcium-set tofu, kale, and fortified milks.

Fortified Foods

Many staple vegan foods are now fortified with crucial vitamins and minerals. Make a habit of checking labels for fortification when buying plant milks, breakfast cereals, nutritional yeast, and certain juices. These products can significantly contribute to meeting daily requirements for vitamin B12, vitamin D, and calcium.

Supplements

For nutrients that are difficult to get reliably from food alone, supplementation is the most prudent approach. Vitamin B12 supplementation is universally recommended for all vegans. Additionally, an algae-based DHA/EPA supplement can provide a reliable source of these long-chain fatty acids. In regions with limited sun exposure, a vitamin D supplement is also advisable. A zinc supplement may be beneficial for those with lower absorption or inadequate intake.

Conclusion

While a vegan diet offers substantial health and environmental benefits, it requires proactive dietary management to avoid specific nutrient deficiencies. The most common and critical deficiency to guard against is vitamin B12, which mandates reliable supplementation. Other nutrients like iron, calcium, vitamin D, omega-3 fatty acids, and zinc also require careful attention, though they can often be managed with mindful dietary choices and fortified foods. By being informed and strategic with your nutrition plan, a vegan diet can be a sustainable and exceptionally healthy choice for a lifetime.
For more specific guidance on vegan nutrition, consulting with a registered dietitian is highly recommended.

Frequently Asked Questions

The single most important supplement for vegans is vitamin B12. Because it is found almost exclusively in animal products, vegans must rely on supplements or fortified foods to meet their requirements and prevent serious health issues.

Vegans can get enough calcium by consuming calcium-rich plant foods like kale and broccoli, and regularly incorporating calcium-fortified products such as plant milks, tofu, and cereals. It is also important to ensure adequate vitamin D intake for proper calcium absorption.

While vegans often have a high intake of iron from plant-based sources, the iron is less bioavailable (non-heme) compared to animal sources. As a result, vegans may have lower iron stores, and strategic food pairing (like adding vitamin C) is important to maximize absorption.

For optimal health, most health organizations recommend that vegans take a vitamin B12 supplement. Supplements for omega-3 fatty acids (DHA/EPA), vitamin D, and potentially zinc may also be recommended depending on individual circumstances and diet planning.

The body can convert plant-based ALA into EPA and DHA, but the process is inefficient. While consuming ALA-rich foods like flaxseed and walnuts is beneficial, algae-based supplements are the most reliable way for vegans to ensure sufficient levels of EPA and DHA.

Zinc from plant foods is less available for absorption due to phytates. Therefore, vegans might need to consume more zinc to meet their needs or consider a supplement, particularly if they have symptoms of deficiency.

Symptoms of vitamin B12 deficiency can include fatigue, anemia, nerve damage (tingling/numbness), and neurological changes. It is important to note that these symptoms can be gradual and a blood test is the most reliable way to monitor status.

Vegans can ensure they get enough iodine by using iodized salt in cooking and incorporating iodine-rich foods like seaweed (in moderation), cranberries, and fortified foods into their diet.

Children on a vegan diet have the same potential for deficiencies as adults and need especially careful planning to ensure adequate intake of nutrients like B12, Vitamin D, calcium, and iron to support proper growth and development. Working with a healthcare provider is recommended.

Yes. While supplementation is often necessary, it's possible to exceed safe upper limits for some nutrients if not monitored. It is always best to consult a healthcare provider before starting a new supplement regimen, especially for those who are pregnant or have existing health conditions.