Nutrients for Vegans: Keeping an Eye on the Critical Micronutrients

The short answer first: A vegan diet covers almost everything – with one clear exception. You have to supplement vitamin B12; there is no way around it. In addition, it pays to keep a watchful eye on iron, zinc, iodine, the omega-3 fatty acids DHA and EPA, calcium, vitamin D and selenium. Anyone who knows these eight points and plans cleverly is excellently supplied on a purely plant-based diet.

Imagine you have just switched to vegan: the fridge is full of legumes, oats, nuts and colourful vegetables. The good news is that this foundation is astonishingly rich in nutrients. The honest news is that some micronutrients occur almost exclusively in animal foods or are absorbed less well from plants. This article is precisely about these gaps – and how you can close them with confidence.

Why individual nutrients are critical on a vegan diet

"Critical" does not mean "dangerous", but simply: here you need to look more consciously than with a mixed diet. The reason lies in the origin. Some nutrients are predominantly accumulated by animals in nature (B12 above all), while others are present in plants in a form that your gut absorbs less well – for example the non-haem iron from lentils or the zinc from wholegrain that is held back by phytates. Your body is clever, but it cannot outwit chemistry. That is why the rule is: variety on your plate plus targeted supplementation where it is needed.

Vitamin B12 – the only true must

Vitamin B12 occurs in a usable form practically only in animal foods. On a purely plant-based diet, supplementation is therefore not optional but necessary – this is scientific consensus, not a fringe topic. B12 contributes to normal energy-yielding metabolism, to the normal function of the nervous system, to normal psychological function and to normal formation of red blood cells. It is involved in cell division and in the breakdown of homocysteine – in short, in processes you do not want to leave to chance.

A persistent myth surrounds algae: spirulina, chlorella and the like are not a reliable source of B12. They mainly contain so-called pseudo-B12, which your cells cannot use and which can even distort test results. Here you should rely on a genuine B12 supplement – as methylcobalamin, cyanocobalamin or a combined form. Which form suits whom and when to take it can be read in the guide Covering vitamin B12 on a vegan diet and under B12 forms: methylcobalamin & co.

Iron: the amount is right, absorption is the lever

Iron is plentiful in legumes, rolled oats, pumpkin seeds and green vegetables. The catch: plant-based non-haem iron is absorbed less well than the haem iron from meat. The elegant trick is vitamin C: a glass of orange juice, strips of bell pepper or a squeeze of lemon with your meal noticeably raises iron absorption. Conversely, coffee and black tea slow it down when taken directly with food – here a gap of about an hour helps. Iron contributes to normal formation of red blood cells, to normal oxygen transport and to the reduction of tiredness and fatigue. More in the guide Recognising & preventing iron deficiency and on the combined duo under Combining vitamin C and iron.

Zinc and iodine: the quiet two

Zinc is found in wholegrain, pumpkin seeds, lentils and nuts – but phytates in plant-based food reduce its availability. Soaking, sprouting and sourdough fermentation partly break down this brake. Zinc contributes to the normal function of the immune system, to the protection of cells from oxidative stress and to the maintenance of normal skin, hair and nails. Details in the zinc guide.

Iodine is often in short supply on a vegan diet because milk and fish, the main sources, are dropped. Iodised table salt is the simplest safeguard; sea algae do provide iodine, but their content varies enormously and they can quickly lead to overdosing – better to be cautious here. Iodine contributes to normal thyroid function and to normal cognitive function. More under Iodine: effect, requirement, thyroid.

Omega-3: algae oil beats the detour

The plant-based omega-3 fatty acid ALA from linseed oil, walnuts and chia is valuable – but your body only converts it to a limited extent into the long-chain DHA and EPA. The direct vegan solution is algae oil, the original source from which fish also obtain their DHA and EPA. So you simply skip the fish as the middleman. DHA contributes to the maintenance of normal brain function and normal vision at an intake of 250 mg per day. More under Covering omega-3 on a vegan diet with algae oil and in the comparison Fish oil vs. algae oil.

Calcium, vitamin D and selenium

Calcium is provided by green vegetables (kale, broccoli), sesame, almonds, tofu and fortified plant drinks. Calcium contributes to the maintenance of normal bones and teeth. Vitamin D is produced by the body through sunlight on the skin – in winter the position of the sun in our latitudes is not sufficient for this, so that supplementation becomes sensible for many. Vegan D3 is available from lichen; see Vitamin D3 + K2 and Vitamin D: dosage, blood level, winter. Selenium is often scarce in European soils; Brazil nuts are a well-known source (but enjoy them in measured amounts). Selenium contributes to normal thyroid function and to the protection of cells from oxidative stress.

In practice: how to plan your supply concretely

All theory is grey – so let us look at implementation. With B12 you have two options: a small daily dose or a higher dose once or twice a week (the body absorbs proportionally less from larger amounts, but compensates for this through the quantity). Look for a supplement with a clearly declared form and dose. With vitamin D, supplementation is worthwhile for many during the winter half of the year; the appropriate amount is ideally guided by your blood level, see which vitamin D supplement to buy. With omega-3 the target figure is tangible: 250 mg DHA (plus EPA where possible) per day – an algae oil with a declared DHA/EPA content makes this easy to track, more under Omega-3: how much per day.

With the minerals, above all the clever combination on your plate counts: iron plus a vitamin C source, zinc from soaked or sprouted legumes, iodine reliably via iodised salt. Anyone using a supplement should look for well-tolerated, well-absorbed forms – such as bisglycinates for iron and zinc. How best to space supplements over time is shown in Nutrients: before or after eating and the order when taking many supplements.

For whom it particularly pays to look

Some life situations increase the requirement or the risk of gaps. During pregnancy and breastfeeding, the demands on several nutrients rise significantly – here planning absolutely belongs under medical supervision, see Nutrients for a desire to have children and during pregnancy. Endurance athletes often have a higher iron turnover; women regularly lose iron through menstruation. And anyone who exercises a lot or is older should keep an eye on their protein and B12 supply. The principle remains the same: first check, then supplement in a targeted way.

What research is investigating

There is a great deal of research around plant-based nutrition. Well-documented textbook knowledge is the role of the mentioned nutrients as essential building blocks – such as iron in haemoglobin or B12 in homocysteine metabolism. Actively under investigation is how much the conversion of ALA to DHA/EPA differs between individuals, what role the gut microbiome plays in nutrient absorption and how fermentation affects the bioavailability of zinc and iron. Fascinating but not yet conclusively settled are questions about the optimal B12 form and dose as well as the individual conversion rate of plant-based fatty acids. What can already be said: a well-planned vegan diet plus B12 is regarded by professional societies as complete for every stage of life – from childhood to old age, provided the critical points are observed.

An honest classification

It is certain that B12 must be supplemented, full stop. Equally well documented are the authorised functions of the individual vitamins and minerals. Less clear-cut is exactly who should additionally supplement – this depends on your choice of foods, your sunlight and your blood values. The most reliable compass is therefore not a blanket supplement package but a blood test at your doctor's. After that you supplement in a targeted way rather than on suspicion.

Overview: the critical nutrients at a glance

Matching products from Scheunengut

For the critical nutrients you will find matching categories with us – lab-tested and made in Germany:

• B vitamins including B12 – your must-have.
• Iron, zinc, iodine, selenium, calcium and vitamin D as single-nutrient supplements.
• As a practical basic safeguard, the category multivitamin and vitamins, minerals & trace elements.

Further reading: Nutrients for vegetarians, Difference between vegetarians and vegans and recognising vegan supplements.

Frequently asked questions (FAQ)

As a vegan, do I really have to supplement B12?

Yes. Vitamin B12 occurs in a usable form practically only in animal foods, which is why supplementation is necessary on a purely plant-based diet – this is scientific consensus. Algae such as spirulina or chlorella are not a reliable source, as they mainly contain ineffective pseudo-B12. Use a genuine B12 supplement.

Is linseed oil enough as a vegan omega-3 source?

Linseed oil provides the precursor ALA, which the body only converts to a limited extent into the long-chain DHA and EPA. For a direct supply of DHA and EPA, algae oil is the vegan solution – it is the original source from which fish also obtain their omega-3. 250 mg DHA per day contributes to the maintenance of normal brain function.

Which nutrients should I have checked in my blood as a vegan?

A sensible compass is a blood test that covers above all B12 (ideally holo-transcobalamin), ferritin (iron stores) and vitamin D. Depending on your diet, it is also worth looking at zinc, iodine and the omega-3 index. That way you supplement in a targeted way rather than on suspicion. It is best to discuss the results with your doctor.

Are spirulina and chlorella still worthwhile?

As a green nutrient supplement with protein, chlorophyll and minerals they can be an enrichment. Only as a B12 source are they no good, because they mainly contain ineffective pseudo-B12. So feel free to use them as an addition, but rely on a genuine supplement for B12.