What Are Vegans Most Likely to Be Deficient In?

October 8, 2025 •

4 min read

According to a systematic review, vitamin B12 intake among vegans is significantly lower than recommended levels. This highlights why many wonder what vegans are most likely to be deficient in, a critical question for maintaining health on a plant-based diet. A balanced, well-planned approach is essential to avoid common nutritional gaps.

Quick Summary

This guide covers key nutrients often lacking in a poorly planned vegan diet, including vitamin B12, iron, calcium, and vitamin D. It offers actionable strategies for incorporating fortified foods and supplements to ensure adequate intake for optimal health.

Key Points

Vitamin B12 is critical for all vegans: B12 is not reliably available from plant sources, so fortification or supplementation is essential to prevent neurological damage and anemia.
Enhance iron absorption effectively: Pair plant-based iron sources like legumes and greens with vitamin C-rich foods and avoid tea or coffee during meals.
Focus on diversified calcium sources: Utilize fortified plant milks, calcium-set tofu, and low-oxalate greens like kale to meet calcium needs and support bone health.
Ensure adequate vitamin D intake: Relying solely on the sun is insufficient for many; use fortified foods, UV-exposed mushrooms, or consider taking a vegan D3 supplement, especially during darker seasons.
Don't forget iodine and Omega-3s: Use iodized salt or consider supplements for iodine, and think about an algae-based EPA/DHA supplement for optimal omega-3 levels, as plant sources of ALA have poor conversion.
A well-planned vegan diet is complete: With awareness and strategic planning, including targeted supplementation and fortified foods, a vegan diet can be nutritionally sufficient.

Disclaimer

This article provides general information and is not a substitute for professional medical advice. Always consult a healthcare provider or a registered dietitian before making significant changes to your diet or supplementation regimen.

Understanding the Vegan Diet and Potential Nutritional Gaps

A vegan diet, which excludes all animal products, including meat, dairy, eggs, and honey, can offer numerous health benefits, such as a lower risk of certain chronic diseases. However, eliminating entire food groups requires careful planning to ensure nutritional adequacy. Some nutrients are naturally scarce in plant-based sources, necessitating a thoughtful approach to food choices, fortification, and supplementation. Addressing these potential deficiencies is crucial for maintaining long-term health and well-being.

Key Deficiencies in a Vegan Diet

Vitamin B12

Vitamin B12 is arguably the most critical nutrient for vegans to monitor, as it is found naturally only in animal products. This vitamin is essential for nerve function, red blood cell formation, and DNA synthesis. Deficiency can lead to serious neurological damage and anemia.

Reliable Vegan Sources of B12:

Fortified Foods: Many plant milks, breakfast cereals, and soy products are fortified with B12. It is essential to check labels carefully to ensure adequate intake.
Nutritional Yeast: This yeast is often fortified with B12 and can be used to add a cheesy flavour to dishes.
Supplements: Regular B12 supplementation is important for vegans.

Iron

While many plant foods contain iron, the non-heme iron found in plants is not as readily absorbed by the body as the heme iron from animal sources. However, vegans do not have a higher rate of iron deficiency anemia than omnivores if their diet is well-planned.

Enhancing Iron Absorption:

Pair with Vitamin C: Consuming vitamin C-rich foods (like citrus fruits, bell peppers, or strawberries) with iron sources significantly boosts absorption.
Avoid Inhibitors: Tannins in tea and coffee can inhibit absorption, so it's best to avoid these beverages with meals.
Best Vegan Sources: Legumes (lentils, beans, chickpeas), dark leafy greens (kale, spinach), nuts, seeds, and fortified cereals are excellent sources.

Calcium

Calcium is vital for bone health, muscle contractions, and nerve function. Vegans may have lower calcium intake than non-vegans, and some studies suggest lower bone mineral density.

Key Vegan Calcium Sources:

Fortified Plant Milks and Yogurts: These are a major source of calcium for vegans.
Green Leafy Vegetables: Good sources include kale, bok choy, and collard greens (note that spinach contains oxalates which inhibit calcium absorption).
Calcium-Set Tofu: Tofu set with calcium sulfate is a rich source.
Nuts and Seeds: Sesame seeds, chia seeds, and almonds provide calcium.

Vitamin D

Vitamin D helps the body absorb calcium and supports immune function. Sunlight is the primary source, but dietary intake is also important, especially during darker months. The best food sources are mostly animal-based, putting vegans at higher risk of deficiency.

Vegan Vitamin D Options:

Sun Exposure: Moderate sun exposure can help the body produce vitamin D.
Fortified Foods: Many plant milks and cereals are fortified with vitamin D.
UV-Grown Mushrooms: These can provide a significant amount of the vitamin.
Supplements: A vegan D3 supplement (often from lichen) can contribute to consistent intake.

Iodine

Iodine is necessary for thyroid function. In a Western diet, dairy products are a significant source. Vegans who do not use iodized salt may be at risk of deficiency.

Vegan Iodine Sources:

Iodized Salt: The simplest way to ensure adequate intake is to use iodized salt.
Seaweed: Nori, kelp, and other seaweeds are potent sources, though amounts can vary widely.
Supplements: An iodine supplement can be a consistent way to meet requirements.

Omega-3 Fatty Acids

Omega-3s, particularly EPA and DHA, are important for heart and brain health. The primary source of EPA and DHA is oily fish. While plants provide ALA (alpha-linolenic acid), the body's conversion of ALA to EPA and DHA is inefficient.

Vegan Omega-3 Sources:

ALA-rich Foods: Good sources include chia seeds, flaxseeds, walnuts, and hemp seeds.
Algae-based Supplements: Algae oil is a direct vegan source of EPA and DHA, offering a reliable way to boost levels.

Addressing Nutrient Gaps: A Comparison of Strategies


Nutrient	Food Sources (Vegan)	Absorption Tips	Supplementation (If Needed)	Risks Without Action
Vitamin B12	Fortified plant milks, cereals, nutritional yeast	N/A	Important, as B12 is not reliably available from unfortified vegan sources.	Anemia, irreversible neurological damage.
Iron	Legumes, dark leafy greens, nuts, seeds, fortified cereals	Pair with Vitamin C; avoid tea/coffee with meals.	Not typically needed if diet is varied and planned well.	Fatigue, weakness, anemia.
Calcium	Fortified plant milks, calcium-set tofu, leafy greens (kale, bok choy), sesame seeds	Ensure adequate Vitamin D intake; be mindful of oxalates.	Possibly needed if intake from fortified foods and greens is low.	Lower bone mineral density, osteoporosis.
Vitamin D	Sunlight, UV-exposed mushrooms, fortified foods	Consume with fats (e.g., avocados, nuts).	Can be helpful during autumn/winter or if sun exposure is limited.	Rickets (in children), osteomalacia, weakened immunity.
Iodine	Iodized salt, seaweed	N/A	Can be considered if not regularly using iodized salt.	Thyroid issues, fatigue.
Omega-3s	Chia seeds, flaxseeds, walnuts, hemp seeds, seaweed	N/A	Algae-based EPA/DHA supplements can be helpful to support optimal levels.	Cardiovascular and brain health issues.

Conclusion: Mindful Planning Is Key

Adopting a vegan diet requires mindfulness and a proactive approach to nutrition. While it is true that what vegans are most likely to be deficient in includes vitamin B12, iron, calcium, and vitamin D, these risks are easily managed with proper education and planning. The key is to consume a wide variety of nutrient-dense whole foods, incorporate fortified products, and utilize supplements for nutrients that are either absent or have low bioavailability in a plant-based form. With careful attention, a vegan diet can be a nourishing and complete option for a healthy lifestyle. For further detailed guidance, the Vegan.com Nutrition Guide is an authoritative resource.

Frequently Asked Questions

Yes, vitamin B12 is found naturally almost exclusively in animal products. The only reliable vegan sources are B12-fortified foods and supplements. While some fortified cereals or plant milks can help, supplementation is an important way to avoid deficiency.

Not necessarily. While non-heme iron from plants is less bioavailable, studies show that vegans with well-planned diets do not experience higher rates of iron deficiency anemia than meat-eaters. Pairing iron-rich plant foods with Vitamin C dramatically increases absorption.

Vegans can get enough calcium from fortified plant milks and yogurts, calcium-set tofu, and certain green leafy vegetables like kale and bok choy. Nuts, seeds, and fortified cereals also contribute to overall intake.

Yes. Since animal products are a major source of Vitamin D, vegans should pay attention to their intake. Rely on fortified foods, sun exposure, and potentially a vegan D3 supplement, especially during winter months.

While plant foods like flaxseeds, chia seeds, and walnuts provide ALA omega-3s, the body's conversion to EPA and DHA is inefficient. Vegans should consider an algae-based supplement to support optimal intake of EPA and DHA.

An iodine supplement may be helpful for vegans who do not use iodized salt or consume seaweed regularly. Iodine is vital for thyroid hormone production.

A poorly planned vegan diet that lacks key nutrients like B12 and Vitamin D could impact a child's growth. However, a well-planned vegan diet, with appropriate supplementation and fortified foods, is nutritionally adequate for children and teenagers.