A well-planned vegan diet covers most of what your body needs, but a handful of nutrients are genuinely harder to get from plants alone. This guide walks through the ones worth prioritising, what the science actually says, and how to choose supplements that are honest about their doses.
Key takeaways
- Vitamin B12 is non-negotiable. It is not reliably found in plant foods, and B12 contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue.
- Vitamin D matters in a UK winter. Everyone in Britain is advised to consider a supplement from October to March, and vitamin D contributes to the normal function of the immune system.
- Iodine is easy to overlook. Dairy and fish are common sources, so plant-based eaters need another route. Iodine contributes to normal thyroid function.
- Iron and omega-3 deserve attention. Plant iron is absorbed less efficiently, and long-chain omega-3 comes mainly from algae for vegans.
- Dose transparency beats marketing. Look for clear amounts per serving, third-party testing and vegan formulation rather than long, vague ingredient lists.
Why some nutrients run low on a vegan diet
Cutting out meat, fish, eggs and dairy removes several concentrated sources of specific nutrients at once. That does not make a plant-based diet deficient by default, but it does shift where your intake comes from. Some nutrients simply are not present in plants in useful amounts, others are present in a form your body absorbs less readily. The sensible approach is not to supplement everything, it is to identify the genuine gaps and cover those well.
The list that follows is ordered roughly by how commonly it needs attention for people eating entirely plant-based in the UK. Your own needs depend on your diet, your sunlight exposure, your life stage and any conditions you manage, so treat this as a starting map rather than a prescription. If you want the broader picture, our roundup of the best vegan supplements in the UK for 2026 sits alongside this guide.
The priority nutrients to get right
These are the six that come up most often when dietitians look at plant-based diets. For each, we have noted what it does using the approved nutrient wording, and where a Healthier Options product happens to contribute.
Vitamin B12
This is the one nutrient almost every vegan needs to supplement. B12 is produced by bacteria, not plants, so reliable dietary sources for plant-based eaters are fortified foods and supplements. It is worth taking seriously because vitamin B12 contributes to normal energy-yielding metabolism, to the reduction of tiredness and fatigue, and to the normal function of the immune system. Both regular smaller daily doses and larger less frequent doses can work, since absorption changes with the amount taken.
Vitamin D
Between October and March, sunlight in the UK is too weak for the skin to make much vitamin D, which is why national guidance suggests everyone consider a supplement over winter. Vitamin D contributes to the normal function of the immune system and to the maintenance of normal bones and normal muscle function. The vegan-friendly form to look for is D3 derived from lichen rather than sheep's wool. Our Super Greens Gummies include 2,000 IU of vitamin D3 per daily serving, which is 1000% of the NRV.
Iodine
Iodine often slips under the radar because two of its main dietary sources, dairy and white fish, are exactly the foods a vegan diet leaves out. Iodine contributes to normal thyroid function, normal energy-yielding metabolism and normal cognitive function. Sea vegetables are a plant source, though their iodine content varies a lot, so consistency and moderation both matter. Our Sea Moss with Bladderwrack and Burdock Gummies use Irish sea moss and bladderwrack as a natural source of iodine. If you want to go deeper here, we have a fuller piece on vegan iodine sources in the UK.
Iron
Plant foods do contain iron, but in the non-haem form, which the body absorbs less efficiently than the iron in meat. Beans, lentils, tofu, wholegrains and dark leafy greens all contribute, and pairing them with a source of vitamin C at the same meal helps absorption. Tea and coffee with meals can reduce it. Iron supplements can be useful, though they are worth taking on the basis of a blood test rather than guesswork, because more is not better here.
Omega-3 (EPA and DHA)
Flax, chia and walnuts provide ALA, a short-chain omega-3, but the body converts only a small fraction of it into the longer-chain EPA and DHA found in oily fish. For plant-based eaters who want a direct source, algae oil supplies EPA and DHA without the fish. This is one where a targeted supplement often makes more sense than relying on conversion from seeds alone.
Magnesium and zinc
These two are usually adequate on a varied plant-based diet, but they can run lean for some people. Magnesium contributes to a reduction of tiredness and fatigue, to normal energy-yielding metabolism, to normal psychological function, to the normal functioning of the nervous system and to normal muscle function. Zinc absorption can be lower from plant foods because of phytates in grains and legumes, so variety and preparation methods like soaking help. Our Super Greens Gummies include 120 mg of magnesium glycinate per serving.
What to actually look for in a supplement
Once you know which nutrients you are targeting, the label is where good products separate themselves from filler. A few things reliably signal quality.
- Named doses per serving. You should be able to see exactly how much of each active ingredient you get, in milligrams or micrograms, not just a proprietary blend total.
- The right form. Vitamin D3 from lichen for vegans, magnesium in a well-absorbed form like glycinate, and B12 as methylcobalamin or cyanocobalamin all matter more than the raw number.
- Third-party testing. Independent lab checks confirm what is in the bottle matches the label and screen for contaminants. All Healthier Options gummies are third-party tested and made in the UK.
- Genuine vegan formulation. Watch for gelatin in soft gels and lanolin-derived vitamin D. Pectin-based gummies avoid the gelatin problem entirely.
- Honest scope. No single product covers every nutrient at a meaningful dose. Be wary of anything claiming to do everything at once.
Do you need a greens powder or a multivitamin too?
Greens products and multivitamins can be convenient, but they play different roles. A multivitamin spreads modest amounts of many nutrients across one dose, which can be a reasonable insurance policy. A greens formula leans on whole-food plant ingredients like moringa and spirulina plus added vitamins. Neither replaces a targeted B12 or vitamin D supplement if those are your real gaps. We compare the two approaches in more detail in our piece on super greens gummies versus multivitamins, which is worth a read before you buy either.
Our own Super Greens Gummies sit in the greens category, combining moringa, spirulina and saffron with L-theanine, magnesium glycinate and vitamin D3. You can see the full plant-based range on our vegan supplements collection.
A simple way to prioritise
If you want a practical order of operations, start with vitamin B12 because it is the clearest gap. Add vitamin D through the darker months, and think about iodine if your diet has no consistent source. Consider algae-based omega-3 next, and only add iron after a blood test suggests you need it. Magnesium and zinc come last for most people, worth topping up only if your diet or symptoms point that way. Building the habit matters as much as the ingredients, so a routine you will actually keep beats a perfect stack you abandon.
Whatever you choose, speak to your GP before starting if you are pregnant, breastfeeding, taking medication or managing a health condition, particularly with anything affecting iron or thyroid function.
Common questions
What is the one supplement every vegan should take?
Vitamin B12 is the strongest candidate. It is not reliably available from plant foods, and it contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue. Most people on a fully plant-based diet supplement it in some form.
Can I get enough iodine from sea moss?
Sea moss and other sea vegetables are a natural source of iodine, and iodine contributes to normal thyroid function. The catch is that iodine levels in sea vegetables vary, so consistency and moderation both matter. Do not stack multiple high-iodine products at once.
Do vegan gummies work as well as capsules?
What matters is the dose and the form of each nutrient, not the delivery format. Pectin-based gummies can carry meaningful amounts of vitamins and minerals while being easier to take consistently. Check the per-serving amounts on the label just as you would with a capsule.
Is a multivitamin enough on its own?
A multivitamin can help cover small gaps, but it will not always provide enough vitamin B12 or vitamin D at the levels a plant-based diet needs. Read the label and top up the specific nutrients that fall short rather than assuming one product does it all.
