Why I’m not vegan: biological and philosophical arguments

Why I’m not vegan: biological and philosophical arguments

Becoming vegetarian or, “even better”, vegan, is the trend now in the health and fitness world. Does that mean it’s the best thing ever and we all need to do it? For me, neither my knowledge nor my beliefs allow me to do so.

There are lots of different types of vegans:

  • Some are tolerant, some aren’t. In fact, those of us who aren’t vegan can often feel pressured and think we need to justify ourselves.
  • Some of them know and admit the scientific data for and against their diet, some just know them but don’t admit them publicly, some of them don’t even know them.
  • Some of them are so because of their beliefs about animals, others for the environment, others for health, others for a mix of everything and others (too many) just for the trend and what they hear on social media.

I respect completely those who don’t consume animal products because their ethics tell them that’s intrinsically wrong. We should all be able to act with freedom of conscience. However, that’s the only case I consider really valid. The rest of arguments are quite weak, and in many cases they don’t even serve to defend veganism in its essence: rather, to support a more sustainable production, healthier lifestyle habits, better animal treatment, etc.

In this post, I’ll explain 5 reasons why I’ve decided not to be vegan: the life cycle; religion; the biological fact that human beings aren’t designed for veganism; health and ecology. I’ll also address the topic of animal wellbeing. And, finally, I’ll tell you the changes I’ve actually decided to make instead of becoming vegan.

Reason 1: Plants eat animals

The first argument has to do with the natural world and the way the life cycle works. All living beings are intertwined and our interrelationships are intimate and complex, so in fact we can’t establish firm boundaries. Eating plants is eating animals, and eating animals is eating plants. Why? Because plants feed on the nutrients they absorb from the soil, and that soil is made of rock particles and rests of plants and… animals. Thanks to the death and decomposition of animales, the plants that we can eat are able to grow.

Reason 2: Religion

Forgive me for expanding on this point, but I’ve read too much nonsense that I need to clarify it well. As I’ve said, I’d only consider not eating animals if I believed that was wrong in itself. And the reason I don’t is simple: it isn’t a belief compatible with Christianity. Multiple Bible examples prove it. Let’s see just some of them:

Old Testament

It’s true that the Genesis doesn’t say we ate meat in Paradise (God only gives explicitly to Adam and Eve the vegetables as food), although this doesn’t either mean a prohibition as some want to see. But in any case, this doesn’t say anything about the life of men after the original sin, which is a very different state, with other corporal needs.

In fact, shortly after that passage quoted by Christian vegans (Genesis 1:29) we find the story of Cain and Abel (Genesis 4:1-16). Cain was a “tiller of the ground” and offered God fruits of the ground; Abel was a “herder of flocks” and offered the fatty portion of the firstlings of his flock. God preferred the second offering. Obviously, this isn’t about the offering itself, but about the heart of each of them… But it also shows that God didn’t find anything wrong with Abel killing sheep.

«Sacrifice of Abel». Juan Antonio de Frías y Escalante. 1667-1668. ©Museo Nacional del Prado

Indeed, many Jewish feasts implied animal sacrifices. And that had been inspired by God Himself. Why, if God didn’t want us to eat meat for nourishment, would He command us to kill even more animals?

New Testament

But someone might think that’s only of the Old Covenant and the “new men” mustn’t do it anymore. However, the reality is that Jesus not only doesn’t condemn eating animals, but do so Himself several times in the Gospel, and also gives them to others to eat (as in the multiplication of loaves and fish). Even after the Resurrection, when He appears to His disciples, He asks them for fish to eat (John 21:5).

And that can’t be explained just by the context of that time. Jesus did many things that shocked the Jews, He could as well have established vegetarianism if that was God’s will. He wouldn’t have been the first one to promote a diet like that, either: in the Greek world (with which the Jews were familiar because of the Hellenization) we have the example of sages such as Pythagoras. In fact, Jesus did say something novel in regards to meat: that all of them were allowed, not as in the Old Law, where some of them were forbidden: “Thus he declared all foods clean” (Mark 7:19).

«Multiplication of the loaves and fish». Ambrosias Francken I. 16th century. Royal Museum of Fine Arts Antwerp

He even says to St. Peter, in a vision with four-legged animals, reptiles and birds: “Slaughter and eat” (Acts 10:12-16). The arguments of some vegans saying that Jesus called the fishermen to be His disciples so they stopped doing that job and thus killing fish, or that He expelled the merchants from the Temple not because they were doing business there but just because what they sold were animals… are therefore proven laughable.

This doesn’t mean a Christian has to eat meat or animal products if he doesn’t want to (in fact there are religious orders that are vegetarian)… only that he can’t consider it compulsory for everyone because of religious reasons.

Reason 3: Human beings aren’t designed for veganism

It’s just not natural. Another thing would be saying that in the current circumstances men can defy nature thanks to science. Again, that’s a personal choice. But what can’t be argued is that it’s by itself the best diet for men.

We don’t need but to look at our bodies and compare them with those of carnivore, omnivore and herbivore animals to realize that biologically we are the second. We don’t have carnivore teeth, say vegans correctly. We neither have the long digestive tract of herbivores. Which by the way is what allows us to have the brain thanks to which we can think about these dietary diatribes. “Brain expansion was possible because of the parallel reduction of the size of the digestive tract” (p. 16). Something impossible for an herbivore, that needs a very big one, since vegetables require a greater processing than meat. Moreover, this huge brain we got needs omega 3 fatty acids, but we didn’t develop in parallel a mechanism to produce those. Why? Because it wasn’t necessary: we had fish.

Comparison: human vs herbivore (rabbit) digestive tract

Diets around the world

We can as well check that there are no traditionally vegan cultures. Each people’s diet can vary a lot depending on its geographical location and its available resources, but none excludes animal foods completely. In the intertropical zone, plant-based diets are prevailing, such as the one of the Kitavans of Papua New Guinea —who also eat fish, mind you—, with exceptions such as the Masai; whereas as we ascend towards the Arctic, the consumption of animal products increases, being for example the basis —and practically the only kind of food— of diets of peoples such as the Inuit.

And that doesn’t mean ones are healthier than others. For example, if we compare the Tuoli of China with other nearby peoples that consume much less animal products (they’re an exception in the area), we observe there are no significant differences regarding mortality or incidence of illnesses. In some cases, they even come off better than their neighbors.


Furthermore, our body is much better equipped to absorb certain macro and micronutrients from animal products rather than vegetables. The most remarkable case is perhaps protein: the percentage of animal protein absorption is about 90%, whereas the one of vegetable protein is between 60 and 70%, due to the presence of limiting amino acids. What’s more, vegetable proteins are usually incomplete, that is, don’t have all the essential amino acids (the one the body can’t make on its own and needs to get through food). Of course, they have a lot of other advantages, and this problem can be solved with the right planning; I’m just trying to show how our organism works.


With regard to micronutrients, the same happens for example with iron, omega 3 fatty acids, and vitamins such as A, D, K2 and B12. All of which are absolutely fundamental for life. For example, vitamin B12 is essential to ensure the proper functioning of the nervous system, DNA synthesis and red blood cells making, among other things*. All vegans —I’m not generalizing, there are no exceptions here— need to take vitamin B12 supplements. Would our body really have, if it was made for veganism, such a grave requirement?

In the rest of the cases —although it’s unclear in some of them, like with omega 3 fatty acids—, normally we can get the right amounts with some maneuvers (for example, consuming foods with vitamin C together with others with iron in order to ease the absorption of the latter by neutralizing phytates). But again, they aren’t the organism’s preferred source to get elements that are however essential for it.

Reason 4: Health

Despite everything we’ve seen about the human body, there are a lot of people who insist that a vegan diet is the best one for our health. In order to do it, they usually turn to two strategies: praising the virtues of vegetable foods and demonizing animal foods. The first one is 100% corrects, but the fact that they’re good doesn’t mean they have to be the only ones.

The second one normally hides a manipulation: they say the possible counter-indications of animal products, all of them, even the smallest ones, even the ones that only apply to certain populations or to specific illnesses, even the ones that aren’t demonstrated by any serious study (counter-indications that, by the way, we also find in the vegetable world, although those ones are silenced). And the benefits for a moderate consumption of animal products aren’t mentioned, even if they meet all the opposite characteristics.

that only apply to certain populations or to specific illnesses. Even the ones that aren’t demonstrated by any serious study. Counter-indications that, by the way, we also find in the vegetable world, although those ones are silenced). And the benefits for a moderate consumption of animal products aren’t mentioned, even if they meet all the opposite characteristics.

THE healthy diet?

Of course there are people that become much healthier when they adopt a vegan diet. As it happens with every diet that implies paying more attention to what we eat. The basis of all diets that succeed in making people lead a healthier lifestyle doesn’t lie in the particularities of each one, but in what they share: prioritizing real food before ultra-processed, eating more veggies, learning about macro and micronutrients… all of that accompanied by habits like working out, etc. That is: being mindful and caring.

But between someone who does that on an omnivore diet and someone else on a vegan diet, the scale will tip in favor of the first one (generally speaking, because then we have to take into account hundreds of factors, some of them genetic). And a vegan that eats ultra-processed vegan food all the time and spend the day on the couch will be less healthy than an omnivore who cares about his diet and works out reasonably. The total context is what determines health, we can’t attribute magic properties to stopping to eat animals.

As any diet that implies cutting of whole groups of foods, it can cause multiple nutritional deficiencies, that maybe aren’t obvious in the beginning, but become serious as years go by. I already mentioned in my previous post several elements that are very difficult or impossible to get through a vegan diet and that are however indispensable for the organism.

The trap of comparisons

Still, many vegans, instead of warning about it and proposing solutions, ignore the problem and claim such deficiencies don’t exist. For example, with comparisons between animal and vegetable food saying that the second ones have in fact much more protein (or omega 3 fatty acids, etc.). Be careful with this kind of comparisons. Leaving aside the issue of the quality of those proteins and their bioavailability, they usually imply another manipulation: they take into account either only calories or only weight when it comes to telling their protein content, omitting the one that doesn’t go well with their theory.

For example, they say: “Almonds have almost double proteins than eggs”: right, per 100 g almonds have 22 g protein, and eggs only 12 (all those numbers are from MyFitnessPal). But eating 100 g of almonds (which is a lot) implies consuming 632 kcal, whereas eating 100 g of eggs (the average weight of 2 eggs is 120) will give us only 146. They’re therefore a quite more efficient source.

I was going to do the same thing with that comparison that goes around saying that broccoli has more protein than steak fillets, saying that the values they show are per 100 kcal, and how to eat 100 kcal of broccoli we’ll have to consume almost 300 g —would someone eat that?—, whereas a single fillet is already 100 g (150 kcal)… But even then, figures don’t square up, there are still 8’3 g of protein vs 16. So it’s plainly a lie. Always check the data before hitting the like button or sharing the information, especially when we’re not before a whole article with its context but just one image or graphic.

Let’s not be simplistic

In the nutritional field, we can rarely settle for simplifications, black and white, good and bad. There are a lot of factors into play, multiple correlations, we have to take into account genetics, lifestyle habits, the peculiarities of each person… and there’s still a lot to study about food itself, it’s a relatively new science. In general (again, with all the nuances you want) a little bit of everything is good, a lot of anything is bad. That is, variety and moderation. Apart from prioritizing less processed foods. What can’t be done is saying that for every person in the world the healthiest thing is to cut off a huge food group.

Reason 5: Ecology

Another motive that often makes people go vegan is the environment. And this time I can agree with them, because… the current meat production isn’t sustainable. Nevertheless, while I coincide in seeing the problem, I differ in the solution. I consider it’s better to support ethical meat production: being an ethical omnivore.

Plants and animals

And that is in the first place for everything I’ve already said: I don’t want to put in risk my physical health, and either my mental health (restricting food groups is a triggering for eating disorders). But it is also because I’m convinced that in the long term it’s the most beneficial option for the planet. The best systems are those that combine animal and vegetable production, because animals help to provide organic matter to the soil, contributing to its natural regeneration. Then we need less chemicals. An eco-friendly cattle industry is the key for an eco-friendly agriculture.

Because a lot is said about how bad the animal industry is for the environment (in most cases, with exaggerated data), but the production of veggies, cereals, etc., also has a carbon footprint. A very high one if we’re talking about products like some vegetable oils, but also when we have to bring things from far away. And those crops require huge amounts of water, as well as chemicals. Part of this is unavoidable; another part could be mitigated, and as I’ve said one solution would be the coexistence of animals and plants, which has been lost in our productive systems, that tend to single-crop farming.

Also, vegans talk about the gas emitted by cows, but not about how they can help to reduce greenhouse gas emissions through carbon sequestration: certain forms of grazing, that depend on the climate and need to be more studied but are all based on a more extensive system, contribute to increase this factor and therefore minimize the impact of this activity.

Solutions: fighting together

However, it’s still true that people eat a lot of unethically produced meat, and with the kind of systems that we’d need to introduce in order to make meat production sustainable, it’s not clear whether we would able to consume as much as now. But that doesn’t mean that there are people who need to compensate by not eating any, rather, that everyone should make little changes. That seems like an utopia… but maybe if some ecologist groups were more inclusive and encouraged every change instead of being sectarian and despising omnivores, there would be more acceptance.

Even so, I’m not naïve: a real change can only come if governments decree hard measures, and there are too many interests at stake as for this to happen overnight. I believe nevertheless that if we all join the fight together, put pressure on the authorities and above all convince the companies with our choices of consumption, little by little there will be changes. But for that we need to be able to fight all together. And I seldom feel welcome in the campaigns of the ecologists.

A special issue: animal wellbeing

Animals don’t have rights. But human beings do have duties towards them. And the treatment they’re given in many farms of massive production is condemnable. To me, this isn’t strictly an argument for veganism, since believing that something is bad is not the same as believing it’s good or bad depending on the conditions, as in this case. But I can’t either include it as one of my counter-arguments because it’s certainly what prevails nowadays and, given the price of the more ethical animal products, I understand that some people just choose not to consume them at all. It’s not the option I recommend, because despite everything I consider that people are more important than animals, and our body works better on an omnivore diet. But I get it. For a better solution, read the previous point.

I’m not going vegan. But I’m doing other things

Therefore, if I’m worried about the planet and the animals but I don’t believe in veganism, what can I do?

These are the things I’m already doing in my daily life:
  • Trying to be as eco-friendly as possible in other fields: light, water, not wasting plastic, recycling, reusing things, buying second-hand…
  • I have my own backyard hens that give me eggs. If this is not possible for you, buy category 1 eggs (free-range hens, with access to the outside). There are also 0, organically fed. Avoiding 2 (indoor housing) and 3 (cage farming).
  • I only buy animal products that have an animal welfare certificate.
  • I only buy cosmetic products that are natural, sustainable, vegan and haven’t been tested on animals.
  • When I buy new clothes (that is, almost never), I make sure it’s from sustainable brands that promote slow fashion.

In short, I consider myself an ethical omnivore. Knowing that I’m always going to be on the way and, therefore, without feeling guilty for my previous choices when I find out better ones and, at the same time, without believing I’m morally superior, since I’ll have to admit I’m not perfect. Are you going to join this challenge with me?


2 thoughts on “Why I’m not vegan: biological and philosophical arguments

  1. This is such a great blog post! My daughter who is 15 and is in recovery for anorexia, wants to be vegan when she comes home. It will be a battle because I know she needs the animal fats to heal her brain. The points you make in this post are all helpful arguments for me. Thank you so much!

    1. I’m glad I can help in such a difficult situation. Unfortunately, many people with eating disorders use veganism as a disguise to keep restricting but in a socially acceptable way.

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