What supplements do vegans need besides B12?
Summary
B12 is the one nutrient you can't reliably get from plant foods alone, so it's non-negotiable. Beyond that, a few nutrients deserve attention depending on your diet and where you live: vitamin D3 (especially at higher latitudes), DHA/EPA omega-3 from algal oil, and iodine if you don't use iodised salt — with zinc and calcium worth a thought depending on food choices. Most of these come from ordinary varied eating or a single daily multivitamin; only B12 is truly essential for everyone.
Supported by 9 cited sources
Key Points
- 1The plant-based omega-3 ALA (found in flaxseed, chia, walnuts, and hemp) converts to EPA and DHA in the body, but conversion rates are low — approximately 5-8% for EPA and as low as 0.5-5% for DHA, with substantial individual variation and generally higher rates in women of reproductive age (Burdge & Calder, 2005).
- 2A study of Boston-area vegans found that 80% had iodine intakes below the RDA (Leung et al., 2011).
- 3Plant foods contain zinc (legumes, nuts, seeds, whole grains), but phytates in these foods can reduce absorption by up to 50% (Melina et al., 2016).
- 4Iron deficiency is the most common nutritional deficiency worldwide, affecting omnivores and vegans alike.
- 5The EPIC-Oxford study found that vegans with calcium intakes below 525 mg/day had substantially elevated fracture risk (Tong et al., 2020). However, vegans who met adequate calcium intakes showed much less risk elevation.
Evidence Summary
The Academy of Nutrition and Dietetics confirms that well-planned vegan diets are nutritionally adequate for all life stages (Melina et al., 2016). However, "well-planned" is doing important work in that sentence. Beyond B12 — which is non-negotiable — several nutrients require conscious attention on a vegan diet.
Vitamin D3
Vitamin D deficiency is common across all dietary patterns, particularly at latitudes above 35 degrees north or south, during winter months, and among people with darker skin. Vegan-specific D3 (cholecalciferol) derived from lichen is now widely available, replacing the older D2 (ergocalciferol) supplements that had lower bioavailability (Melina et al., 2016).
DHA and EPA (long-chain omega-3 fatty acids)
While clinical deficiency is uncommon, suboptimal DHA status has been documented in vegans. DHA is important for brain health, retinal function, and may play a role in cardiovascular protection.
Iodine
Iodine status varies significantly by geography and dietary pattern. Vegans who do not consume iodised salt or sea vegetables may be at risk of deficiency.
Sea vegetables (nori, wakame) contain iodine but in highly variable amounts — kelp can contain dangerously high levels, while nori provides more modest amounts. Iodised salt is the most reliable dietary source.
Zinc
Soaking, sprouting, and fermenting foods reduces phytate content and improves zinc bioavailability.
Clinical zinc deficiency in vegans is uncommon in well-planned diets, but marginal status is possible, particularly in people relying heavily on unprocessed whole grains without preparation techniques that reduce phytates.
Iron
Plant foods provide non-haeme iron, which is less bioavailable than haeme iron from animal foods. However, vitamin C dramatically enhances non-haeme iron absorption — consuming vitamin C-rich foods alongside iron-rich meals can increase absorption by 3-6 fold (Melina et al., 2016).
Vegans and vegetarians tend to have lower ferritin (iron stores) than omnivores, but rates of clinical iron deficiency anemia are not significantly higher in well-planned diets.
Calcium
Good vegan calcium sources include fortified plant milks and juices, calcium-set tofu, kale, bok choy, broccoli, tahini, and figs. Note that spinach and Swiss chard contain calcium but also oxalates that severely reduce absorption.
Selenium
Selenium content in plant foods depends heavily on soil selenium levels, which vary dramatically by region. Brazil nuts are exceptionally rich — a single nut can provide more than the daily requirement — but this varies by origin. People in selenium-poor regions (parts of Europe, China, New Zealand) may need to pay attention.
Key sources
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Melina V, Craig W, Levin S (2016). "Position of the Academy of Nutrition and Dietetics: Vegetarian Diets." J Acad Nutr Diet. 116(12):1970-1980.
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Burdge GC, Calder PC (2005). "Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults." Reprod Nutr Dev. 45(5):581-597.
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Leung AM, et al. (2011). "Iodine status and thyroid function of Boston-area vegetarians and vegans." J Clin Endocrinol Metab. 96(8):E1303-E1307.
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Tong TYN, et al. (2020). "Vegetarian and vegan diets and risks of total and site-specific fractures." BMC Med. 18:353.
Supporting Evidence
Sources:
- Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies (2017)
- Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets (2016)
- NIH Office of Dietary Supplements. NIH ODS vitamin B12, iodine, and vitamin D fact sheets
- NIH Office of Dietary Supplements. Dietary Supplement Fact Sheets
- Watanabe F, et al.. Vitamin B12 sources and bioavailability (2014)
- EFSA (European Food Safety Authority). Cyanocobalamin (vitamin B12) as a feed additive (2018)
- NIH Office of Dietary Supplements. Vitamin B12 - Fact Sheet for Health Professionals (2024)
EPIC-Oxford (Tong et al. 2020, BMC Medicine) followed 54,898 people for 17.6 years on average. Vegans had hip fracture HR 2.31 (95% CI 1.66-3.22) — about 15 extra hip fractures per 1,000 people over 10 years. The excess was attenuated when calcium and protein intakes were adequate and BMI was not low.
The Bottom Line
B12 supplementation is essential. Vitamin D3 supplementation is advisable for most people regardless of diet. Algal DHA/EPA is a reasonable precaution, especially during pregnancy. Everything else can usually be managed through informed food choices. A vegan diet does require more nutritional awareness than an omnivorous diet — this is honest and should be acknowledged, not dismissed. The flip side: omnivorous diets are associated with their own nutrient concerns (excessive saturated fat, sodium, haeme iron linked to colorectal cancer risk), and many omnivores are also deficient in vitamin D, fiber, and various micronutrients. No diet is automatically adequate without some degree of planning.
Practical Takeaways
Recommendation: Most adults benefit from 1,000-2,000 IU of vitamin D3 daily, regardless of diet. Get tested if uncertain. This is not a vegan-specific problem — it is a modern-indoor-lifestyle problem.
Recommendation: Consider 250-500 mg of combined EPA/DHA from algal oil daily, particularly during pregnancy and breastfeeding. Algal oil is the original source — fish accumulate DHA by eating algae (or eating fish that ate algae).
Recommendation: Use iodised salt regularly or take a supplement providing 150 mcg of iodine daily. Be cautious with kelp supplements, which can provide excessive amounts.
Recommendation: Emphasize zinc-rich foods (pumpkin seeds, lentils, chickpeas, cashews, hemp seeds) and use soaking and sprouting techniques. Supplementation is not routinely required but may be warranted if symptoms of marginal deficiency appear (slow wound healing, frequent infections, impaired taste).
Recommendation: Routine iron supplementation is NOT recommended for vegans. Instead, pair iron-rich foods (lentils, spinach, tofu, fortified cereals) with vitamin C sources, and avoid consuming tea or coffee with iron-rich meals (tannins inhibit absorption). Get ferritin tested annually, especially for menstruating individuals.
Recommendation: Aim for 700-1,000 mg of calcium daily through fortified foods and low-oxalate greens. Supplementation may be helpful if dietary intake is consistently low, but whole-food sources are preferred.
Recommendation: 1-2 Brazil nuts daily provides adequate selenium for most people. Alternatively, a multivitamin providing 55-70 mcg covers the RDA.
Sources & Evidence
9 sources cited across 3 claims
The plant-based omega-3 ALA (found in flaxseed, chia, walnuts, and hemp) converts to...
ObservationalAll diets benefit from nutritional planning
Expert ConsensusVegan hip fracture risk mitigated by calcium, protein, BMI
Cohort Study