Which Nutrient Is a Concern for Vegans? A Comprehensive Guide

December 15, 2025 •

4 min read

According to research, vegans are at a high risk of vitamin B12 deficiency because this crucial vitamin is naturally found almost exclusively in animal products. This makes vitamin B12 the most significant nutrient that is a concern for vegans, though several others also require attention for optimal health.

Quick Summary

Vegans face a significant risk of Vitamin B12 deficiency as it is not naturally present in plant foods. Addressing this requires consuming fortified foods or supplements. Other key nutrients, such as iron, calcium, vitamin D, and omega-3s, also require careful attention.

Key Points

Vitamin B12: This is the most critical nutrient for vegans as it is not reliably found in unfortified plant foods, necessitating fortified foods or supplements.
Iron Absorption: Vegans must be mindful of non-heme iron absorption, pairing iron-rich foods with Vitamin C and avoiding inhibitors like coffee or tea during meals.
Calcium and Vitamin D: Adequate intake requires consistent consumption of fortified plant milks, calcium-set tofu, and leafy greens, supplemented by sunlight exposure or supplements for Vitamin D.
Omega-3s: Since the conversion of plant-based ALA to EPA and DHA can be limited, vegans should incorporate direct sources like algae-based supplements.
Dietary Planning: A well-planned vegan diet is key to avoiding deficiencies; understanding nutrient sources and managing absorption is essential for optimal health.

Vitamin B12: The Primary Vegan Concern

Vitamin B12 is an essential nutrient that plays a vital role in nerve function, DNA synthesis, and the formation of red blood cells. Since it is produced by microorganisms and is not naturally present in plant foods, vegans must obtain it from external sources. The body can store B12 for several years, which is why a deficiency might not manifest immediately after transitioning to a vegan diet. However, without a reliable source, long-term health can be compromised.

Symptoms and Consequences of B12 Deficiency

A deficiency can lead to a range of physical, neurological, and psychological issues that can be subtle at first and worsen over time. Initial symptoms might include fatigue, weakness, lack of energy, and pins and needles. More severe consequences can include nerve damage, memory problems, psychological issues like depression, and potentially irreversible neurological damage, especially in infants of deficient mothers.

How Vegans Can Obtain Vitamin B12

The only reliable sources of B12 for vegans are fortified foods and supplements. The Vegan Society and other health organizations emphasize the importance of one of these methods:

Fortified Foods: Consuming B12-fortified foods multiple times a day is a viable option. Look for products like fortified plant milks, breakfast cereals, and nutritional yeast. Always check labels to confirm the fortification and serving size.
Supplements: For many, supplements are the most convenient and cost-effective method. A daily low-dose supplement or a weekly higher-dose one can be effective. Sublingual (dissolving under the tongue) supplements can enhance absorption.

Other Nutrients Requiring Attention

Beyond B12, several other nutrients are important for a balanced vegan diet. Here's a look at some key ones and how to ensure adequate intake.

Iron

Iron is crucial for red blood cell production, but the non-heme iron found in plant foods is not as easily absorbed as the heme iron in animal products. Vegans often have lower iron stores, but this can be managed effectively with a well-planned diet.

Enhancing Absorption: Pairing iron-rich plant foods with sources of Vitamin C (such as citrus, bell peppers, and broccoli) significantly boosts absorption.
Rich Vegan Sources: Excellent sources include lentils, chickpeas, tofu, tempeh, leafy greens, fortified cereals, and dried fruits.

Calcium

Calcium is vital for bone health, and vegans must rely on non-dairy sources.

Good Sources: Fortified plant milks (soya, oat), calcium-set tofu, certain leafy greens (kale, collards, broccoli), sesame seeds, and tahini are all good options.
Absorption Note: Note that spinach is a poor source due to its high oxalate content, which inhibits calcium absorption.

Vitamin D

Vitamin D is necessary for the body to absorb calcium. While it can be obtained from sunlight, dietary sources are important, especially in less sunny climates.

Vegan Sources: Fortified plant milks, fortified cereals, and mushrooms exposed to UV light are sources. Supplements are also a reliable way to meet requirements, particularly during autumn and winter.

Omega-3 Fatty Acids

Omega-3s are important for brain, nerve, and heart health. While plant foods provide ALA (alpha-linolenic acid), the conversion to the more crucial EPA and DHA can be limited.

ALA Sources: Incorporate foods like flaxseeds, chia seeds, hemp seeds, and walnuts into your daily diet.
EPA and DHA: Consider an algae-based supplement to ensure adequate levels of these crucial omega-3s.

Nutrient Absorption: Vegan vs. Omnivore


Nutrient	Absorption in Vegans	Absorption in Omnivores
Vitamin B12	Requires fortified foods or supplements; not naturally absorbed from plant foods.	Easily absorbed from animal products like meat, fish, and dairy.
Iron	Non-heme iron absorption is enhanced by Vitamin C and can be affected by inhibitors.	Heme iron from animal products is more readily absorbed.
Calcium	Absorption from fortified plant milks and certain greens is efficient, but oxalates in some plants can inhibit absorption.	Readily absorbed from dairy products.
Omega-3s	Primarily ALA, with limited conversion to EPA and DHA; direct supplementation via algae oil is recommended for optimal levels.	Primarily EPA and DHA from fatty fish.

Conclusion

While a vegan diet can offer numerous health benefits, the nutrient that is a concern for vegans above all others is vitamin B12. Its absence in natural plant foods makes supplementation or regular intake of fortified products non-negotiable for long-term health. By also paying careful attention to sources and absorption of iron, calcium, vitamin D, and omega-3s, vegans can ensure a nutritionally complete and healthy diet. Thorough planning is key to addressing these potential nutritional gaps and reaping the full benefits of a plant-based lifestyle.

The Vegan Society offers further guidance on vegan nutrition

Frequently Asked Questions

The most important nutrient for vegans to supplement is Vitamin B12, as it is not reliably available from plant-based foods.

Vitamin B12 is produced by microorganisms, not by plants. It is found in animal products because animals consume these microbes or have them present in their digestive systems.

The initial symptoms of B12 deficiency are often non-specific and can include fatigue, weakness, lack of energy, and a feeling of 'pins and needles'.

To improve iron absorption, vegans should combine iron-rich foods (like lentils and leafy greens) with Vitamin C-rich foods (such as bell peppers or citrus) and avoid consuming coffee or tea during meals.

The best vegan calcium sources include fortified plant milks and juices, calcium-set tofu, collard greens, kale, and tahini.

While plant foods contain ALA, which converts to EPA and DHA, conversion can be inefficient. An algae-based supplement is recommended to ensure optimal intake of EPA and DHA.

No, a vegan cannot reliably get all necessary nutrients from food alone. Vitamin B12 is the key nutrient that must be obtained from supplements or fortified foods.