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Knowledge Blog > Nutrition

Nutritional deficiencies in vegans: Recognizing and safely preventing them

The article explains clearly and practically which nutrients require special attention, how to recognize potential deficiencies, and how to reliably avoid them through diet, diagnostics, and targeted supplementation.¹,³

Definition: What exactly is willpower?
Where there's a will, there's a way: Why willpower is important for achieving your goals
How are willpower and motivation related?
Why New Year's resolutions so often fail
The biology behind your drive
What impairs willpower?
Stress blocks self-control: Why stress acts like poison
Body, mind & systems: How to strengthen your willpower
Nutrients as silent partners in the background
Perseverance beats willpower: Systems as the foundation for discipline
Systems that help you persevere: 7 tips for greater willpower
The real prize: A body that keeps pace.
Sources & Bibliography

Is a vegan diet healthy?
Common Nutrient Deficiencies in a Vegan Diet
Vitamin B12 – The Most Well-Known Deficiency in a Vegan Diet
The Role of Vitamin D – Not Only Relevant for Vegans
Omega-3 Fatty Acids – EPA/DHA Deficiency
Iron – Heme Iron vs. Non-Heme Iron
Selenium: Why many buy this micronutrient
Iodine (Iodine) Effect - Essential for the Thyroid Gland
Calcium & Bones in a Vegan Diet
How do I get enough protein as a vegan?
What other deficiencies arise from a vegan diet?
Prevention - how to avoid vegan deficiencies
Which supplements are useful?
Conclusion
Sources & Bibliography

Vegan nutrition: Healthy and possible if well planned.

A purely plant-based diet offers many advantages: abundant fiber, phytochemicals, a favorable fatty acid profile, and a high density of micronutrients in many unprocessed foods. Positions from major professional societies consider well-planned vegetarian and vegan diets suitable for all stages of life, provided critical nutrients are covered in a structured manner.³ A well-planned vegan diet is classified by nutrition societies as healthy and nutritionally appropriate. Different diets, such as vegan, vegetarian, or omnivorous, each have specific nutrient requirements, which is why a conscious and well-planned diet is crucial for preventing deficiencies in vegans and other dietary groups. This addition is crucial: planning . Not because veganism per se causes deficiencies, but because the source, bioavailability, and metabolism of individual nutrients differ between plant-based and omnivorous diets.¹,⁵

In practical terms, this means that vegans should actively monitor their intake of vitamin B12 , vitamin D, omega-3 fatty acids (EPA/DHA), iron, selenium, iodine, calcium, as well as protein and essential amino acids . This can be achieved safely, practically, and sustainably in the long term with the three-pronged approach of nutrition, diagnostics, and targeted supplementation.¹ ,⁵

Nutritional deficiencies in vegans – why certain nutrients need special attention

To remain objective, it helps to distinguish between two levels:

Potential undersupply: Intake remains at the lower limit for weeks to months; laboratory values may still be within the reference range, but show trends.
Clinically relevant deficiency: There are significant laboratory abnormalities and/or symptoms (e.g., megaloblastic anemia in vitamin B12 deficiency, pronounced hypovitaminosis D, overt iron deficiency anemia).1,⁴

Nutrient deficiencies can occur if a vegan diet is not adequately planned, as any diet carries risks of nutrient deficiencies if it is not properly planned.

It is important to distinguish between the two: Veganism does not automatically cause deficiencies – a lack of planning does. Typical mistakes include: not having a reliable vitamin B12 regimen; thinking of omega-3 solely as ALA (flaxseed, chia, walnuts) without including EPA / DHA from algae; uncritically avoiding iodized salt; failing to consider iron bioavailability ; or underestimating the significant regional variations in selenium levels in plant-based foods.¹,³,⁷

This is relevant for doctors and therapists because nonspecific symptoms (fatigue, decreased concentration, reduced performance, skin/hair changes) are often partly related to nutrition and can be avoided with structured prevention and targeted nutrient supply.⁴,⁶

Common nutrient deficiencies in a vegan diet

There are many situations where willpower is important. Perhaps you're familiar with this situation: During your reflection at the turn of the year, you resolve to do more exercise, eat a more balanced diet, or put your phone away in time in the evening to get more sleep.

The top 5 New Year's resolutions¹

Number 5: Having more time for yourself
4th place: Eat a more balanced diet
Third place: More exercise to improve performance
Second place: More time for friends and family
Number 1: Reduce stress

Often, just a small impulse is enough to spark the desire for change. But then comes the frustrating reality : After things went well in the first few days, old patterns quickly creep back in and get in your way.

Does this happen to you too? You're not alone: Various studies show that New Year's resolutions are often forgotten by the next year. A recent survey found that 16% of people with good intentions give up within the first few weeks of January.¹

To avoid exactly that, willpower is important: it ensures that a resolution becomes a lived change . For example, it helps you stick to your training plan even when the sofa is tempting. However, willpower alone is not enough.

But willpower is not a permanent state. It can help overcome obstacles in the short term – but it is not designed to fight against exhaustion, stress, or unfavorable conditions for months on end.

Vitamin B12 – the most common deficiency in vegan diets

Vitamin B12 (Cobalamin) is essential for numerous bodily functions and tasks, including DNA synthesis, blood formation, fatty acid breakdown, and nervous system health. It belongs to the group of cobalamins, with various coenzymes such as methylcobalamin and adenosylcobalamin (Rima) playing a central role in enzymatic reactions. Vitamin B12 is produced exclusively by microorganisms and is therefore rarely found in plant-based foods. The active B12 forms are found almost exclusively in animal products; fermented products or algae sometimes provide analogs without confirmed B12 activity.¹, ²

The Role of Vitamin D – Not Just Relevant for Vegans

Besides willpower, your success also depends on your motivation: it's your starting point and your guide on the path to your goal, and it gives your actions meaning . This meaning is the crucial impetus to get started. After that, willpower takes over, enabling you to concentrate despite distractions and to translate your plans into concrete actions.

Problems arise when willpower is constantly expected to take on tasks that actually require energy, security, and regeneration. Then it becomes overstretched – much like a battery that is constantly used but never properly recharged.

When is vitamin D requirement particularly high for vegans?

Seasonal fluctuations are pronounced. Without fish and fortified products, additional sources are eliminated, which – depending on sun exposure – increases the likelihood of suboptimal levels.⁹, ¹⁰

Frau des oberen mittleren Alters, die in der Sonne steht, sportlich, Vitamin D in der Sonne tankt

Diagnostics & Procedure: Determine 25-OH-Vitamin D

Determine 25-OH-Vitamin D; consider season; use moderate sun exposure, fortified foods and – where appropriate – supplementation to achieve clinically agreed target ranges.⁹, ¹⁰

Omega-3 Fatty Acids – EPA/DHA Deficiency: A Particular Challenge for Vegan Diets

Why are omega-3 fatty acids important? EPA and DHA are structural components of cell membranes, modulate inflammatory processes, affect cardiovascular risks, and are relevant for brain and visual performance.¹¹ The influence of Omega-3 fatty acids, especially EPA and DHA, on heart health and other bodily functions is scientifically proven and plays a central role in a balanced immune system and the prevention of chronic diseases.

Challenge: Plants primarily provide ALA; the conversion of ALA → EPA/DHA is limited and varies individually (genetics, n-6/n-3 ratio, gender, metabolic state).¹¹, ¹² A purely ALA-based strategy does not reliably achieve adequate EPA/DHA levels for everyone.

Challenge: Plants primarily provide ALA; the conversion of ALA → EPA/DHA is limited and varies individually (genetics, n-6/n-3 ratio, gender, metabolic state).¹¹, ¹² A purely ALA-based strategy does not reliably achieve adequate EPA/DHA levels for everyone. to reach clinically agreed target ranges.⁹, ¹⁰

As a vegan, how do I practically integrate omega-3 fatty acids into my diet?

Incorporate ALA sources daily (flaxseed, chia seeds, walnuts).
Consider algal oil as a vegan direct source of EPA/DHA, especially during periods of increased need (e.g., pregnancy/lactation), high cognitive/athletic demands, or inflammatory conditions.¹¹, ¹³ According to current recommendations, the recommended amounts of EPA/DHA are approximately 250–500 mg per day, which should be considered when selecting and dosing algal oil supplements.
Optional: Omega-3 Index (EPA+DHA in erythrocytes) for status monitoring.¹¹

Iron - Heme Iron vs. Non-Heme Iron: Keeping Bioavailability in Mind for a Vegan Diet

Heme iron, which is only found in animal products, is better absorbed; non-heme iron from plant-based foods is less well absorbed, with absorption highly dependent on meal components.¹⁴ The functions of iron in the body primarily include oxygen transport in the blood and support of energy metabolism.

Vegetarian Iron Sources: Foods that Promote & Inhibit Absorption

Certain foods promote iron absorption: Vitamin C (e.g. citrus, berries, peppers), soaking/sprouting/souring (reduces phytates).

Certain foods inhibit iron absorption: Phytates (whole grains, legumes), polyphenols (coffee/tea), calcium simultaneously with iron source.¹⁴, ¹⁵

Vegan iron deficiency and other groups at risk

Beyond the needs of vegans, women of childbearing age have an increased risk of iron deficiency (menstrual blood loss).¹⁶ Vegan athletes with high training volumes should also take their intake planning seriously.

Iron Diagnostics & Procedure: CRP Inflammation Marker & Hemoglobin

Ferritin (storage) + CRP (inflammation marker) as well as hemoglobin/MCH/MVC. No blanket supplementation: supplement only if a deficiency is confirmed; otherwise, specifically optimize diet and absorption.¹⁴,¹⁶

Selenium: why many people buy this micronutrient

Whenever you resist temptation or motivate yourself to train, your brain is working at full capacity. The anterior mid-cingulate cortex (aMCC) plays a central role in this process: This brain region continuously assesses the expected effort required for challenging tasks and whether the effort is worthwhile in relation to the potential reward.

If this internal cost-benefit analysis is positive, the aMCC supports you in taking action and staying on track. If it's negative, for example because you're tired or stressed, it tends to hold you back. That's why old patterns often return precisely when the workload increases. The training plan gets neglected, distractions become more appealing, and quick energy boosts suddenly seem more attractive than long-term goals. Not because of a lack of willpower, but because your body switches into conservation mode .

This isn't an internal failure, but a biological self-protection mechanism. Your system is signaling: "Currently, there isn't enough energy."

Selenium supply, how & which foods?

The selenium content of plant-based foods varies greatly depending on the soil; in parts of Europe, these are low in selenium. Vegan diets can be undersupplied, depending on the choice and origin, but do not have to be.¹⁸, ¹⁹

Variety in grains, nuts/seeds, mushrooms; Brazil nuts only consciously (highly fluctuating selenium content). In case of suspicion, consider laboratory control (e.g., serum/plasma selenium, functional markers) and targeted, temporary supplementation, no automatism.¹⁸, ¹⁹

Iodine (Iod) Effect - essential for the thyroid gland

Iodine is a component of T3/T4; central for energy metabolism, thermoregulation and brain development. Among the most important functions of iodine in the body is supporting thyroid hormone production, which in turn regulates metabolism and controls numerous biochemical processes.²⁰

Iodine in Vegan Diets, which Foods Help?

When following a vegan diet, a loss of classic iodine sources is often observed (fish, dairy products). Plant-based foods contain fluctuating amounts of iodine; without iodized salt, the risk of deficiency increases.²⁰, ²¹

Algae: Iodine content can be extremely high and is difficult to quantify. No general recommendation, at most standardized products with a declared iodine content.²¹

Practical tips: Use iodized table salt sparingly; incorporate iodine-containing plant-based foods; if uncertain, consider diagnostics (e.g., iodine excretion) and make individual decisions.²⁰, ²¹

Calcium & Bones in a Vegan Diet

Stress impairs the prefrontal cortex, the brain region responsible for willpower and self-control.³ Chronic stress also shifts your body's priorities from long-term goals to immediate needs.⁴ In this state, willpower is unavailable—it is simply biologically blocked. Perseverance then feels not only difficult but almost impossible. This isn't because you lack discipline, but because your energy reserves for self-control and planning become depleted.

That's why many people like to rely on routines : automatisms largely occur without active control of the prefrontal cortex and save mental capacity. New behaviors or unfamiliar tasks, on the other hand, constantly require new decisions and cost significantly more energy. The result: your body resists the unfamiliar because it demands too much effort.

In this context, neurotransmitters such as serotonin are often discussed. This refers to substances involved in emotional stability and inner peace. Substances like 5-HTP , a precursor to serotonin, are therefore sometimes discussed as a complementary component. The focus here is less on "more willpower" and more on whether the fundamental prerequisites for self-regulation are adequately supported. A similar principle applies to certain nutrients involved in metabolic and nervous system processes. They do not replace routines or behavioral changes, but can help create the environment in which perseverance becomes possible in the first place.

Vegan, Calcium-Rich Foods & Their Connection to Vitamin D

Plant sources and bioavailability: Fortified drinks (calcium), tofu with calcium sulfate, calcium-rich vegetables (e.g. kale, bok choy, broccoli), nuts/seeds. Oxalate-rich vegetables (spinach, rhubarb) inhibit absorption, while cruciferous vegetables are more favorable.²², ²³

Vitamin D status and mechanical stress (strength training/impact) are crucial for bone balance.²², ²³ To absorb calcium from the gut, you need vitamin D.

How do I get enough protein as a vegan?

Quantity vs. Pattern: In addition to the amount of protein, the amino acid profile, particularly leucine as a trigger for muscle protein synthesis, is important. Various plant-based protein sources such as legumes, grains, nuts, and seeds play a central role in ensuring protein supply in a vegan diet. Individual plant-based sources do not always provide all essential amino acids in the optimal ratio.²⁴, ²⁵

Proteins have been shown to contribute to the growth and maintenance of muscle mass and the maintenance of normal bones. As central building blocks of the body, they make up about 15–20% of body mass and fulfill diverse structural and functional tasks – from tissue stability to enzymatic processes to transport and signaling mechanisms in metabolism. Especially when there is an increased need, a high-quality, plant-based protein source can therefore be a practical supplement to the daily diet.

How good are vegan protein shakes?

Combinations (legumes + grains; supplemented with nuts/seeds) improve the profile. For physically active individuals, the elderly, or people with restrictive food choices, it is worth paying attention to protein quality (EAA profile, leucine content) and sufficient total protein.²⁴, ²⁶ During periods of high training volume or reduced energy intake, a targeted protein increase can be beneficial, preferably through whole foods, and additionally through high-quality vegan protein blends if it helps practically.

Combinations of rice and pea protein are useful because their amino acid profiles complement each other and can thus achieve a complete profile. A protein quality with a Chemical Score of 110 and a PDCAAS of 1.0 indicates that all essential amino acids are present in at least reference-level quantities and that digestibility is very good.

In terms of taste, such blends can be enhanced with real fermented berries. Fermentation creates harmonious, fruity aromas that offer natural flavor diversity. Additionally, fruit powders such as wild blueberry, raspberry, and baobab powder can be used to incorporate plant-based co-factors in addition to the aroma.

What deficiency occurs with a vegan diet?

Current findings show that willpower is like a muscle – it needs not only a mental foundation but also a strong body to be truly resilient. Regular exercise is one of the most effective ways to build the physical prerequisites for greater willpower.

Physical activity not only trains your body, but also your "willpower muscles": it helps reduce stress, stabilizes your motivation, and strengthens your confidence in your own abilities. Exercise not only increases your physical resilience, but also your ability to persevere when faced with challenges.⁵ – just like a muscle that gets stronger through regular training.

The challenge: While increased physical activity improves willpower, it also requires discipline and motivation. That's precisely why easy entry points, fixed time slots, and low barriers are crucial to making exercise itself a supportive routine.

Find out in our sports blog which vitamins and amino acids are best suited for your physical activities.

Prevention instead of Reaction – How Vegan Deficiencies Can Be Avoided

1) Deliberate & Conscious Food Choices Among Vegans

Colorful, varied, and as unprocessed as possible: Legumes, whole grains, nuts/seeds, colorful vegetables/fruits, fortified products (e.g., drinks with calcium/vitamin D), iodized salt. Milk alternatives play an important role in a vegan diet as they can contribute to protein, vitamin, and mineral supply – attention should be paid to the ingredient lists and quality of these products. Phytate management through soaking/germinating/souring improves mineral availability.

2. Why Vegans Should Combine Plant-Based Proteins

Legumes + grains, supplemented with nuts/seeds; protein distribution throughout the day, every meal "protein-conscious." Proteins perform important functions in the body, such as muscle building, enzyme formation, and supporting numerous biochemical processes. In cases of higher demand (sport, age, weight reduction), ensure protein quality and sufficient total amount.²⁴,²⁶

3. What regular lab tests are important for vegans?

Pragmatic basis (e.g., 1–2 times/year or when symptoms appear):

Vitamin B12 status (B12 + holotranscobalamin; possibly MMA/homocysteine)¹
25-OH-Vitamin D (consider the season)⁹
Iron status (ferritin + CRP, Hb)¹⁶
Thyroid function (TSH ± fT4/fT3) and iodine history²⁰
Context-dependent: Selenium status, omega-3 index (EPA+DHA in erythrocytes)¹¹, ¹⁸

Regular monitoring of these blood values provides important results that help to adjust diet and supplementation in a targeted manner.

Which supplements are useful for vegans?

You can get the necessary energy boost from your diet. In particularly stressful phases, when willpower and self-discipline are especially important, targeted support with vitamins and nutrients can also give your body the necessary energy boost to persevere and cope better with stress.

Supplements don't replace healthy routines , but they can help stabilize existing resources. Omega-3 fatty acids and antioxidants are particularly relevant in this regard. Omega-3 fatty acids support cell and brain function, while antioxidants help the body cope with oxidative stress – a common consequence of chronic stress.

What supplements do many vegans buy?

Vitamin B12: Mandatory for a vegan diet – form and dosage individually, but consistently supplied. Recommended amounts are usually 250–500 µg daily as a supplement, depending on the preparation and absorption capacity.¹, ² ,⁸
Vitamin D: Depending on sun exposure and season; define target ranges and supplement as needed. For adults, amounts of 800–2000 IU daily are recommended, depending on individual status.⁹, ¹⁰
Omega-3: Consider algae oil (EPA/DHA) as a vegan direct source, especially with increased demand or low ALA→EPA/DHA conversion.¹¹,¹³
Iron: Supplement only after diagnosis; otherwise optimize diet/absorption strategy (Vitamin C, separate inhibitors).¹⁴,¹⁶
Iod & Selenium: No automatism; depending on dietary history, region and possibly laboratory, supplement specifically and for a limited time.¹⁸,²¹
Calcium: Preferably through diet (incl. fortified products); if consistently too low, consider supplementing, check Vitamin D status as well.²², ²³

What should be considered regarding the quality and bioavailability of vegan supplements?

Pay attention to declared contents, stability, and meaningful compounds (e.g., low-oxidation algae oil with specified EPA/DHA content; common, well-researched B12 forms). The various supplements perform different functions in the body by controlling, supporting, or regulating important biological and biochemical processes. The goal is a reliable supply, not maximum high dosage.

Conclusion – Implementing a vegan diet safely and sustainably

Willpower is one thing. A sustainable foundation is another, allowing you to pursue your goals with motivation and energy. The question is: How do you create the conditions so that your body provides you with the necessary energy?

For this, you need systems that support you in staying on track and reduce your decision-making burden. This isn't about rigid self-control, but about perseverance and consistency, so that the action becomes easier, more predictable, and more rewarding, and your body reliably tackles the task despite adverse circumstances.

The better your systems function, the less often you need to rely on willpower. And that's precisely what makes change possible in the long run.