If you eat vegan, you consume no animal products. That reduces the risk of certain diseases — but it also creates specific nutrient gaps, depending on how well you plan. A well-planned vegan diet is safe. A poorly planned one is not. This article shows you which blood values to check regularly and what you can do about them.
No pro- or anti-vegan agenda here — just facts, numbers and action steps.
What Sets Vegan Eating Apart
Vegan means no animal products at all: no meat, no fish, no dairy, no eggs, no honey. Plant-based eating is broader — it allows occasional animal foods.
The biological issue: some nutrients are found primarily or exclusively in animal foods. Others are present in plants but with significantly lower bioavailability. Both create risks that stay invisible without monitoring — deficiency symptoms often appear only years later.
For the basics of reading your lab results, check the guide on understanding blood values.
Critical Nutrients at a Glance
| Nutrient | Risk for vegans | Target blood value |
|---|---|---|
| Vitamin B12 | Very high — no reliable plant source | Holo-TC >50 pmol/l, MMA <271 nmol/l |
| Omega-3 (EPA/DHA) | High — ALA barely converts | Omega-3 index >8% |
| Iron | Medium-high — lower bioavailability | Ferritin 30–150 ng/ml |
| Iodine | High — no fish, variable seaweed content | Urinary iodine 100–200 µg/l |
| Zinc | Medium — phytates inhibit absorption | 70–120 µg/dl |
| Selenium | Medium — soil-dependent | 80–150 µg/l |
| Vitamin D | Same as omnivores — sun exposure lacking | 40–60 ng/ml (25-OH) |
| Calcium | Medium — plant sources can suffice | Ionized Ca: 1.15–1.35 mmol/l |
| Choline | Often underestimated | 425–550 mg/day intake |
| Vitamin A | Beta-carotene conversion varies | Retinol 0.7–2.8 µmol/l |
Vitamin B12: The Non-Negotiable
Vitamin B12 is the single most critical nutrient on a vegan diet. There is no reliable plant-based source. Full stop.
Nori, spirulina and fermented foods contain B12 analogues (pseudo-B12) that are biologically inactive and can actually block absorption of real B12. The liver stores B12 for 3 to 5 years — which is why deficiency develops slowly and is often only detected once neurological damage has occurred.
What to supplement: 1000 µg methylcobalamin or cyanocobalamin daily. Methylcobalamin is preferred by some, but both forms are effective. Alternative: 2000 µg every two days.
What to test in the lab:
- Holo-Transcobalamin (Holo-TC): The functional B12 level. Aim for above 50 pmol/l. Below 35 pmol/l indicates deficiency.
- Methylmalonic acid (MMA): Rises before serum cobalamin drops. Keep below 271 nmol/l. MMA is more sensitive than total serum B12.
- Serum cobalamin alone is not enough — it also captures inactive B12 forms and can appear falsely normal.
Your Holo-TC is 38 pmol/l after 6 months of supplementation? In Lab2go, you see the trend and can tell whether your dose is working or whether you need to go higher.
More about B vitamins and their roles in the B vitamins complex guide.
Omega-3: Algae Oil Instead of Fish
ALA (alpha-linolenic acid) from flaxseed, walnuts and chia seeds is an omega-3 fatty acid — but it is not EPA or DHA. The body can convert ALA to EPA and DHA, but the rate is below 5 percent for EPA and below 0.5 percent for DHA. That is not enough for optimal cardiovascular health, inflammation regulation and brain function.
What to supplement: Algae oil with 500 to 1000 mg EPA+DHA daily. Algae are the original source — fish contain omega-3 because they eat algae. Algae oil is vegan and delivers the fatty acids directly.
What to test in the lab:
- Omega-3 index: Share of EPA+DHA in red blood cells. Target: above 8 percent. Below 4 percent is the cardiovascular risk zone.
Details on dosing and effects in the omega-3 dosing guide.
Iron: Bioavailability Is the Key
Plants contain iron — but as non-heme iron, which the body absorbs at a rate of 5 to 12 percent. Heme iron from meat is absorbed at 15 to 35 percent. The difference is significant.
Additional inhibiting factors in vegan diets:
- Phytates in legumes and grains bind iron and make it indigestible
- Tannins in tea, coffee and red wine inhibit absorption
- Calcium competes with iron for the same transporters
Counter-strategies:
- Vitamin C taken with the meal doubles or triples non-heme iron uptake
- Soaking and sprouting legumes breaks down phytates
- Avoid eating iron-rich and calcium-rich foods at the same meal
What to test in the lab:
- Ferritin: Target 30 to 150 ng/ml. Below 30 ng/ml means iron stores are depleted, even if hemoglobin still appears normal.
- Transferrin saturation: 15 to 50 percent. Below 15 percent indicates functional iron deficiency.
- Hemoglobin as a rough marker — drops only when deficiency is advanced.
Supplement only when needed: Do not supplement iron preventively. Excess iron is harmful. Only supplement after lab-confirmed deficiency. Details in the iron supplementation guide.
Zinc: Phytates as Antagonists
Legumes, whole grains and nuts contain zinc — but also lots of phytic acid. Phytates bind zinc in the gut and reduce uptake by 15 to 35 percent compared to an omnivorous diet.
Strategies to improve absorption:
- Soak legumes for 12 to 24 hours, discard the soaking water
- Sourdough bread instead of whole grain bread (fermentation breaks down phytates)
- Sprouted seeds and sprouts
What to test in the lab:
- Serum zinc: 70 to 120 µg/dl. Supplement if below 70 µg/dl.
- Zinc levels can drop temporarily during acute infections — do not test when ill.
Supplement: 10 to 15 mg zinc daily when deficient, take in the evening. Not at the same time as iron. Details in the zinc and selenium guide.
Iodine: Your Thyroid Needs Seawater
Fish and dairy are the main iodine sources in Europe. Both are absent from a vegan diet. Iodized salt helps but 5 g of iodized salt provides only about 100 µg — often not enough.
Seaweed varies enormously: nori and wakame contain 30 to 100 µg per serving — usable. Dried kombu can contain over 10,000 µg per serving and poses a real overdose risk for the thyroid. Not a reliable daily iodine source.
What to test in the lab:
- Urinary iodine (spot urine): 100 to 200 µg/l as a reference. Below 50 µg/l is deficient.
Supplement: 100 to 150 µg iodine daily — either as a standalone supplement or as part of a multivitamin.
Selenium, Vitamin D, Calcium, Choline
Selenium is heavily soil-dependent. Northern European soils are selenium-poor, so even omnivores often have suboptimal levels. Brazil nuts are the most natural source: 1 to 2 nuts per day provides 50 to 90 µg. More than 3 to 4 nuts daily risks toxicity. Target serum level: 80 to 150 µg/l.
Vitamin D is just as problematic for vegans as for omnivores — the main driver is lack of sun exposure, not diet. Vegan vitamin D3 is derived from lichen. Combine with K2 (MK-7, 100 to 200 µg) for calcium regulation. Target 25-OH vitamin D: 40 to 60 ng/ml.
Calcium is available from plant sources if you choose the right ones: broccoli and kale (better bioavailability than milk per calorie), almonds, sesame (tahini), calcium-set tofu, calcium-fortified plant milks. Target: 1000 mg daily. Calcium supplements at high doses increase cardiovascular risk — supplement only when diet falls short.
Choline is systematically underconsumed by vegans. It is essential for liver function, fat metabolism and the nervous system. Sources: soybeans, quinoa, cauliflower, broccoli — but the amounts rarely add up. Daily target: 425 mg (women) to 550 mg (men). Consider a supplement of 250 to 500 mg alpha-GPC or choline bitartrate.
Nutrients Found Only in Animal Foods
Creatine, L-carnitine, taurine and carnosine are absent or trace in plants. Vegans have measurably lower levels. This is not a classical deficiency — the body synthesizes these compounds — but status is low.
Creatine: Stored mainly in skeletal muscle and the brain. Vegans have 20 to 30 percent less intramuscular creatine. Supplement: 3 g creatine monohydrate daily. Effect: well-documented for physical performance and cognitive function.
L-carnitine: Synthesized from lysine and methionine. Often at the lower end of normal in vegans. Clinically relevant mainly when fatigue is present.
Taurine: Synthesized endogenously from methionine and cysteine, but in limited amounts.
Vitamin A (retinol): Not present in plants. Beta-carotene must be converted to retinol. In 30 to 45 percent of people, this conversion is significantly impaired due to BCMO1 gene variants. Someone who eats lots of carrots but converts poorly can still develop functional vitamin A deficiency.
Protein: Combination Is the Key
1.0 to 1.6 g of protein per kilogram of body weight per day. For active people and athletes: 1.4 to 1.8 g/kg.
Plant proteins often lack a complete amino acid profile:
- Grains (rice, wheat): low in lysine
- Legumes (beans, lentils): low in methionine
- Combining both over the course of the day provides all essential amino acids
Protein sources with a complete profile: soy (edamame, tofu, tempeh), quinoa, hemp seeds. These do not need to be combined.
High-Risk Groups: Who Needs Extra Attention
Pregnant and breastfeeding women. B12 deficiency can cause neurological damage in the child. Iodine deficiency impairs brain development. DHA is essential for fetal brain growth. Medical supervision and lab monitoring every 4 to 6 weeks is mandatory here — self-tracking alone is not enough.
Children and teenagers. Growth and brain development have high demands. The German Society for Nutrition recommends vegan diets for children only under medical supervision with continuous monitoring.
Endurance and strength athletes. Protein, creatine, iron and B12 are all critical. Test every 3 to 4 months. Lab2go makes biomarker tracking over time straightforward — useful for athlete-specific protocols.
Older adults. B12 absorption declines with age due to reduced intrinsic factor production in the stomach. Vegan seniors need higher doses or sublingual supplementation.
Common Myths Debunked
“Spirulina covers B12.” No. Spirulina contains pseudo-B12 that blocks absorption of the real vitamin.
“Flaxseed gives me enough omega-3.” ALA is not EPA or DHA. Conversion rates are insufficient. Algae oil is the only vegan solution for EPA and DHA.
“Spinach is a great iron source.” Spinach contains iron, but also high amounts of oxalic acid which strongly inhibits absorption. Without vitamin C and avoiding tea and coffee with the meal, very little iron is actually absorbed.
“Raw food blocks iodine absorption.” Cruciferous raw vegetables contain glucosinolates which can inhibit iodine uptake at very high intakes — but in normal amounts this is not clinically relevant.
Your Vegan Supplement Stack
This is a starting point, not a personalized recommendation. Test your blood values first, then adjust.
| Supplement | Dose | Note |
|---|---|---|
| Vitamin B12 (methylcobalamin) | 1000 µg/day | Daily, morning |
| Algae omega-3 (EPA/DHA) | 500–1000 mg/day | With a fatty meal |
| Vitamin D3 (lichen-derived) | 2000 IU/day | With K2 MK-7 100–200 µg |
| Iodine | 100–150 µg/day | If iodized salt is not used consistently |
| Zinc | 10–15 mg/day | Evening, not with iron |
| Creatine | 3 g/day | For athletes and cognitive function |
| Choline (alpha-GPC) | 250–500 mg/day | If diet falls short |
| Iron | Only when needed | Never without lab-confirmed deficiency |
Lab Monitoring Routine for Vegans
Every 6 to 12 months (every 6 months during the first year):
- Complete blood count (CBC)
- Ferritin + transferrin saturation
- Holo-Transcobalamin (Holo-TC) + MMA
- 25-OH vitamin D
- Serum zinc
- Whole blood selenium
- Urinary iodine (spot test)
- Omega-3 index
Optional, depending on symptoms:
- Copper
- Ionized calcium
- Choline/betaine
- Retinol (vitamin A)
Your first blood test after switching to vegan shows ferritin at 22 ng/ml and Holo-TC at 31 pmol/l? In Lab2go, you document that and see the trend after 6 months of supplementation. Check pricing plans — a basic panel costs 40 to 90 euros as an out-of-pocket test.
For deeper context on reading your results, see the guide on micronutrient deficiencies in bloodwork.
Summary
A vegan diet works — with monitoring. Without regular blood tests, B12 deficiency, iron deficiency and iodine deficiency are invisible until they cause symptoms. With a structured supplement stack and twice-yearly lab checks, you eliminate the risks systematically.
Three steps to get started:
- Establish a baseline. Holo-TC, MMA, ferritin, omega-3 index, 25-OH vitamin D, zinc, selenium, urinary iodine. One-time cost: 60 to 90 euros.
- Start your supplement stack. B12, algae omega-3, vitamin D3+K2, iodine. Add the rest based on your results.
- Re-test after 6 months. Verify that levels have improved. Adjust doses accordingly.
Check out Lab2go features to structure your tracking — or pick a pricing plan that fits your monitoring schedule.
This article does not replace medical advice. Pregnant women, children and people with underlying health conditions should follow a vegan diet only under medical supervision.
Article FAQ
- Which blood values are most important for vegans?
- The most critical markers are Holo-Transcobalamin (Holo-TC) and Methylmalonic Acid (MMA) for vitamin B12, ferritin and transferrin saturation for iron, 25-OH vitamin D, serum zinc, selenium, urinary iodine, and the omega-3 index. These should be tested at least once a year — twice a year during the first year on a vegan diet.
- Do vegans really need to supplement vitamin B12?
- Yes, without exception. There is no reliable plant-based B12 source. Nori, spirulina and nutritional yeast contain B12 analogues that can actually block absorption of the real vitamin. Without supplementation, stores run out within 3 to 5 years. Recommendation: 1000 µg methylcobalamin daily or 2000 µg every two days. Target lab values: Holo-TC above 50 pmol/l, MMA below 271 nmol/l.
- Is ALA from flaxseed enough as an omega-3 source?
- No. ALA (alpha-linolenic acid) from flaxseed, walnuts and chia seeds can be converted to EPA and DHA in the body — but conversion rates are below 5 percent for EPA and below 0.5 percent for DHA. That is not enough to maintain adequate EPA and DHA in tissue. Vegan algae oil capsules with 500 to 1000 mg EPA+DHA daily are the direct solution.
- Vegans eat a lot of iron from plants — why is ferritin often still low?
- Plant iron is non-heme iron. Bioavailability is 5 to 12 percent, compared to 15 to 35 percent for heme iron from meat. Phytates in legumes and grains and tannins in tea and coffee further inhibit absorption. Vitamin C taken with the meal can triple non-heme iron uptake. Drinking tea or taking calcium at the same time cancels that effect.
- How much iodine do I need on a vegan diet?
- 100 to 150 µg per day is the target range for adults. Without fish and dairy, most vegans fall short. Iodized salt helps but rarely covers the full requirement. Seaweed varies wildly — dried kombu can contain over 10,000 µg per serving and is not safe as a daily iodine source due to overdose risk. A supplement providing 100 to 150 µg iodine is the safest option.
- What about creatine, carnitine and taurine on a vegan diet?
- These compounds are found almost exclusively in animal foods. Vegans have measurably lower blood levels, though this is often clinically asymptomatic. For athletes or people with high cognitive demands, supplementation is worthwhile: creatine 3 g per day (documented performance benefit), L-carnitine if fatigue symptoms are present. Taurine is synthesized endogenously from methionine and cysteine — but only in limited amounts.
- Is a vegan diet safe during pregnancy?
- It is possible but requires medical supervision and close monitoring. Vitamin B12 deficiency can cause neural tube defects in the child. Iodine, iron, omega-3 (DHA for brain development) and calcium needs are all elevated. Self-monitoring is not enough here — gynecological and lab-based checks every 4 weeks are necessary.
- Why is vitamin A problematic on a vegan diet?
- True vitamin A (retinol) is only found in animal foods. Plant sources supply beta-carotene (pro-vitamin A), which must be converted by the body. In 30 to 45 percent of people, this conversion is significantly impaired due to genetic variants in the BCMO1 gene. Someone who eats plenty of carrots but is a poor converter can still develop functional vitamin A deficiency.
- How much protein do I need on a vegan diet?
- 1.0 to 1.6 g per kilogram of body weight per day. For active people and athletes, 1.4 to 1.8 g/kg. Plant proteins often have an incomplete amino acid profile — grains are low in lysine, legumes are low in methionine. Combining both throughout the day solves the problem. Soy, quinoa and hemp seeds provide all essential amino acids on their own.
- Can I take all vegan supplements at the same time?
- Most are fine together, but a few combinations need attention. Iron and zinc compete for the same absorption pathway — do not take together. Calcium inhibits iron absorption. Fat-soluble vitamins (D, K2) should be taken with a fat-containing meal. Take zinc in the evening, B12 in the morning. In Lab2go, you can document your stack and track interactions alongside your lab results.
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