A vegan or plant-based diet has documented benefits for cardiovascular health, longevity, and environmental sustainability — but it also comes with real nutritional risks that no amount of "just eat more greens" can fully solve. Peer-reviewed research from the NIH, Harvard T.H. Chan School of Public Health, and the Academy of Nutrition and Dietetics has identified 8 specific nutrients that vegans and plant-based eaters are statistically more likely to be deficient in. Being aware of these gaps — and knowing how to close them — is the single most important step you can take to make a plant-based diet work long-term without compromising your health.
The 8 nutrients vegans most commonly miss
Based on published nutritional research, the 8 nutrients plant-based eaters most often fall short on are: Vitamin B12, Vitamin D, Omega-3 (EPA and DHA), Iron, Zinc, Iodine, Calcium, and Choline. Some can be closed through careful food choices; others realistically require a well-formulated multivitamin or targeted supplement.
The rest of this article explains each nutrient — why vegans commonly fall short, what the science actually says, symptoms of deficiency, and how to close each gap.
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What this article covers
- Vitamin B12 — the most critical one
- Vitamin D — especially in northern climates
- Omega-3 (EPA and DHA) — the conversion problem
- Iron — different form, harder to absorb
- Zinc — hidden in phytates
- Iodine — the often-ignored nutrient
- Calcium — not just a dairy issue
- Choline — the "forgotten" essential nutrient
- How to close all 8 gaps efficiently
- Frequently asked questions
1. Vitamin B12 — the most critical nutrient for every vegan
Vitamin B12 is the single most important nutrient for anyone following a strict plant-based diet. Not because it's the most likely to cause immediate symptoms, but because deficiency can cause permanent, irreversible neurological damage if left uncorrected for years [1].
Why vegans are at high risk
B12 is produced by bacteria, not by plants or animals directly. Animals accumulate B12 through the food they eat and the bacteria in their gut, then pass it to humans through meat, dairy, and eggs. Plants contain essentially zero bioavailable B12. Claims that spirulina, nutritional yeast (unfortified), or fermented foods provide B12 have been consistently debunked by peer-reviewed research [2].
The Academy of Nutrition and Dietetics states plainly: "Vegans need reliable sources of vitamin B12, such as fortified foods or supplements. Failure to consume regular sources of B12 places vegans at risk for developing B12 deficiency."
Symptoms of B12 deficiency
- Persistent fatigue and low energy
- Numbness or tingling in hands and feet
- Difficulty concentrating or "brain fog"
- Balance problems
- Depression or mood changes
- Pale skin
- Sore, red tongue
- Memory problems
Critical warning: Folate (also common in vegan diets) can mask B12 deficiency in blood tests, making the deficiency worse over time even as blood work "looks fine." This is why relying on standard blood tests alone is not sufficient — B12 status should be checked with active B12 (holotranscobalamin) or methylmalonic acid (MMA) testing.
How much do you actually need?
The NIH RDA for B12 is 2.4 mcg per day for adults, but this is the minimum to prevent deficiency — not the optimal amount. For vegans specifically, most nutrition researchers recommend significantly higher intakes because:
- Absorption is inefficient — only about 1-2% of a large oral dose is absorbed
- Older adults absorb less — stomach acid decreases with age, reducing B12 uptake
- Common medications block absorption — PPIs, H2 blockers, metformin all reduce B12 uptake [3]
Independent supplement analysts frequently reference 250 mcg as a functional minimum for vegans with absorption challenges, and many recommend even higher for those over 50.
Best B12 form
Methylcobalamin is the naturally active form your body uses directly. Cyanocobalamin is a synthetic form that must be converted (and produces a small amount of cyanide as a byproduct, which is a non-issue at supplement doses but still not ideal). Look for methylcobalamin on your supplement label.
How to close the B12 gap
- Take a daily supplement providing at least 25 mcg of methylcobalamin, or a weekly dose of 2,000 mcg
- Consume fortified foods (nutritional yeast labeled "fortified," plant milks, some cereals)
- For older adults or those on PPIs, consider a sublingual liquid form — bypasses the acid-dependent absorption pathway [4]
- Get blood tests annually to verify status
2. Vitamin D — the "sunshine vitamin" most people don't get enough of
Vitamin D isn't strictly a "vegan issue" — the NIH estimates that approximately 41% of American adults are deficient, regardless of diet [5]. But vegans face additional challenges because most naturally occurring D3 in the food supply comes from fish, egg yolks, and fortified dairy.
Why vitamin D matters more than most people think
Vitamin D isn't just for bones. It's involved in:
- Calcium absorption (without adequate D, you don't absorb calcium properly regardless of intake)
- Immune function
- Muscle function and strength
- Mood regulation (research links deficiency to depression)
- Cardiovascular health
Symptoms of deficiency
- Frequent illnesses or infections
- Fatigue and low energy
- Bone pain or muscle weakness
- Mood changes, especially in winter
- Hair loss
- Slow wound healing
How much do you need?
The NIH RDA is 15-20 mcg (600-800 IU) per day. However, clinical research suggests that maintaining adequate blood levels typically requires 1,000-2,000 IU per day for most adults — particularly those with limited sun exposure, darker skin, or living above 37° latitude (which includes most of North America and Europe).
D2 vs D3 — an important distinction
Most plant-based D supplements historically used D2 (ergocalciferol) from mushrooms. Research has consistently shown that D3 (cholecalciferol) is significantly more effective at raising and maintaining blood levels than D2 [6]. Fortunately, vegan D3 is now widely available from two sources:
- Lichen-derived D3 (like Vitashine)
- Plant-cultivated D3 (like VegaD3+ used in The Vitamin Shots)
Both are fully vegan and as bioavailable as animal-derived D3. Always check that your vegan multivitamin uses D3, not D2.
How to close the vitamin D gap
- Sunlight: 15-20 minutes of direct midday sun on face and arms, several times per week (limited by climate, skin tone, and season)
- Fortified foods: Fortified plant milks, orange juice, cereals
- Supplement: 1,000-2,000 IU of vegan D3 daily — the most reliable option, especially in winter
- Get tested: A simple blood test (25-hydroxyvitamin D) tells you your actual status
3. Omega-3 (EPA and DHA) — the conversion problem no one warns vegans about
This is arguably the most misunderstood nutrient gap in the plant-based world. Many vegans believe they get "plenty of omega-3" from flaxseed, chia, and walnuts. Technically true — but nutritionally incomplete, and the reason matters.
The three types of omega-3
There are three primary omega-3 fatty acids:
- ALA (alpha-linolenic acid) — found in flax, chia, walnuts, hemp
- EPA (eicosapentaenoic acid) — found in fatty fish and algae
- DHA (docosahexaenoic acid) — found in fatty fish and algae
Only EPA and DHA are directly used by the body for cardiovascular, brain, and eye function. ALA is technically a precursor that can be converted to EPA and DHA — but this conversion is remarkably inefficient in humans.
The conversion problem — actual numbers
Published research indicates:
- Only about 5-10% of ALA is converted to EPA in most adults [7]
- Less than 1% of ALA is converted to DHA in most adults
- Conversion rates are even lower in men and in people with certain genetic variants
This means eating flaxseed daily provides plenty of ALA, but nowhere near enough EPA and DHA for optimal function — regardless of how much flax you eat.
Why EPA and DHA matter
These are the omega-3 forms actually studied in clinical research for [7]:
- Cardiovascular health — supports healthy triglyceride levels
- Brain function — DHA is a major structural component of brain tissue (approximately 25% of brain fat is DHA)
- Eye health — DHA is concentrated in the retina
- Inflammation regulation
- Mood and cognitive function
Vegan sources of EPA and DHA
Two options — both plant-based:
- Algae oil supplements — algae is what fish eat to accumulate their omega-3s. Cuts out the middleman. Available as DHA-only or EPA+DHA combined.
- Ahiflower seed oil — provides SDA (stearidonic acid), which the body converts to EPA at 20-30% efficiency (versus 5-10% for ALA). Provides broader Omega 3-6-9 spectrum.
How much do you need?
The NIH does not have an official RDA for EPA and DHA specifically, but most clinical research suggests 250-500 mg combined EPA + DHA per day for general health, and 1,000+ mg per day for cardiovascular or mood support.
How to close the omega-3 gap
- Take an algal oil supplement — 250-500 mg combined EPA and DHA daily
- Or use a multivitamin that includes EPA and DHA built in — few do, so check the label
- Continue eating flax/chia/walnuts for ALA and general fat balance, but don't rely on them alone
4. Iron — same amount, worse absorption
Interestingly, vegans often consume MORE iron than omnivores — through beans, lentils, tofu, spinach, and fortified grains. Yet iron deficiency is still more common in vegans, particularly menstruating women [8]. The reason is absorption.
Heme vs non-heme iron
There are two types of dietary iron:
- Heme iron — found only in animal products. Absorbed at 15-35% efficiency.
- Non-heme iron — found in plants. Absorbed at just 2-20% efficiency.
Vegans get only non-heme iron, which is affected by absorption inhibitors (phytates, tannins, calcium) present in the same plant foods that provide the iron in the first place.
Who is at highest risk
- Menstruating women
- Pregnant women
- Endurance athletes
- Teenagers
- People with heavy periods
Important nuance for men: Adult men without documented deficiency generally do NOT need iron supplementation. In fact, excess iron in men has been associated with increased health risks, since the body has no efficient way to excrete excess iron. This is why many men's multivitamins deliberately exclude iron or use modest doses.
Symptoms of iron deficiency
- Persistent fatigue
- Pale skin
- Shortness of breath
- Cold hands and feet
- Brittle nails
- Restless legs
- Hair loss
How to close the iron gap (if needed)
- Eat iron-rich plants: lentils, beans, tofu, tempeh, quinoa, dark leafy greens, fortified cereals
- Pair with vitamin C: vitamin C in the same meal can increase non-heme iron absorption up to 3x
- Avoid coffee/tea with iron-rich meals: tannins can cut absorption by up to 50%
- Consider cast-iron cookware: genuinely adds trace amounts of iron to food
- Supplement only if tested-and-confirmed deficient: don't self-supplement iron without a blood test, especially men
5. Zinc — trapped inside plant phytates
Zinc deficiency in vegans is subtle but common. Plants like grains and legumes contain phytates (phytic acid), which bind to zinc in the intestine and prevent absorption. Vegans typically consume more zinc than omnivores, but bioavailability is significantly lower [9].
Why zinc matters
- Immune function
- Wound healing
- Testosterone production (particularly relevant for men)
- Taste and smell
- DNA synthesis
- Cell growth and division
Symptoms of deficiency
- Frequent colds and infections
- Slow wound healing
- Hair thinning or hair loss
- Loss of taste or smell
- Poor concentration
- Skin issues (acne, eczema)
How to close the zinc gap
- Best plant sources: pumpkin seeds, hemp seeds, cashews, chickpeas, lentils, oats, quinoa
- Reduce phytates: soaking, sprouting, and fermenting grains and legumes reduces phytate content and increases zinc absorption
- Vegan RDA is higher: the Institute of Medicine suggests vegans may need up to 50% more zinc than the standard RDA due to reduced absorption
- Consider a multivitamin that includes zinc if dietary intake is inconsistent
6. Iodine — the nutrient everyone forgets
Iodine is essential for thyroid hormone synthesis, and vegans are at particular risk of deficiency because the main dietary sources — iodized salt, seafood, and dairy — are either avoided or replaced with non-iodized alternatives.
Why this is a growing problem
Iodine deficiency was largely eliminated in developed countries through iodized salt in the 20th century. But modern trends have reversed this:
- Sea salt, Himalayan salt, and kosher salt (popular in health-conscious kitchens) contain little to no iodine
- Processed foods increasingly use non-iodized salt
- Vegans avoid dairy and seafood — the primary non-salt iodine sources
Recent research suggests iodine deficiency is silently returning, particularly among health-conscious vegans who use pink salt.
Why iodine matters
- Thyroid hormone production (T3, T4)
- Metabolism regulation
- Brain development in fetuses (critical during pregnancy)
- Energy production
Symptoms of deficiency
- Fatigue and weakness
- Weight gain
- Cold intolerance
- Dry skin and hair
- Enlarged thyroid (goiter)
- Slow metabolism
- Depression
How to close the iodine gap
- Best vegan sources: seaweed (kelp, nori, wakame — small amounts, since seaweed can also contain too much iodine)
- Use iodized salt occasionally if you don't already
- Supplement: the NIH RDA is 150 mcg per day. Look for iodine in your multivitamin — many family formulas exclude it entirely
Caution: Excess iodine can also cause thyroid problems. Stick to the RDA unless directed otherwise by your doctor.
7. Calcium — it's not just about milk
The myth that vegans can't get enough calcium is partly outdated — many plant foods are excellent calcium sources. But the myth exists for a reason: plant calcium absorption varies widely, and total intake among vegans often falls short of the RDA [10].
Why calcium matters
- Bone density and strength
- Muscle contraction (including heart)
- Nerve signaling
- Blood clotting
- Enzyme function
Best plant sources of calcium
- Fortified plant milks (soy, almond, oat) — often provide 25-30% DV per cup
- Tofu made with calcium sulfate — check the label
- Dark leafy greens (collard greens, kale, bok choy — spinach has calcium but low absorption due to oxalates)
- Tahini and sesame seeds
- Fortified orange juice
- Almonds
The vitamin D-calcium connection
Even the best calcium intake is wasted without adequate vitamin D — which is required for calcium absorption. This is why vegan multivitamin formulas frequently pair calcium with D3.
How to close the calcium gap
- Include at least 2-3 servings of high-calcium plant foods daily
- Ensure adequate vitamin D intake (see section 2)
- Consider a multivitamin that includes calcium — noting that many minimalist or family formulas exclude it
8. Choline — the essential nutrient no one talks about
Choline is one of the least-discussed but most commonly deficient nutrients in the US population — and vegans are at particular risk. Research indicates more than 90% of Americans fall short of adequate choline intake [11], and the plant-based population fares even worse because top choline sources are eggs, liver, and dairy.
Why choline matters
- Brain function and memory — precursor to acetylcholine, a critical neurotransmitter
- Liver function — helps prevent fat accumulation in the liver
- Cell membrane integrity — component of phosphatidylcholine, essential for every cell
- Fetal brain development — critical during pregnancy
- Metabolism of homocysteine — related to cardiovascular health
Symptoms of deficiency
- Memory problems and brain fog
- Fatigue
- Mood changes
- Muscle weakness or damage
- Non-alcoholic fatty liver disease (in severe deficiency)
Best plant sources of choline
- Soybeans and tofu
- Quinoa
- Broccoli
- Brussels sprouts
- Cauliflower
- Wheat germ
- Peanuts
The catch: even excellent plant sources contain modest choline amounts compared to eggs (which have ~150 mg per egg). A vegan would need to consume large portions of choline-rich plants daily to reach adequate intake.
How much do you need?
The NIH Adequate Intake is 550 mg per day for men and 425 mg per day for women. Most vegans get far less than this from diet alone.
How to close the choline gap
- Include soy foods, quinoa, and cruciferous vegetables regularly
- Consider a supplement — very few multivitamins include choline, so read labels carefully
- Choline bitartrate is the most common supplement form
How to close all 8 gaps efficiently — without taking 10 pills a day
Now that you understand the science, the practical question becomes: how do you actually address all 8 gaps without overwhelming your daily routine?
The three realistic approaches
Approach 1: Diet-only optimization. Possible for some nutrients (iron, zinc, calcium, choline) with careful meal planning. Not realistic for B12 (essentially zero in plants) or EPA and DHA (conversion too inefficient). Requires nutritional literacy and daily discipline.
Approach 2: Multiple targeted supplements. Buy separate B12, vitamin D, algal omega-3, iron (if needed), zinc, iodine, calcium, and choline supplements. Effective but expensive and involves taking multiple pills or drops daily. Adherence tends to drop over time.
Approach 3: A well-formulated comprehensive vegan multivitamin. Efficient in principle, but here's the honest reality — very few multivitamins actually contain all 8 nutrients in meaningful doses. Most vegan multivitamins skip EPA and DHA, and family formulas often exclude iron, calcium, and iodine.
What to look for in a comprehensive vegan multivitamin
If you choose Approach 3, look for a formula that includes:
- ✅ Methylcobalamin B12 — at least 25 mcg (higher for older adults)
- ✅ D3 (not D2) from vegan sources like lichen or plant-cultivated — at least 1,000 IU
- ✅ EPA and DHA from algal oil or Ahiflower seed oil — most multis skip this entirely
- ✅ Iron (unless a men's formula deliberately excluding it) — modest doses of 2-8 mg are appropriate for most
- ✅ Zinc — 8-11 mg
- ✅ Iodine — 150 mcg
- ✅ Calcium — at least a meaningful contribution to daily needs
- ✅ Choline — at least 100+ mg (very few multis include this)
Most popular vegan multivitamins miss 3-5 of these. The Vitamin Shots was formulated specifically to address all 8 gaps in a single daily serving, including EPA + DHA and choline that most competitors omit. For readers who prefer a different delivery format, we also offer Vitamin Sprinkles — a companion product with a distinct absorption profile. Full product line at thevitaminshots.com.
Regardless of which product or approach you choose, the most important thing is consistency. The best supplement is the one you'll actually take every day, for years — because most of these nutrient gaps develop over months and correct over months.
Get tested — the smartest move
Before starting any supplement regimen, consider getting a baseline blood test. Ask your doctor for:
- Vitamin B12 (holotranscobalamin or MMA for accuracy)
- 25-hydroxyvitamin D
- Ferritin (iron stores)
- Complete blood count (CBC)
- TSH (thyroid function, indirectly assesses iodine)
Then retest after 3-6 months of dietary changes and supplementation. This is the only way to know if your approach is actually working.
Frequently asked questions
Do vegans really need to supplement B12?
Yes. Vitamin B12 is not reliably found in plant foods in bioavailable forms. Every major nutrition authority — including the NIH, the Academy of Nutrition and Dietetics, the British Dietetic Association, and the Vegan Society — recommends that vegans consume regular fortified foods or a B12 supplement. B12 deficiency can cause permanent neurological damage if left uncorrected.
Can I get enough omega-3 from flaxseed and chia?
Not for EPA and DHA specifically. Flaxseed, chia, and walnuts provide ALA (alpha-linolenic acid), which the body converts to EPA at only 5-10% efficiency and to DHA at less than 1%. This is not enough for optimal cardiovascular, brain, and eye function. Vegans should consider an algal oil supplement or a multivitamin that includes EPA and DHA directly.
Should men take iron supplements?
Adult men without documented iron deficiency generally should NOT take iron supplements. The NIH RDA for men is 8 mg per day, which most diets provide. Because the body cannot efficiently excrete excess iron, buildup over time has been associated with increased health risks. This is why many men's multivitamins deliberately exclude or minimize iron. Women, particularly menstruating women, have different requirements and should discuss iron with their doctor.
Is choline really that important?
Yes. Choline is officially classified as an essential nutrient by the NIH, and research indicates over 90% of Americans fall short of the Adequate Intake. It's critical for brain function, liver health, and cell membrane integrity. Because top dietary sources are eggs, liver, and dairy — foods vegans avoid — this is one of the largest hidden gaps in plant-based nutrition. Most vegan multivitamins do not include meaningful choline doses, so read labels carefully.
What's the difference between D2 and D3?
D2 (ergocalciferol) is derived from plants and mushrooms; D3 (cholecalciferol) is traditionally derived from lanolin (sheep's wool) but is now also available from vegan sources like lichen or plant cultivation. Research consistently shows D3 is significantly more effective at raising and maintaining blood vitamin D levels than D2. Vegans should look for vegan D3 (like Vitashine or VegaD3+), not D2.
How long does it take to correct a nutrient deficiency?
It depends on the nutrient and the severity of the deficiency. Mild deficiencies typically correct in 4-12 weeks of consistent supplementation. Severe deficiencies (particularly B12 and iron) may take 3-6 months or longer to fully normalize blood markers. Symptomatic improvement often precedes complete lab correction. Retest at 3 and 6 months to confirm your approach is working.
Can I get everything from food if I plan carefully?
Partially, but not completely. B12 is essentially impossible to get from unfortified plant foods in adequate amounts — supplementation or fortified foods are non-negotiable. EPA and DHA are extremely difficult to get in adequate amounts without algal oil supplementation, since the conversion from plant ALA is inefficient. The other nutrients (iron, zinc, calcium, choline, iodine, vitamin D) can theoretically be obtained through very careful meal planning, but consistency is difficult, and most vegans still fall short in real-world eating patterns. A comprehensive multivitamin provides a reliable safety net.
Which nutrient should I prioritize if I can only address one?
Vitamin B12 without question. B12 deficiency is the only nutrient gap on this list that can cause permanent neurological damage if untreated for years. Every vegan should be taking either a B12 supplement or consuming reliably fortified foods on a regular basis. This is not optional.
Do I need to take supplements forever if I'm vegan?
For B12 and typically vitamin D — yes, as long as you follow a plant-based diet with limited sun exposure. For the other nutrients (iron, zinc, calcium, iodine, choline, omega-3), it depends on your specific diet and lifestyle. Regular blood testing every 6-12 months tells you which supplements you genuinely need and which you may be able to reduce.
Are gummies or liquid multivitamins as effective as pills?
Format matters less than formulation. Liquid multivitamins can offer partial sublingual absorption (particularly helpful for B12 in older adults), and can be easier to take consistently. Gummies tend to have lower nutrient doses due to size constraints and often exclude harder-to-formulate ingredients like iron and omega-3s. Pills allow the highest doses but require adequate stomach acid for absorption. The best format is the one you'll actually take every day.
References & sources
- National Institutes of Health, Office of Dietary Supplements. Vitamin B12 — Fact Sheet for Health Professionals. ods.od.nih.gov
- Watanabe F, Yabuta Y, Bito T, Teng F. Vitamin B12-containing plant food sources for vegetarians. Nutrients. 2014;6(5):1861-1873.
- Andrès E, Loukili NH, Noel E, et al. Vitamin B12 (cobalamin) deficiency in elderly patients. CMAJ. 2004;171(3):251-259.
- Sharabi A, Cohen E, Sulkes J, Garty M. Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route. British Journal of Clinical Pharmacology. 2003;56(6):635-638. pubmed.ncbi.nlm.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Vitamin D — Fact Sheet for Health Professionals. ods.od.nih.gov
- Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status. American Journal of Clinical Nutrition. 2012;95(6):1357-1364.
- National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids — Fact Sheet for Health Professionals. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Iron — Fact Sheet for Health Professionals. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Zinc — Fact Sheet for Health Professionals. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Calcium — Fact Sheet for Health Professionals. ods.od.nih.gov
- Wallace TC, Fulgoni VL. Assessment of Total Choline Intakes in the United States. Journal of the American College of Nutrition. 2016;35(2):108-112.
- Academy of Nutrition and Dietetics. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. Journal of the Academy of Nutrition and Dietetics. 2016;116(12):1970-1980.