Vegan or vegetarian: what are the nutritional differences?

The difference comes down to four categories of food: eggs, dairy, honey and animal-derived processing aids. Vegetarians keep some or all of them, vegans drop all four. Nutritionally, that boundary matters less than most people assume for the majority of nutrients, but it moves three files decisively: vitamin B12, calcium and iodine.

The short version: according to the Swiss Federal Food Safety and Veterinary Office (FSVO), a well-balanced ovo-lacto-vegetarian diet supplies a healthy adult with enough iron, zinc, calcium and B vitamins without special supplementation, whereas a vegan diet requires B12 supplementation and a considerably higher level of nutritional knowledge applied consistently. That is not a stylistic nuance. It is the practical conclusion of the whole subject.

What the labelling rules actually say

A lot of discussions go nowhere because everyone uses a private definition. Swiss food law sets out labelling conditions, and the Swiss Federal Commission for Nutrition (FCN) reproduces them directly in its report for the FSVO. A product may be labelled:

  • “vegetarian” or “ovo-lacto-vegetarian” if it contains neither ingredients nor processing aids of animal origin, with the exception of milk and milk components such as lactose, eggs and egg components, or honey;
  • “ovo-vegetarian” if the only exceptions are eggs, egg components or honey;
  • “lacto-vegetarian” if the only exceptions are milk, milk components or honey;
  • “vegan” if it contains no ingredients of animal origin at all.

The phrase that does the heavy lifting is “processing aids”. An aid does not appear on the ingredient list because it is not present in the finished product, but it was used to make it. Animal rennet in cheese, fish gelatine used to fine certain wines, bone char in some sugar refining: those are aids. A “vegetarian” claim covers them. The absence of a claim tells you nothing either way. That is why label reading remains useful even in aisles you think you know, and our guide on how to read a food label as a vegetarian works through the edge cases.

The FCN also flags a methodological problem that explains a great deal of the contradiction in the literature: there is no standardised international classification, and most studies rely on self-reported answers using food frequency questionnaires originally designed for omnivorous populations. When two studies disagree, the first question is who was sorted into which box.

How many people this concerns in Switzerland

Figures circulate freely and contradict each other. The national menuCH survey, based on roughly 2,000 participants with data collected in 2014 and 2015, put the prevalence of veganism among Swiss adults at 0.38%. A study commissioned by Swissveg in 2016 arrived at 3%, plus or minus about 0.9 points. An eightfold gap is not measurement noise. It reflects how the question was asked and how participants were recruited. The FCN explicitly recommends follow-up studies with more specific questions on the reasons for and duration of the diet.

Keep the range rather than a single number, and treat any article announcing a dramatic surge by comparing two surveys that measured different things with appropriate suspicion.

Protein: the question is usually posed wrong

This is the most frequently asked question and also the one where the old teaching has aged badly. The idea that you must combine grains and legumes within a single meal to obtain a complete amino acid profile dates from the 1970s. The 2016 position of the Academy of Nutrition and Dietetics holds that appropriately planned vegetarian and vegan diets are nutritionally adequate at all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood and for athletes. What matters is variety across the day, not assembly within a plate.

In practice, if your week contains lentils, chickpeas, tofu or tempeh, wholegrains, nuts and seeds, the amino acid question resolves itself without arithmetic. Rice and beans remain a good culinary pairing rather than a meal-by-meal biochemical obligation. Our plant protein guide covers portions in detail.

Where the FCN does raise a genuine reservation is variability. The recent European studies it reviewed showed average macronutrient intakes in line with general recommendations, but with very high standard deviations. Put differently: the average is fine, a portion of individuals is not. And none of those studies attempted to identify the subgroups actually at risk. A vegan eating varied and sufficient food has no protein problem. A vegan living on bread, pasta and industrial substitutes may well have one, without the group average showing it.

For a vegetarian, eggs and dairy simplify the protein logistics, with a trade-off: they are also the main source of saturated fat on a vegetarian plate. The data reviewed by the FCN confirm that vegan diets are on average low in saturated fat and meet fibre recommendations.

Vitamin B12: the one real dividing line

This is where vegetarian and vegan stop being interchangeable.

Plants do not produce vitamin B12. The NHS and the FSVO agree: reliable sources are animal products and fortified foods. For vegans the FSVO is unambiguous and describes supplementation as necessary, whether in tablet form or through fortified products.

The point people routinely miss is that vegetarianism is not automatically safe. The FSVO notes that a lacto-vegetarian diet, meaning one without eggs, can result in a B12 intake below the recommendation, and that an ovo-vegetarian diet without dairy resembles the vegan profile as far as critical nutrients go. Someone eating three yoghurts a week and an occasional egg is not in the same position as a consistent ovo-lacto-vegetarian.

The most uncomfortable finding in the FCN report concerns practice rather than theory. Across most of the studies reviewed, only 50 to 70% of vegan participants were actually taking B12 supplementation, even though it is essential. So the problem is not that a vegan diet cannot be balanced. It is that a substantial share of the people concerned are not doing the one thing that is clearly recommended.

Watch out for false sources too. Seaweed, spirulina, tempeh, sauerkraut and mushrooms have long been presented as B12 sources. The FCN specifically notes that more nutritional data is needed on B12 content in fermented products. In practice you do not build B12 status on foods with uncertain content, much of which consists of inactive analogues. Nutritional yeast is a different case because it is frequently fortified and the label says so. See our piece on nutritional yeast and the dossier on vitamin B12 needs and reliable sources.

An established deficiency can cause anaemia and neurological damage that does not always fully reverse. Blood testing and what to do about the result belong to a doctor, not an article.

Calcium and bone health: do not skim this section

For a vegetarian eating dairy, calcium is rarely a difficulty. For a vegan it is a serious item on the checklist, and recent data have changed the tone of the discussion.

The prospective EPIC-Oxford study followed close to 55,000 people for an average of 17.6 years and published fracture risks by diet group in 2020. After adjusting for socio-economic factors, lifestyle confounders and body mass index, the risk of hip fracture was higher in fish eaters (hazard ratio 1.26), vegetarians (1.25) and especially vegans (2.31). In absolute terms that corresponds to roughly 2.9 additional cases per 1,000 people over ten years for vegetarians and 14.9 for vegans. Vegans also showed higher risks of total fractures and leg fractures.

Those figures need reading properly. This is an observational study: it establishes association, not causation, and the authors themselves conclude that bone health in vegans requires further research. The associations were slightly attenuated after additional adjustment for dietary calcium and total protein, which points at intakes rather than at the principle of the diet.

The FCN report adds a directly actionable detail drawn from the same cohort: the excess fracture risk was not present in vegans consuming more than 525 mg of calcium per day. That is not a recommended intake, which is higher, but a threshold below which the signal becomes clear. Reason enough not to leave calcium to chance.

Usable plant sources include calcium-set tofu, fortified plant drinks, green vegetables such as broccoli, cabbage and kale, sesame seeds and tahini, and dried fruit. The NHS points out a specific trap: spinach does contain high levels of calcium, but the body cannot digest much of it because of the oxalate content. Relying on spinach for calcium is a classic mistake. Our article on calcium without dairy sets out realistic portions.

Vitamin D belongs to the same bone equation. The NHS recommends that everyone consider a daily supplement during autumn and winter, vegetarian or not, because skin synthesis is insufficient at those times of year at our latitudes.

Iron: two forms, and a question of timing

Iron from plants, known as non-haem iron, is absorbed less efficiently than the haem iron in meat. This applies to vegetarians as much as to vegans, since the iron in eggs and vegetables is also non-haem. The NHS states that vegetarians are more likely to have lower iron stores than meat eaters.

Two practical levers are documented by the NHS. The first is pairing a source of vitamin C with an iron-containing meal: lemon over lentils, raw peppers in a chickpea salad, fruit for dessert. The second is less well known and routinely ignored: avoid tea and coffee during or immediately after main meals, since tannins and polyphenols reduce absorption. Shifting the coffee by an hour costs nothing and genuinely changes the outcome. See optimising plant iron absorption.

Soaking and sprouting legumes reduces phytate content, which otherwise hinders mineral absorption. The FCN notes that more research would be useful on how processing and cooking affect phytate content in foods, which is a good reason to present these techniques as helpful rather than decisive.

Iodine: a Swiss problem, not just a vegan one

Iodine is the most underestimated nutrient in this whole subject. The FCN recommends monitoring intake of nutrients that are critical not only in the vegan population but in the Swiss population generally, and names iodine and selenium specifically. In other words this is not a problem created by vegetarianism. It is a national one that removing fish and dairy can worsen.

The data reviewed by the FCN indicate that the risk of iodine shortfall is higher among vegans than in other dietary patterns. The NHS places iodine on the list of nutrients for which vegans should use fortified foods or consider supplements, alongside vitamin D, vitamin B12, selenium and calcium.

Iodised salt remains the simplest lever, provided you check that your salt actually is iodised. Non-iodised, coarse and speciality salts have spread widely, and plenty of people have quietly stopped being covered. Seaweed is a source of iodine but comes with a serious flaw: content is highly variable and can be extremely high, particularly in kombu, to the point of disturbing thyroid function. It is not a food to eat daily without thinking. Our article on avoiding iodine deficiency without fish gives the orders of magnitude.

Zinc, selenium and omega-3

Zinc is found in legumes, nuts, seeds and wholegrains. Those same foods contain phytates, which reduce bioavailability, hence the value of soaking and fermenting. Zinc is among the nutrients the FSVO lists as potentially insufficient in an unplanned vegan diet. See vegetarian zinc sources.

For omega-3 the situation is identical for vegetarians and vegans, since neither eats fish. Ground flaxseed, chia seeds, walnuts and rapeseed oil supply alpha-linolenic acid (ALA). The body converts it into EPA and DHA, but at a low and variable rate. The NHS is cautious and writes that evidence suggests vegetarian sources of omega-3 may not have the same benefits for reducing heart disease risk as those in oily fish. Microalgae supplements provide EPA and DHA directly and are a reasonable option, particularly during pregnancy and breastfeeding. See omega-3 from nuts, seeds and algae and choosing algae-based omega-3 supplements.

What the health studies actually show

This is the part where the temptation to conclude too quickly should be resisted in both directions.

EPIC-Oxford followed 48,188 people with no history of cardiovascular disease for 18.1 years. The 2019 result: after adjustment, vegetarians including vegans had a 22% lower rate of ischaemic heart disease than meat eaters, equivalent to about 10 fewer cases per 1,000 people over ten years. The benefit was partly attenuated after adjustment for self-reported high cholesterol, high blood pressure, diabetes and body mass index, suggesting it operates largely through those factors.

The same study found a 20% higher rate of total stroke among vegetarians, equivalent to about 3 additional cases per 1,000 people over ten years, mostly haemorrhagic. That association did not attenuate after adjustment for disease risk factors. The mechanism is not established. It is an uncomfortable finding, it is real, and it rarely appears in articles presenting vegetarianism as purely protective.

The FCN, for its part, concludes that the most recent European studies do not show clearly positive long-term effects of a vegan diet on non-communicable diseases, and that given the small number of vegan studies and the divergent findings, further research is needed before a vegan diet is recommended as a health measure in Switzerland.

That caution does not invalidate the Academy of Nutrition and Dietetics position, which remains that appropriately planned versions of these diets are adequate and associated with reduced risk for several conditions. The two texts are compatible: a well-constructed diet is fine, and that is not the same thing as a public health recommendation.

The “plant-based equals healthy” shortcut

Here the FCN makes the single most useful observation in its report, and it contradicts a widespread assumption. Where data on fruit and vegetable consumption were available, the recommendation of roughly three vegetable and two fruit portions was met on average, but with very large variability. The commission’s conclusion is blunt: it is not demonstrated that a vegan diet can always be associated with a diet rich in fruit and vegetables, so it can hardly be assumed that a vegan diet automatically benefits from the advantages of such a diet. The FCN notes that this assumption is nonetheless one of the axioms of most position papers on the subject.

Removing animal products does not fill the plate with vegetables by itself. A diet of white bread, pasta, crisps, sugary drinks and industrial substitutes is perfectly vegan and perfectly unbalanced. A 2019 review on plant-based diets and cardiovascular prevention reaches the same conclusion: plant-based patterns high in wholegrains, fruit, vegetables, nuts and legumes are associated with lower cardiovascular risk, while those built on refined grains, potatoes and fries, and foods high in added sugar are linked to increased risk.

The quality of the plant foods matters as much as the exclusion of the animal ones. That holds for vegetarians and vegans alike.

Adapting to specific situations

General recommendations stop where particular situations begin.

Pregnancy and breastfeeding. The NHS stresses the need to secure vitamin and mineral intake for the child to develop healthily. B12 supplementation becomes non-negotiable, and a DHA source is worth discussing. Medical follow-up is the rule rather than an option.

Infants and young children. The FSVO published a specialist communication in February 2026 on counselling tools for vegetarian and vegan nutrition in small children, which signals that the topic is treated as sensitive. A vegan diet for a young child is built with a paediatrician and a recognised dietitian, never alone.

Older adults. Protein needs rise with age while appetite often falls. A restrictive diet combined with insufficient intake is a genuine risk, including for bone health given the data above.

Endurance athletes. The food volume required is high, and plant-based diets are bulky and fibre-rich, which can become limiting. The issue is mostly energetic. See a veggie menu for endurance athletes.

People with a history of disordered eating. The FCN report devotes a section to eating disorders. In some individuals a restrictive pattern can serve as a socially acceptable vehicle for restriction. This is not a general rule but an individual point of vigilance.

Ten common mistakes

  1. Assuming a vegetarian diet rules out B12 deficiency, when the egg-free version can fall below recommendations.
  2. Relying on seaweed, spirulina or tempeh as B12 sources.
  3. Counting on spinach for calcium, when oxalates block much of the absorption.
  4. Going vegan without ever checking calcium intake, given the 525 mg per day threshold from EPIC-Oxford.
  5. Drinking tea or coffee immediately after an iron-rich meal.
  6. Replacing iodised salt with a non-iodised speciality salt without compensating elsewhere.
  7. Eating kombu regularly, with a real risk of iodine excess.
  8. Treating ALA from flax and walnuts as equivalent to EPA and DHA.
  9. Swapping meat for industrial substitutes without checking salt and fat.
  10. Reading a single study and drawing a general conclusion, when the findings diverge between outcomes within the same cohort.

Common questions

Do grains and legumes have to be combined in the same meal? No. Variety across the day is enough, in line with the 2016 Academy of Nutrition and Dietetics position.

Should a vegetarian supplement B12? It depends which version. An ovo-lacto-vegetarian eating eggs and dairy regularly generally meets requirements according to the FSVO. A lacto-vegetarian without eggs can fall below them. A blood test settles it, not an estimate.

Is a vegan diet better for the heart? EPIC-Oxford found 22% less ischaemic heart disease among vegetarians, but also 20% more stroke, mostly haemorrhagic. The FCN considers the long-term effects not clearly positive and calls for more research.

Are vegans at higher risk of fractures? In EPIC-Oxford, yes, with hip fracture risk 2.31 times that of meat eaters. The association was attenuated after adjusting for calcium and protein, and absent above 525 mg of calcium per day. It is an association, not a fate.

How many vegans are there in Switzerland? Between 0.38% according to menuCH and around 3% according to a Swissveg survey. The gap is methodological.

Does honey change anything nutritionally? No, its nutrient contribution is negligible. Its presence is a matter of ethical definition and labelling rather than dietary balance.

Deciding in practice

If you are already vegetarian and considering going vegan, the list of things to put in place is short and well known: a B12 supplement taken consistently, a daily calcium source that is identified rather than theoretical, iodised salt or an equivalent iodine source, a decision about vitamin D over winter, and an EPA and DHA source if you are pregnant, breastfeeding or have a specific risk factor. Variety handles the rest.

If you are simply reducing animal products without targeting a category, the same logic applies more loosely. Our article on the gentle vegetarian transition sets out the steps.

What separates a diet that holds up from one that drifts is not the label attached to it. It is whether legumes, wholegrains, vegetables, fruit, nuts and seeds are actually on the plate, and whether the handful of nutrients your chosen version makes harder to obtain are being managed explicitly rather than hopefully.

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