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Vitamin B12: The Mysterious Nutrient Vegans Keep Getting Yelled At About

  • Writer: Emanuele Bortolotto
    Emanuele Bortolotto
  • Jul 16
  • 9 min read

Updated: Sep 6


It’s late on a Saturday night here inKonala, Helsinki, a time for quiet reflection. And as an investigator of our modern anxieties, I am reflecting on a specific type of social interaction, a strange and deeply predictable ritual. It goes like this: a person, let’s call them the “vegan,” is at a social gathering, peacefully minding their own business, perhaps enjoying a canapé that doesn’t contain any obvious animal parts. Then, another person, let’s call them the “Concerned Uncle,” approaches. He has a look of profound, almost pained, sincerity in his eyes. He leans in, and with the gravity of a man about to reveal a state secret, he asks the question: “But where do vegansu get their B12?!” 🤔


The question hangs in the air, thick with unspoken assumptions about fatigue, nerve damage, and general bodily disintegration. The vegan, I have observed, then has to pause, take a deep breath, and launch into a condensed, slightly weary TED Talk on microbiology and modern agriculture. It’s a scene that plays out millions of times a day, a tiny, recurring drama in the grand theatre of our dietary debates. It’s a verbal duel with all the epic, repetitive grandeur of a Rhapsody of Fire song, but with more awkward pauses and less dragons. 🐉

This whole phenomenon fascinated me. Why this one vitamin? What is this mysterious nutrient that has become the number one weapon in the arsenal of every anti-vegan debater? I decided to launch a full-scale investigation into the bizarre, microscopic, and surprisingly dirty world of Vitamin B12.


What Is This Stuff? A Journey Into the Heart of a Molecule


Before I could understand the panic, I first had to understand the subject. What, in the name of all that is holy, is Vitamin B12? My investigation revealed that it’s not just a vitamin; it’s a diva. It’s a massive, incredibly complex molecule built around a single, metallic atom of cobalt, which is why its scientific name is cobalamin. It’s the gothic cathedral of the vitamin world—intricate, essential, and a little bit dramatic. 🦇

Its job description in the human body is terrifyingly important. I’ve read a lot of very dry biochemistry textbooks on this, and I’ve decided they make it sound much less alarming than it is. B12 is, in essence, the master electrician of your entire nervous system and the foreman of your blood cell factory.


  • Nerve Function: It is absolutely essential for building and maintaining the myelin sheath, the fatty, insulating layer that surrounds your nerve cells. Without it, your nerves are like live wires with the plastic stripped off, leading to short circuits, signal loss, and general chaos. It's the difference between a high-speed internet cable and two tin cans connected by a piece of damp string.

  • DNA Synthesis & Red Blood Cells: It’s a key player in the creation of your DNA and the formation of healthy red blood cells. You know, just minor, unimportant stuff like creating new life and carrying oxygen to every part of your body so you don’t die.

Without enough B12, things start to go very, very wrong. We’re talking about a slow, creeping, and deeply unpleasant unraveling of your body and mind. It’s not a fun deficiency.


The Great Plot Twist: Where B12 Actually Comes From (It's Not a Cow) 🐮


This is the part of my investigation where the entire debate turned on its head. This is the secret that, once you know it, makes the “where do you get your B12?” question so profoundly ironic. After spending a week buried in microbiology textbooks that smelled faintly of dust and despair, I emerged with the truth. And it is this:


Vitamin B12 is not made by plants. And it is not made by animals.

Let that sink in for a moment. So, where does it come from? It is produced exclusively by microorganisms. Tiny, single-celled bacteria and archaea that live in the soil, in the water, and in the guts of animals. That’s it. They are the only B12 factories on Planet Earth. 🏭

This is a shocking revelation. It means that for most of human history, we likely got our B12 from the environment. We drank from untreated streams and rivers. We ate unwashed vegetables, pulled straight from the soil, still covered in these B12-producing microbes. Our ancestors were, in essence, getting their vitamins by being a little bit filthy.


In our modern, sanitized world, where we wash our vegetables with chlorinated water and have a crippling fear of germs, we have effectively sterilized B12 out of our diet. Animals get their B12 by eating this contaminated food and water, or, in the case of ruminants like cows, from the bacteria in their own complex digestive systems.

But here is the secret that no one seems to know, the second plot twist in our B12 conspiracy. In modern factory farms, most livestock are no longer living in a way that allows them to get B12 naturally. They are not grazing in fields, eating dirt-covered grass. They are living in confined spaces, eating a controlled diet of grain. So, the industry does something very simple. They add B12 supplements to the animal feed.


So, when a person says, “I get my B12 from a steak,” what they are often really saying, without realizing it, is, “I get my B12 from a supplement that was fed to a cow, which I then had killed and ate.” It’s just a very inefficient, secondhand, and brutal way of taking a vitamin. The animal is just the middleman. The concerned uncle is, in fact, also getting his B12 from a supplement; he’s just filtering it through a cow first.


The Vegan's Dilemma: The Empty Plate


This modern, sanitized world creates a unique problem for vegans. While omnivores are getting a dose of secondhand supplements from their meat and dairy, the vegan plate is, by default, B12-free.

My investigation looked into the many hopeful but ultimately false rumors about plant-based B12 sources.


  • Nutritional Yeast: The yeast itself does not produce B12. The "nooch" in your pantry is only a good source if the label explicitly says that B12 has been added to it in a factory.

  • Seaweed (like Spirulina): This is the most dangerous myth. My research confirms that these sources contain B12 analogues, which are "imposter" molecules. They are like a key that looks like the B12 key but is cut incorrectly. It can get stuck in the lock (your body's B12 receptors) and actually block the real, useful B12 from getting in. 🚫 It’s not just useless; it’s a saboteur.

  • Unwashed Organic Veggies: The amount of B12 you’d get from a bit of dirt is wildly inconsistent and nowhere near enough to meet your body's needs. Plus, you run the risk of getting other, less friendly bacteria that will make you have a very bad day.

The conclusion is inescapable. If you are a vegan in the 21st century, you must find a reliable, intentional source of Vitamin B12. Period.


The Slow Creep of Deficiency: A True Horror Story 👻


What happens if you don't? My investigation into the symptoms of B12 deficiency was, frankly, terrifying. The problem is that it’s a slow and sneaky process. Your liver can store a significant amount of B12, so a deficiency can take years to manifest. But when it does, it's a multi-system failure.


The early symptoms are vague and easy to dismiss as just "the stress of modern life":

  • Constant, profound fatigue that no amount of coffee can fix. 😴

  • Brain fog and a general feeling of being mentally slow.

  • Mood swings, irritability, and even depression.

As it progresses, the neurological symptoms, caused by the breakdown of the myelin sheath, begin to appear:

  • A strange tingling or numbness in the hands and feet, like a persistent pins-and-needles sensation.

  • Balance problems and a general sense of unsteadiness.

  • Memory loss that can be so severe, especially in older adults, that it can mimic the symptoms of dementia.

And in the final, most terrifying stage, this neurological damage can become permanent. This is not a game. This is not something to be lazy about.


The Solution: A Very Simple and Un-Scary Guide


The good news is that preventing this horror story is the easiest and cheapest thing in the world. As an investigator, I have concluded that there are two main, foolproof methods.


Method 1: The Supplement Strategy


This is the most direct and reliable method. You simply buy a bottle of vegan B12 supplements. They are tiny, they are cheap, and they are incredibly effective. You have two main choices for your dosing strategy, based on the fact that our bodies are weirdly bad at absorbing B12 from a single, large dose.


  • The Daily Dose: A small, daily supplement of at least 25-100 micrograms (mcg). This is a great way to build a consistent habit.

  • The Weekly Mega-Dose: A larger, once-or-twice-a-week supplement of 1,000-2,500 mcg. This works because while you only absorb a small percentage, the total amount absorbed is enough to last you for several days. Your liver is great at storing it, so the weekly dose is a fantastic option for the forgetful among us.


Method 2: The Fortified Food Fleet


This method involves getting your B12 from foods that have had a synthetic, vegan version of B12 added to them during production. This is a great way to build a nutritional safety net. Your best friends here are:

To rely on this method alone, you need to be very diligent, eating at least two to three servings of these foods, spread throughout the day, every single day, to ensure you are getting enough. For most people, a combination of fortified foods and a weekly supplement is the most practical and stress-free approach.


Questions from the Internet



Questions from the Internet: "What's the difference between cyanocobalamin and methylcobalamin?"


This is a fantastic, nerdy question that I investigated with glee. These are the two most common forms of B12 found in supplements.

  • Cyanocobalamin: This is the most stable and most studied form. It’s synthetic and very cheap to produce. Your body has to convert it into the active form, but this is a very simple process for most people.

  • Methylcobalamin: This is a "natural," active form of the vitamin. It's less stable and more expensive. Some people, particularly heavy smokers or those with certain kidney problems, may benefit from this form, as their ability to convert cyanocobalamin can be impaired.

    For the vast majority of vegans, my research confirms that the cheaper, more stable cyanocobalamin is perfectly effective and is the form recommended by most major vegan health organizations.


Questions from the Internet: "But my non-vegan uncle had a B12 deficiency! What's up with that?"


This is a brilliant point. B12 deficiency is not a "vegan problem." It's a "human problem," and it's particularly common in older adults. As we age, our ability to produce stomach acid and a special protein called Intrinsic Factor (which is needed to absorb B12 in the gut) declines. This means that many older people, even those who eat a lot of meat, can't absorb the B12 from their food effectively. This is why B12 deficiency is a common issue for the elderly, regardless of their diet. Your uncle's steak might contain B12, but his gut might not be able to unlock it.


The great B12 debate is often used as "proof" that a vegan diet is somehow unnatural or lacking. But as we've seen, it's a problem of our modern world, not the diet itself. For a full investigation into the other common myths and tired arguments you'll face, check out my comprehensive field guide: ["But Lions Eat Meat!": A Field Guide to Debunking the Most Tired Anti-Vegan Arguments].


The Conclusion: It's a Supplement, Not a Failure


So, after this deep dive into the microscopic world of our most controversial vitamin, what have I learned?

I’ve learned that the constant, panicked questioning of vegans about their B12 status is both deeply ironic and profoundly misguided. The fact that vegans need to supplement with B12 is not a sign that their diet is a failure. It is a sign that they are living in the 21st century.

Taking a B12 supplement is not a shameful admission of defeat. It is a smart, simple, and scientifically sound act of health maintenance. It is the easiest and most important part of a thriving, modern, plant-based life. So, the next time your concerned uncle asks you where you get your B12, you can smile, look him dead in the eye, and say, "From a supplement. The same place your cow probably got it." 😉

Of course, B12 is just one part of the nutritional puzzle.


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