The Vegan Supplement Guide: The Five Nutrients Plant-Based Eaters Actually Need

You've gone vegan, or you're seriously considering it. Maybe for ethical reasons, maybe for health, maybe because the climate maths finally clicked. The first thing well-meaning relatives ask is "but what about your B12?" — usually before "are you eating enough vegetables?". They're not entirely wrong: a plant-based diet covers most nutritional needs well, but a small handful of nutrients need real attention. Here's the honest list.

A varied plant-based diet — whole grains, legumes, nuts, seeds, vegetables, fruit, with optional fortified foods — meets or exceeds requirements for fibre, folate, vitamin C, magnesium, potassium, antioxidants, and many B vitamins. The British Dietetic Association's position is that well-planned vegan diets are appropriate for all life stages. The "well-planned" part is doing real work in that sentence.

1. Vitamin B12 — non-negotiable

B12 is the only nutrient that genuinely requires supplementation on a fully plant-based diet. It's made by bacteria, not plants, and reliable sources outside animal products are limited to fortified foods (some plant milks, nutritional yeast, breakfast cereals) or supplements. Vitamin B12 contributes to the normal functioning of the nervous system.

The NHS advises vegans to get B12 from fortified foods or a supplement.

2. Vitamin D — needed by everyone in the UK

This isn't a vegan-specific issue — Public Health England recommends supplementation for the entire UK population during October–March because of low sunlight angle. Target: 10 micrograms a day in autumn and winter (NHS).

3. Omega-3 (specifically EPA and DHA)

Plant sources of omega-3 (flaxseed, chia, walnut) provide ALA. The body converts ALA to EPA and DHA but inefficiently — typically 5–10% conversion to EPA, lower for DHA. Algal oil supplements provide EPA and DHA directly from the same source fish get them from (microalgae), with no fish required.

EPA and DHA contribute to the normal function of the heart (250 mg a day). Our Omega 3-6-9 Multi gives 95 mg per capsule and is not vegan.

4. Iron — especially for women

Plants contain plenty of iron, but it's non-haem iron, which is absorbed less efficiently than the haem iron from animal products. Vitamin C increases iron absorption.

If you're a menstruating woman, vegetarian or vegan, get your ferritin checked annually. It's a cheap blood test and the results will tell you whether dietary changes are enough or whether short-term supplementation is needed (under GP guidance).

5. Iodine

This is the quietly missed one. Iodine in the British diet comes mostly from dairy and white fish. Without those, below the UK reference intake of 140 micrograms a day. Plant sources of iodine include seaweed (variable, sometimes too high), iodised salt (rare in the UK compared to mainland Europe and the US), and fortified plant milks. A multivitamin with iodine adds to intake; check the amount on the label.

• Protein: easy to meet on a varied vegan diet (legumes, tofu, tempeh, seitan, nuts, seeds, whole grains).
• Calcium: dark leafy greens (kale, bok choy), tahini, almonds, fortified plant milks. Most fortified plant milks now match dairy's calcium per litre.
• Zinc: covered by pumpkin seeds, lentils, chickpeas, cashews. Soaking legumes and grains improves absorption by reducing phytates.

These are nutritious additions, not B12 replacements. Some spirulina products claim to provide B12, but the form is largely pseudo-B12 (analogues that the body can't use). Spirulina is not a reliable B12 source.

• A multivitamin with B12, D3 and iodine (check the vegan mark on the label).
• An algal omega-3 (EPA+DHA) capsule.
• Optional: separate iron, only if your ferritin levels indicate it.

A well-planned vegan diet is genuinely complete with five small additions: B12 always, D3 in winter (or year-round), algal omega-3, attention to iron, and iodine. Cover those and you're not playing nutritional catch-up — you're eating a diet that does well on its own metrics.