What Do Vegans Become Deficient In? Navigating a Plant-Based Diet

October 28, 2025 •

3 min read

According to a systematic review published by the WHO, vegan diets are typically associated with relatively low intakes of several key nutrients, including vitamins B2, B12, and D. Understanding what do vegans become deficient in? is critical for maintaining optimal health while following a plant-based lifestyle.

Quick Summary

A well-planned vegan diet requires careful consideration to avoid nutritional shortfalls in nutrients like vitamin B12, iron, and calcium. Proper diet planning, including fortified foods and supplements, is essential for mitigating nutritional gaps. Specific strategies exist for ensuring adequate intake of essential vitamins and minerals.

Key Points

Vitamin B12 is Non-Negotiable: As it's not reliably available in unfortified plant foods, vegans must use supplements or fortified foods to prevent serious nerve damage.
Enhance Iron Absorption: The iron in plants is less bioavailable; pairing iron-rich foods with vitamin C dramatically increases its absorption.
Source Calcium Strategically: Look beyond dairy and choose fortified plant milks, calcium-set tofu, and low-oxalate greens like kale for adequate calcium intake.
Supplement EPA and DHA: Since the body's conversion of plant-based ALA to the crucial long-chain omega-3s is inefficient, an algae oil supplement is highly recommended.
Ensure Iodine Intake: Rely on iodized salt or a supplement, as the iodine content of plant foods is inconsistent and seaweed intake can be unpredictable.
Optimize Zinc Absorption: Increase zinc intake from legumes and seeds, and improve absorption by soaking and sprouting beans, which reduces phytate content.

Adopting a vegan diet, which excludes all animal products, can offer numerous health benefits but requires careful planning to ensure nutritional adequacy. Certain vitamins and minerals are more abundant or bioavailable in animal products, posing a potential risk for deficiency if a vegan diet is not well-structured. By understanding these risks, vegans can proactively incorporate fortified foods and supplements to meet their needs and maintain optimal health.

Key Nutrients for Vegan Diets

Vitamin B12

Vitamin B12 is crucial for vegans to monitor as it's not reliably present in plant foods. It's essential for healthy blood and nerve function. Since it's mainly in animal products, vegans need B12 supplements or fortified foods like nutritional yeast or some plant milks. Regular intake is vital.

Iron

Iron is needed for oxygen transport. The non-heme iron in plants is less absorbed than heme iron from meat. Vegans are at risk, especially women and athletes. Good sources include lentils and dark leafy greens. Combining iron-rich foods with Vitamin C boosts absorption.

Calcium

Essential for bone health, calcium intake needs attention without dairy. Plant sources like fortified milks and calcium-set tofu are important.

Vitamin D

Supporting calcium absorption and immunity, Vitamin D can be low in vegan diets due to limited natural sources. Fortified foods, UV-exposed mushrooms, and supplements, particularly vegan D3 from lichen, are key. Supplementation is often recommended, especially seasonally.

Iodine

Crucial for thyroid function, iodine content in plants varies. Vegans may need iodized salt or a supplement, avoiding excessive seaweed.

Zinc

Zinc aids immune function and healing. Plant sources exist, but absorption is affected by phytates. Legumes and seeds are good sources, and soaking/sprouting improves absorption.

Omega-3 Fatty Acids (EPA & DHA)

Essential for brain and heart health, these are less available in plant foods. Algae-based supplements are the best direct vegan source as ALA conversion is inefficient.

Navigating Nutrient Needs: Comparison Table


Nutrient	Animal-Based Source	Plant-Based Source	Absorption Notes for Vegans
Vitamin B12	Meat, dairy, eggs	Supplements, fortified foods	Not naturally present in most plant foods. Supplementation is non-negotiable.
Iron	Red meat (heme iron)	Lentils, beans, tofu, fortified cereals (non-heme iron)	Absorb non-heme iron less efficiently. Boost with Vitamin C; avoid tea/coffee near mealtimes.
Calcium	Dairy products	Fortified plant milks, calcium-set tofu, kale	Absorption can be inhibited by oxalates in some greens (e.g., spinach).
Vitamin D	Oily fish, eggs, fortified milk	Fortified foods, UV-treated mushrooms, sun exposure	Vitamin D2 from plants and vegan D3 from lichen are available through fortified foods or supplements.
Iodine	Dairy, seafood	Iodized salt, seaweed (variable), supplements	Use iodized salt or a supplement. Be careful not to consume excessive amounts from seaweed.
Zinc	Meat, dairy, eggs	Legumes, nuts, seeds, whole grains	Bioavailability is lower due to phytates. Soaking and sprouting improve absorption.
Omega-3s (EPA/DHA)	Oily fish, eggs	ALA in flax/chia/walnuts; EPA/DHA from algae supplements	Conversion from ALA is inefficient. Algae-based EPA/DHA supplements are recommended.

Preventing Deficiencies with Smart Planning

Preventing deficiencies involves a diverse diet of whole foods, incorporating fortified foods, and considering supplements for key nutrients. This proactive approach ensures a healthy vegan diet.

Conclusion

A well-planned vegan diet is key to avoiding nutrient deficiencies. By understanding potential shortfalls in nutrients like B12, iron, calcium, Vitamin D, iodine, zinc, and Omega-3s, vegans can make informed food choices, use fortified products, and take supplements when necessary. This ensures the health benefits of a plant-based diet are fully realized. Resources like Vegan Health provide further guidance.

Vegan Health

Frequently Asked Questions

Vitamin B12 is the most common and serious nutrient deficiency risk for vegans because it is not naturally found in most plant foods. Supplements or fortified foods are essential for all vegans.

Yes, a vegan can get enough iron, but it requires strategic planning. Plant-based iron (non-heme) is less bioavailable. Vegans should consume plenty of iron-rich foods and pair them with vitamin C to boost absorption.

While flaxseeds and walnuts provide ALA Omega-3s, the body’s conversion to the more crucial EPA and DHA is inefficient. The best direct vegan source for EPA and DHA is an algae oil supplement.

Vegans can meet their calcium needs by consuming calcium-fortified plant milks and yogurts, calcium-set tofu, and a variety of green leafy vegetables like kale and collard greens.

Fortified foods can be a significant source of nutrients like B12, Calcium, and Vitamin D. However, they may not be sufficient for all individuals, and supplements are often recommended, especially for Vitamin B12.

Most health experts recommend that vegans take a Vitamin B12 supplement. Supplements for Vitamin D, Omega-3s (EPA/DHA), and Iodine are also often advised, depending on dietary intake and other factors.

Seaweed can contain iodine, but the content varies greatly and can lead to excessive intake, which is also harmful. For a consistent, safe intake, iodized salt or a supplement is a more reliable option.

Legumes (beans, lentils), nuts (cashews), seeds (pumpkin, sesame), and whole grains are good plant-based sources of zinc. Soaking and sprouting can improve zinc absorption.

Many common dietary sources of Vitamin D are animal-based. Vegans, especially those with limited sun exposure, may not get enough and should consider fortified foods or a supplement.

Vegans can improve the absorption of non-heme iron from plant foods by pairing them with sources of Vitamin C, such as citrus fruits, bell peppers, or strawberries.

Vitamin B12 is essential for several critical bodily functions, including the formation of healthy red blood cells, nerve function, and the synthesis of DNA.

While some plant foods contain ALA, which the body can convert to EPA and DHA inefficiently, the most reliable vegan source for direct intake of EPA and DHA is an algae-based oil supplement.