Well-planned vegan and vegetarian diets are associated with significant health benefits — including lower rates of cardiovascular disease, Type 2 diabetes, obesity, and certain cancers. However, “well-planned” is the operative term. Several nutrients are either absent from or poorly bioavailable in plant-based diets and require deliberate attention or supplementation. This guide covers the predictable gaps and practical solutions.

Vitamin B12: The Non-Negotiable

B12 is found exclusively in animal products. There are no reliable plant sources (spirulina and fermented foods have been proposed but their B12 analogues are not bioavailable). All vegans must supplement. The UK Vegan Society recommends daily supplementation at 10mcg or higher, or 2000mcg twice weekly. This is one of the few nutritional recommendations with complete consensus. Vegetarians who consume dairy and eggs have lower risk but should still monitor levels, particularly after 50.

Vitamin D

While Vitamin D deficiency is nearly universal in the UK population (see our full guide), vegans face an additional consideration: the most common supplemental form is D3 derived from lanolin (sheep’s wool) — not vegan. Vegan D3 derived from lichen is now widely available and equally effective. D2 is vegan but approximately 3× less effective at raising serum levels. Vegan D3 from lichen is the optimal choice.

Omega-3 DHA and EPA

As covered in our omega-3 guide, ALA from flaxseed and walnuts converts only inefficiently (~5–10%) to DHA and EPA. Algae-based omega-3 supplements provide direct DHA and EPA — the same bioavailable form found in fish — from the original marine source. This is essential for vegans and highly recommended for vegetarians, particularly during pregnancy and for cognitive health.

Iron

Non-haem iron (from plants) is 3–4× less bioavailable than haem iron (meat/fish). Vegans and vegetarians need approximately 1.8× the iron intake of meat-eaters. Key strategies: maximise non-haem iron sources (lentils, tofu, quinoa, fortified foods, dark greens), always combine with vitamin C, and avoid tea, coffee and calcium within 1–2 hours of meals. Regular ferritin monitoring (GP or private blood test) is sensible for vegans, particularly women.

Calcium

Without dairy, calcium must come from: calcium-set tofu (check the label — not all tofu is calcium-set), fortified plant milks (look for 120mg+/100ml), kale and pak choi (not spinach), almonds, sesame/tahini, chia seeds. If dietary calcium consistently falls below 700mg, supplementation with calcium citrate (absorbable without food) is appropriate.

Iodine

Iodine is significantly underrecognised as a vegan deficiency risk. Dairy is the primary iodine source in the UK diet — vegans and those avoiding dairy are at substantial risk of deficiency. Iodine is essential for thyroid hormone synthesis and particularly critical during pregnancy for fetal brain development. Seaweed provides iodine but in highly variable and sometimes excessive amounts. A vegan supplement containing 150mcg iodine daily is recommended.

Zinc and Selenium

Zinc bioavailability from plant sources is reduced by phytates (found in legumes, wholegrains, seeds). Soaking and fermenting foods reduces phytates. Selenium is very variable — UK soil is selenium-depleted and plant foods reflect this. 1–2 Brazil nuts daily provides adequate selenium without risk of excess. A small zinc supplement (10–15mg) may be worthwhile for vegans who don’t consume zinc-rich foods regularly.

Frequently Asked Questions

Browse vegan vitamins and supplements at Huncoat Pharmacy. Related: B12 Guide, Iron Deficiency, Vitamin D.

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