Understanding What Are Vegans Likely to Be Deficient In?

October 28, 2025 •

4 min read

According to a systematic review published by the WHO, vegan diets are commonly associated with lower intakes of vitamins B2, B12, D, iodine, zinc, calcium, and selenium. While a well-planned vegan diet can be very healthy, it's crucial for followers to understand what are vegans likely to be deficient in and how to address these potential nutritional gaps.

Quick Summary

A strict vegan diet may lead to lower intake and reduced bioavailability of specific vitamins and minerals, including B12, vitamin D, calcium, iron, zinc, iodine, and omega-3s. Careful dietary planning, the use of fortified foods, and strategic supplementation are necessary to ensure nutritional adequacy and long-term health. Mitigation strategies like combining certain nutrients and proper food preparation can significantly improve absorption.

Key Points

Vitamin B12 is essential for all vegans: As it is not naturally found in plants, supplementation or regular intake of fortified foods is non-negotiable for nerve health.
Monitor Vitamin D levels: Relying solely on the sun is insufficient for most people; fortified foods and supplements are often required, especially in winter.
Plan for adequate calcium intake: Since dairy is excluded, vegans should prioritize fortified plant milks and calcium-set tofu, along with low-oxalate leafy greens like kale.
Enhance iron absorption: Pairing plant-based iron sources like legumes with vitamin C-rich foods is vital to maximize uptake and prevent deficiency.
Address zinc bioavailability concerns: Soaking and sprouting legumes can improve absorption, and some individuals may benefit from supplementation to meet their needs.
Incorporate iodine sources: Regular consumption of iodized salt, seaweed (in moderation), or fortified plant milk is important for thyroid function.
Ensure enough EPA and DHA: While plant foods contain ALA, conversion to EPA/DHA is poor; an algae-based supplement is the most reliable way for vegans to get these vital omega-3 fatty acids.
Consult a healthcare professional: Regular monitoring of nutrient levels via blood tests is recommended for vegans to ensure a balanced and healthy diet.

The Critical Nutrient: Vitamin B12

Vitamin B12 is arguably the most critical nutrient for vegans to monitor, as it is not found naturally in any plant-based foods. This essential vitamin is crucial for maintaining a healthy nervous system and forming red blood cells. A deficiency can lead to serious and irreversible neurological damage, anemia, and fatigue.

Sources: The only reliable vegan sources of B12 are fortified foods and supplements.
Fortified foods: Look for breakfast cereals, plant-based milks, and nutritional yeast fortified with B12.
Supplementation: Taking a daily B12 supplement is highly recommended for all vegans to ensure adequate intake.

Vitamin D: The Sunshine Vitamin

While our bodies can produce vitamin D from sun exposure, many people—vegans and omnivores alike—do not get enough, especially during winter months or with limited outdoor time. Vitamin D is vital for calcium absorption and bone health.

Sources: Reliable vegan sources are limited and include fortified plant milks and cereals, as well as UV-exposed mushrooms.
Supplementation: A supplement is often necessary, especially from autumn to spring, as food sources and sun exposure may not suffice.

Calcium for Strong Bones

Calcium is essential for bone and tooth health. While dairy products are a common source, vegans must be deliberate about their intake through alternative sources. Some plant-based calcium sources are less bioavailable due to compounds like oxalates.

Optimal Sources: Focus on low-oxalate, calcium-rich greens like kale, broccoli, and collard greens.
Fortified Products: Use calcium-fortified plant milks, juices, and tofu set with a calcium salt.

Iron: The Importance of Pairing

Vegans often have lower iron stores than omnivores because the non-heme iron found in plants is less efficiently absorbed than the heme iron from meat. However, vegans can have higher iron intakes overall from sources like legumes, whole grains, nuts, and leafy greens.

Enhancing Absorption: Pair iron-rich plant foods with foods high in vitamin C (like citrus, bell peppers, and strawberries) to significantly boost absorption.
Inhibitors: Avoid consuming tea or coffee with iron-rich meals, as tannins can hinder absorption.

Zinc for Immunity and Metabolism

Zinc is needed for immune function, wound healing, and metabolic processes. Phytates in plant foods like legumes and whole grains can bind to zinc and reduce its absorption.

Maximizing Absorption: Soaking, sprouting, and fermenting legumes and grains can help to increase zinc availability.
Sources: Excellent vegan sources include lentils, chickpeas, tofu, tempeh, nuts, seeds, and fortified cereals.
Supplementation: Some studies suggest that vegans may need up to 50% more zinc than omnivores to compensate for reduced absorption, making supplementation a wise choice for some.

Iodine and Thyroid Health

Iodine is a trace element vital for producing thyroid hormones that regulate metabolism. The iodine content of plants can vary depending on the soil where they were grown.

Sources: Reliable vegan sources include iodized salt, seaweed (use in moderation due to potential for excessive intake), and fortified plant-based milks.

Omega-3 Fatty Acids: ALA, EPA, and DHA

Vegans can easily get the short-chain omega-3 fatty acid, Alpha-linolenic acid (ALA), from sources like flaxseeds, chia seeds, and walnuts. However, the conversion of ALA into the more beneficial long-chain EPA and DHA is inefficient in the body.

ALA Sources: Good sources include flaxseed oil, chia seeds, and walnuts.
EPA/DHA Sources: To ensure adequate levels, many health professionals recommend an algae-based DHA/EPA supplement.

Comparison of Key Nutrients: Vegan vs. Omnivore Diet


Nutrient	Primary Source (Omnivore)	Vegan Source & Challenge	Strategy for Vegans
Vitamin B12	Meat, dairy, eggs	Not naturally present in plants	Supplementation or fortified foods
Vitamin D	Sunlight, fortified milk, fatty fish	Sun, fortified plant milk/cereals, UV mushrooms	Regular sun exposure & supplementation
Calcium	Dairy products	Fortified milks, tofu, kale	Fortified foods; choose low-oxalate greens
Iron	Red meat (heme iron)	Legumes, greens (non-heme iron, lower absorption)	Pair with vitamin C; soak/sprout legumes
Zinc	Meat, shellfish	Legumes, nuts (absorption inhibited by phytates)	Soak/sprout foods, consider supplementation
Iodine	Dairy, fish, iodized salt	Iodized salt, seaweed, fortified milks	Use iodized salt in cooking
Omega-3s (EPA/DHA)	Fatty fish	Inefficient conversion from plant-based ALA	Algae-based supplements

Conclusion

While a vegan diet offers numerous health benefits, careful planning is essential to avoid potential nutritional deficiencies. A comprehensive approach that includes a varied diet of whole plant foods, consistent use of fortified products, and strategic supplementation for key nutrients like B12, vitamin D, and omega-3s is the best way forward. Individuals should consult with a healthcare provider or a registered dietitian to create a personalized plan and consider regular blood tests to monitor their nutrient status. Education and awareness are the most powerful tools for maintaining long-term health on a plant-based diet.

For more in-depth nutritional guidance, resources like VeganHealth.org provide valuable, evidence-based information to help you optimize your plant-based diet.

Tips for Optimizing Nutrient Absorption

Utilize Food Preparation: Soaking nuts, seeds, and legumes reduces phytates, improving zinc and iron absorption.
Pair Smartly: Always combine plant-based iron sources with vitamin C-rich foods to boost iron uptake.
Diversify Your Diet: Eating a wide variety of whole plant foods ensures a broader spectrum of nutrients and beneficial compounds.
Choose Fortified: Regularly consume fortified plant milks, cereals, and other products to easily meet needs for B12, D, and calcium.

Frequently Asked Questions

Yes, vitamin B12 supplementation is essential for all vegans because B12 is not naturally found in plant-based foods. Relying solely on fortified foods may not be enough to prevent a deficiency, which can cause serious health issues.

Vegans can get calcium from fortified plant milks and tofu set with calcium sulfate. Other good sources include low-oxalate leafy greens like kale and broccoli, as well as sesame seeds and pulses.

To maximize absorption of non-heme iron from plant foods, vegans should pair iron-rich foods (like lentils, spinach, and beans) with a source of vitamin C (such as oranges, bell peppers, or strawberries). Avoid drinking coffee or tea around the time of an iron-rich meal.

While protein intake on a vegan diet can be lower than an omnivorous one, it is generally sufficient if a varied diet is consumed. Vegans should incorporate a variety of protein-rich plant foods like legumes, tofu, tempeh, nuts, and seeds throughout the day.

Vegans can get ALA from walnuts, chia seeds, and flaxseeds. However, for the crucial EPA and DHA, an algae-based supplement is the most direct and efficient source due to the body's low conversion rate of ALA.

Excellent vegan sources of zinc include legumes (beans, lentils), nuts (cashews, almonds), seeds (pumpkin, sesame), and whole grains. Soaking and sprouting can help improve the body's ability to absorb it.

Besides B12, supplements for vitamin D and omega-3s (EPA/DHA) are often recommended. Iodine can be obtained through iodized salt and seaweed, but a supplement may be needed if these aren't consumed regularly. Consulting a doctor is wise to assess individual needs.