What nutrients are lacking in a vegan diet? An essential guide

According to a 2025 review in the journal Nutrients, poorly planned vegan diets can be lacking in essential nutrients such as vitamin B12, iron, calcium, and zinc. This guide addresses what nutrients are lacking in a vegan diet and provides science-backed strategies for obtaining them through fortified foods, whole plant sources, and supplements.

Quick Summary

This article details key nutrients commonly low in plant-based diets, including vitamin B12, iron, calcium, and zinc. It explores why these deficiencies occur and provides comprehensive strategies for vegans to meet their nutritional needs through diet and supplementation.

Key Points

• Vitamin B12 Requires Supplementation: B12 is not reliably found in plant foods; therefore, regular supplementation via fortified foods or a dedicated B12 supplement is critical for all vegans.

• Enhance Iron Absorption: The iron in plants (non-heme) is less bioavailable. Consuming iron-rich foods like lentils with Vitamin C sources can dramatically increase absorption.

• Consider Algae-based Omega-3s: To obtain the active forms of omega-3s (EPA and DHA), an algae-based supplement is the most efficient and reliable method, as conversion from ALA in seeds and nuts is poor.

• Prioritize Fortified and Plant Calcium: For strong bones, rely on calcium-fortified plant milks and yogurt, as well as calcium-rich leafy greens and tofu.

• Optimize Zinc Bioavailability: To improve zinc absorption from nuts, seeds, and legumes, use food preparation methods like soaking, sprouting, and fermentation.

• Focus on Variety: Eating a wide assortment of legumes, nuts, seeds, grains, fruits, and vegetables is key to covering all nutrient bases on a vegan diet.

• Plan for Nutrients: Proactive and intentional meal planning is essential for vegans to prevent potential nutrient deficiencies and ensure a well-balanced diet.

Essential Nutrients Often Lacking in a Vegan Diet

A well-planned vegan diet is perfectly capable of supporting a healthy lifestyle, but removing all animal products requires careful attention to a few key nutrients that are less abundant or bioavailable in plants. Understanding these potential gaps is the first step toward a balanced and sustainable plant-based eating plan.

Vitamin B12

Vitamin B12 is arguably the most critical nutrient for vegans to monitor, as it is found naturally only in animal products. It is produced by microorganisms and is essential for nerve function and red blood cell formation. A deficiency can lead to severe and irreversible neurological damage.

• Fortified Foods: Many plant-based products are fortified with B12, including nutritional yeast, plant-based milks, and breakfast cereals. Checking nutrition labels is vital to ensure regular intake.
• Supplements: The Vegan Society recommends that all vegans regularly take a B12 supplement to ensure adequate intake. Supplementation is the most reliable method for maintaining optimal B12 levels.

Iron

While many plant foods contain iron, it is in a form called non-heme iron, which is not as readily absorbed by the body as heme iron from meat. Vegans, particularly women, may need to pay special attention to their iron intake.

• Excellent Vegan Sources: Rich sources include lentils, chickpeas, beans, tofu, cashews, and spinach.
• Enhance Absorption: Vitamin C significantly enhances non-heme iron absorption. Pairing iron-rich plant foods with a source of vitamin C—like bell peppers, citrus fruits, or broccoli—can increase bioavailability.

Omega-3 Fatty Acids

Omega-3s are polyunsaturated fats crucial for brain health and reducing inflammation. While vegan diets contain alpha-linolenic acid (ALA), the conversion to the more active forms, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is often inefficient.

• ALA Sources: Abundant plant sources include flaxseeds, chia seeds, walnuts, and hemp seeds.
• DHA/EPA Supplementation: The most direct and reliable way for vegans to obtain EPA and DHA is through an algae-based supplement. Fish get their omega-3s from marine algae, so this cuts out the middle-animal.

Calcium

Calcium is essential for bone health and proper muscle function. Dairy products are a common source, so vegans must ensure they consume enough from plant-based foods.

• Fortified Plant Milks: Fortified almond, soy, and oat milks are excellent sources.
• Other Plant Sources: Tofu (if set with a calcium salt), leafy greens like kale and bok choy, and calcium-set tempeh can contribute significantly to calcium needs.

Zinc

Zinc is an essential mineral for immune function, wound healing, and cell growth. Absorption from plant sources can be hindered by phytates, compounds found in many plant foods.

• Good Vegan Sources: Legumes, nuts, seeds, whole grains, and tofu are all sources of zinc.
• Absorption Strategies: Soaking legumes and sprouting or fermenting foods like tempeh can help reduce phytate levels and increase zinc bioavailability.

Nutrient Comparison Table: Vegan Sources vs. Common Animal Sources

Nutrient	Common Animal Source	Excellent Vegan Sources	Absorption Considerations for Vegans
Vitamin B12	Meat, eggs, dairy	Fortified nutritional yeast, plant milks, and cereals; B12 supplements	Relies entirely on fortified foods or supplementation. Crucial for all vegans.
Iron	Red meat, poultry	Lentils, chickpeas, beans, spinach, tofu	Non-heme iron absorption is enhanced by Vitamin C but inhibited by phytates and tannins.
Omega-3s (EPA/DHA)	Fatty fish, fish oil	Algae-based supplements	ALA from seeds/nuts has very low conversion efficiency. Supplementation is recommended.
Calcium	Dairy products	Fortified plant milks, tofu (calcium-set), kale, bok choy	Absorption can be affected by oxalates in some greens, but is well-absorbed from fortified sources.
Zinc	Oysters, red meat	Legumes, nuts, seeds, whole grains	Absorption is inhibited by phytates. Soaking, sprouting, and fermenting can help increase bioavailability.

Meeting Your Needs on a Vegan Diet

Ensuring all nutritional bases are covered is a straightforward process for vegans who plan their meals thoughtfully. Integrating variety and key strategies can prevent deficiencies and support long-term health. The first step for any new vegan or someone concerned about their nutrient levels is to consult a healthcare provider or a registered dietitian who specializes in plant-based nutrition.

Strategic Meal Planning

To maximize nutrient absorption and meet daily requirements, consider these practical tips:

• Pairing for Absorption: As mentioned, always combine iron-rich foods with vitamin C sources. A lentil soup with bell peppers or a spinach salad with citrus dressing is a simple, effective combination.
• Daily Fortified Foods: Make it a habit to use fortified plant milk in your coffee, smoothies, or cereal. Using nutritional yeast to season meals is also an easy way to boost B12 intake.
• Varied Whole Foods: Incorporate a wide range of whole plant foods. A daily mix of legumes, grains, nuts, seeds, fruits, and vegetables ensures a broad spectrum of vitamins and minerals. Relying on a single type of food, even a healthy one, can lead to imbalances.

The Role of Supplements

While a whole-foods diet should be the foundation, certain supplements are often necessary to prevent deficiencies for anyone on a strict vegan diet. These include:

• Vitamin B12: A supplement is non-negotiable for vegans. The Vegan Society recommends either a daily low-dose or weekly high-dose option.
• Vitamin D: While sunlight is a primary source, many people, especially in less sunny climates, benefit from a supplement. Many plant-based milks and cereals are also fortified.
• Omega-3s: An algae-based DHA/EPA supplement ensures you get the long-chain fatty acids vital for brain and heart health.
• Iodine: Iodine is often lacking and important for thyroid function. An iodized salt, seaweed, or a supplement can help meet needs.

Practical Kitchen Tips

Making small changes to your food preparation can have a big impact on nutrient absorption:

• Soaking and Sprouting: This ancient technique, used for grains and legumes, reduces levels of anti-nutrients like phytates, improving the absorption of minerals like zinc and iron.
• Cooking with Cast Iron: Cooking acidic foods like tomatoes in a cast-iron pan can slightly increase the iron content of your meal.
• Diversify Protein Sources: Mix and match protein sources throughout the day. Combining grains like rice with legumes like beans creates a complete protein profile with a full range of essential amino acids.

Conclusion

While a vegan diet can be one of the healthiest dietary patterns, it is not inherently perfect and requires careful attention to ensure all nutrient needs are met. By understanding which nutrients are potentially lacking in a vegan diet—primarily vitamin B12, bioavailable iron, specific omega-3s, calcium, and zinc—and strategically incorporating fortified foods, whole-plant sources, and supplements, vegans can thrive. A proactive and well-informed approach is the key to enjoying the health benefits of a plant-based lifestyle without compromise.

Get expert advice on vegan nutrition

For personalized advice on maintaining optimal health on a plant-based diet, consider speaking with a registered dietitian who can assess your individual needs and create a tailored nutrition plan. An expert can provide peace of mind and help you navigate the nuances of vegan eating with confidence.

Summary of Key Takeaways

To recap the crucial information discussed, a well-rounded vegan diet is achievable with the right knowledge and planning. Paying close attention to the nutrients outlined in this guide is essential for long-term health.

• Vitamin B12 is essential and requires supplementation. It is not reliably available from plant-based foods.
• Iron absorption can be enhanced. Pair iron-rich legumes and greens with Vitamin C sources like citrus and peppers to boost absorption.
• Omega-3s are best sourced from algae supplements. Relying on ALA conversion is inefficient; use an algae-based supplement for adequate DHA and EPA.
• Calcium comes from fortified foods and leafy greens. Fortified plant milks and certain vegetables like kale are reliable sources.
• Zinc can be optimized with food prep. Soaking or sprouting grains and legumes helps reduce phytates that inhibit absorption.

By following these evidence-based strategies, vegans can enjoy a nutritionally sound and vibrant plant-based lifestyle.

Frequently Asked Questions

What is the single most important nutrient for a vegan to supplement?

The most important nutrient for vegans to supplement is Vitamin B12, as it is not found in sufficient amounts in any natural plant-based foods and a deficiency can cause serious, irreversible neurological damage.

How can vegans increase their iron absorption from plant foods?

Vegans can increase non-heme iron absorption by pairing iron-rich foods like lentils or spinach with a source of Vitamin C, such as bell peppers, citrus fruits, or tomatoes.

Do vegans need to take an omega-3 supplement?

While vegans get ALA omega-3s from foods like flaxseeds, the conversion to active forms (EPA and DHA) is inefficient. Therefore, it is recommended to take an algae-based DHA and EPA supplement for optimal brain and heart health.

What are the best vegan sources of calcium?

Excellent vegan sources of calcium include fortified plant milks and juices, calcium-set tofu, and specific leafy greens like kale and bok choy.

How can vegans get enough zinc if phytates inhibit absorption?

To improve zinc absorption, vegans can soak, sprout, or ferment grains and legumes, as these processes help reduce the phytate content. Consuming a varied diet with good zinc sources like beans, nuts, and seeds is also important.

Can a vegan diet provide enough iodine?

Vegan diets can be low in iodine. To meet requirements, it is recommended to use iodized salt, consume seaweed, or take a supplement, as iodine is essential for thyroid function.

What is the best way for a new vegan to manage their nutrient intake?

New vegans should focus on eating a wide variety of whole plant foods, consistently using fortified products, and regularly taking a B12 supplement. Consulting a registered dietitian specializing in plant-based diets is also highly recommended.