The causes of vitamin B12 deficiency revealed
ca. 16 Minuten
Do you constantly feel sluggish despite taking care of your health? It could be due to a vitamin B12 deficiency. The causes are surprisingly varied and go far beyond diet—from hidden absorption problems to taking certain medications.
So often, the root of the problem isn’t on your plate, but hidden deep inside your body.
Why your energy isn’t a coincidence
Constant fatigue, trouble concentrating, or feeling like you just can’t get going—symptoms like these can make everyday life a real challenge. Many people blame stress, but often a significant nutrient deficiency is the cause. Vitamin B12, also known as cobalamin, is a real powerhouse for your body.
It’s essential for:
- Your energy production: B12 helps convert food into usable energy. Without B12, your body’s engine only runs at half speed.
- Your nervous system: The vitamin protects your nerve pathways like an insulating layer around a cable, ensuring smooth communication between your brain and body.
- Your blood production: It’s essential for producing red blood cells, which transport oxygen throughout your body.
The tricky thing is that a deficiency often develops over many years. Your liver can store vitamin B12, but when those reserves run low, the effects become noticeable. That’s exactly why it’s so important to understand the causes of vitamin B12 deficiency and get to know your own body better before the first serious symptoms appear.
The most common causes at a glance
The reasons for inadequate levels are complex and can be broadly divided into four categories. It’s not just about what you eat, but above all about what your body can actually absorb and use.
Vitamin B12 deficiency is often a silent process. Symptoms usually only appear once the body’s stores are already severely depleted. Taking proactive steps and understanding your body are therefore the best protection.
To give you a quick overview, we’ve summarized the main causes in a table.
The most common causes of vitamin B12 deficiency at a glance
| Cause category | Brief description | Typical examples |
|---|---|---|
| Diet | Dietary intake is too low. | Vegan or strict vegetarian diets, malnutrition in old age. |
| Malabsorption | The body cannot absorb B12 properly. | Intrinsic factor deficiency, chronic gastritis, celiac disease. |
| Diseases | Certain diseases disrupt B12 metabolism. | Crohn’s disease, small intestinal bacterial overgrowth (SIBO), pancreatic insufficiency. |
| Medications | Some medications interfere with absorption. | Stomach acid blockers (PPIs such as omeprazole), metformin (for diabetes). |
This overview shows that finding the cause sometimes takes detective work.
If you’d like to explore fatigue and nutrient deficiencies in more depth, you’ll find lots more useful information in our article about which vitamins are lacking when you’re tired.
The role of diet in B12 deficiency
One of the main causes of vitamin B12 deficiency is often right there on our plates. This makes sense, because your body can’t produce this essential vitamin on its own. You depend entirely on getting it from food. The catch is that vitamin B12 is produced almost exclusively by microorganisms and enters the food chain primarily through animal products.
Plant-based foods naturally contain no vitamin B12 that our bodies can use. That’s exactly what makes a purely plant-based diet one of the biggest risk factors for inadequate intake. So if you eat a vegan diet, you can’t avoid keeping a close eye on your B12 intake.
Why vegans and vegetarians need to be especially careful
For vegans, it’s clear: without targeted supplementation or fortified foods, a deficiency is virtually inevitable in the long run. But even as a vegetarian who avoids meat but eats dairy products and eggs, you should definitely keep an eye on it.
Although eggs and dairy products contain vitamin B12, the amounts are often not enough to reliably meet your daily needs. To get a safe amount, for example, you’d have to eat a considerable amount of cheese or several eggs every day—which isn’t always the best idea for other health reasons.
It’s important to understand: This isn’t about judging different dietary styles. It’s a biological fact that a plant-based diet alone cannot meet your B12 needs. Careful management is the key to a healthy plant-based diet.
To give you a better idea, here’s a quick overview of the best sources of B12:
- Top sources: Organ meats like liver are packed with B12.
- Good sources: Meat (especially beef), fish (such as salmon or herring), and seafood.
- Moderate sources: eggs, milk, yogurt and cheese.
Fortunately, there are good alternatives for everyone who eats a plant-based diet. Many manufacturers now specifically fortify their products with vitamin B12. These include plant-based drinks, breakfast cereals and meat substitutes, for example. So it’s always worth taking a quick look at the nutrition label!
Even people who eat both plant- and animal-based foods aren’t always in the clear
Even if you regularly eat animal products, you’re not automatically in the clear. A limited diet that’s low in nutrient-dense foods can also lead to inadequate intake. This particularly affects older people, who often have less appetite, or people with very irregular eating habits. Intake can quickly become a concern.
Choosing a particular diet has far-reaching effects on your body. If you’d like to explore the effects of a vegetarian lifestyle in more depth, you’ll find fascinating insights in our article about vegetarianism and genetic predispositions.
At the end of the day, diet is only one side of the coin. What good is the best intake if your body can’t absorb the vitamin properly in the first place? This is where a nutrient test can help provide clarity.
When your body can’t absorb the vitamin
Sometimes the problem isn’t on your plate at all, but much deeper in your body. Even if you actually get enough vitamin B12 from your diet, your body may simply be unable to use it properly. This is known as malabsorption - one of the most common and, at the same time, most insidious causes of vitamin B12 deficiency.
Imagine the vitamin’s journey through your body as a relay race. For vitamin B12 to reach the finish line - your cells - several stages need to work together smoothly.
The crucial role of the stomach and intestines
It all begins in the stomach. Vitamin B12 in food is bound to proteins and first needs to be “freed.” A healthy amount of stomach acid is absolutely essential for this. It essentially breaks the bond and releases the vitamin.
Once B12 is on its own, it needs a bodyguard for the rest of its journey through the digestive tract: the so-called intrinsic factor. This special protein is produced by cells in your stomach lining. It binds to the free B12 and protects it on its way to the final section of the small intestine - the only place where it can eventually be absorbed into the blood.
This process shows just how sensitive absorption really is:
The graphic makes it clear: if just one of these stages fails, the entire supply chain breaks down, inevitably leading to a deficiency.
When absorption is impaired
There are a number of factors that can disrupt this finely tuned process and are among the most common causes of vitamin B12 deficiency.
- Aging: As we age, the stomach often naturally produces less acid. With atrophic gastritis, a chronic inflammation, the stomach lining becomes thinner, reducing the production of both stomach acid and intrinsic factor.
- Gastrointestinal diseases: Inflammatory bowel diseases such as Crohn’s disease, as well as celiac disease, can damage the intestinal lining. This affects the very area where B12 is supposed to be absorbed. Read more in our article about celiac disease and gluten intolerance.
- Infections: The stomach bacterium Helicobacter pylori can cause chronic inflammation of the stomach lining and severely hinder B12 absorption.
- Surgery: People who undergo stomach-reduction surgery or other procedures on the gastrointestinal tract risk having the very areas responsible for B12 absorption removed or bypassed.
Because impaired absorption plays such a major role, it’s important to understand the underlying causes. In Germany, malabsorption is one of the main reasons for a deficiency, especially among older people. In fact, 10 to 50% of seniors are found to have a vitamin B12 deficiency, often due to precisely these age-related changes in the stomach.
The symptoms of a deficiency often develop gradually and are nonspecific, while the causes lie hidden deep beneath the surface. A blood test is therefore the only reliable way to get a clear picture of your B12 status and detect an absorption problem.
A nutrient test from mybody-x can help you do just that – quickly and easily from home. This way, you can find out whether your body can actually use the vitamin B12 you take in.
How medications affect your B12 levels
Did you know that everyday medications can be secret “vitamin robbers”? They’re often indispensable and help with many conditions, but as a side effect, they can seriously disrupt your body’s nutrient absorption. This is one of the most commonly overlooked causes of vitamin B12 deficiency, and it can play a huge role.
Some medications directly interfere with the complex absorption process we’ve already taken a closer look at. They disrupt the delicate balance in the gastrointestinal tract—and that’s crucial for the body to use vitamin B12.
The most common B12 robbers from the pharmacy
Two groups of medications are particularly in focus here. Why? Because they are extremely widespread and have been shown to increase the risk of B12 deficiency when taken long-term.
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Acid blockers (proton pump inhibitors): Medications such as omeprazole and pantoprazole are the standard treatment for heartburn and stomach ulcers. Their job is to drastically reduce stomach acid production. The catch is that, as you now know, stomach acid is the very first key to releasing vitamin B12 from your food. Less acid simply means less B12 is available for absorption in the first place.
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Metformin: This is one of the most important medications for treating type 2 diabetes. Studies have clearly shown that long-term use of metformin interferes with the small intestine’s ability to absorb the important B12-intrinsic factor complex. The exact mechanism is still being researched, but the connection is scientifically well established.
So if you take any of these medications over a long period, you should definitely keep an eye on your B12 status. A deficiency can creep in unnoticed over months or even years, until the symptoms suddenly appear.
Taking certain medications is no reason to panic, but it is a clear reason to be more mindful. Talk proactively with your doctor about vitamin B12 if you need to take acid blockers or metformin long-term.
This is very important: Never stop taking medication on your own. Being mindful and having regular checkups are the best way to ensure you’re getting what you need and prevent a deficiency.
The following image shows you a selection of blood tests that let you conveniently check your nutrient status, including your vitamin B12 level, from home.
These tests give you the opportunity to take your health into your own hands. You can find out early on whether a medication-related cause could be playing a role in your vitamin B12 deficiency.
Genetics and lifestyle as underestimated risk factors
Sometimes the causes of a vitamin B12 deficiency aren't obvious. In addition to diet, illnesses, and medications, there are other pieces of the puzzle that are often overlooked. Sometimes these risks are literally in our genes, or they develop over the years through certain habits.
For example, there are congenital metabolic disorders that disrupt the processing of vitamin B12 from birth. Although such genetic causes are rare, their consequences can be serious.
Your genetic blueprint
Some people are born with a genetic predisposition that makes it difficult for their bodies to use vitamin B12 properly. The vitamin is absorbed, but the crucial conversion into its active form simply doesn't work.
Such congenital factors are receiving increasing attention in Germany, especially in newborn screening. The Genetic Diagnostics Commission (GEKO) has issued clear recommendations for the early detection of such metabolic disorders. No wonder, since if left untreated, they can lead to severe developmental disorders. Find out more about the background to early detection on the IGeL Monitor website.
How your lifestyle affects your B12 supply
Your daily life can also significantly disrupt your B12 levels. Excessive alcohol consumption plays a particularly harmful dual role.
- Liver damage: Your liver is the body's main storage site for vitamin B12. If you regularly drink too much alcohol, you damage your liver cells. This impairs their ability to store this important vitamin and release it when needed.
- Impaired nutrient absorption: Alcohol also irritates and damages the mucous membranes throughout the digestive tract. As a result, your small intestine is much less able to absorb B12 and other vital nutrients.
Your lifestyle is a powerful lever for your health. While you can't change your genetics, you have full control over your habits.
Other chronic conditions can also indirectly lead to a deficiency. For example, pancreatic insufficiency means that too few digestive enzymes are produced. But these enzymes are needed to separate B12 from its transport proteins in the small intestine - only then can the body absorb it.
So you can see: Finding the cause can be quite complex. A simple nutrient test from mybody-x gives you clarity about your B12 status, so you can take the right steps for your health.
How to reliably identify a B12 deficiency
Do you feel constantly tired and can barely concentrate, but aren’t sure whether a vitamin B12 deficiency is really to blame? Many people know the feeling, because the symptoms are often vague and could point to all sorts of things. Instead of fumbling around in the dark, you need clear facts. And the only way to get real certainty about your B12 status is a blood test.
That’s the only way to see in black and white how your levels are doing and whether any of the many causes of vitamin B12 deficiency apply to you. Fortunately, this kind of analysis is easier than ever.
What your blood reveals about your B12 levels
A blood test looks at specific values that paint an accurate picture of your B12 status. In the past, total vitamin B12 in blood serum was usually measured. The problem is that this value isn’t very sophisticated. It lumps together active B12, which the body can use, and an inactive form that is merely bound to other proteins as a “passenger” and does nothing for you.
So a normal total B12 level can give you a false sense of security, even as a deficiency is already developing.
Measuring holotranscobalamin (Holo-TC) is far more modern and informative. Think of it this way: it’s the VIP value that detects only “active B12”—that is, only the molecules that actually bind to the right transport protein and can be absorbed by your cells. Holo-TC is like your early warning system, sounding the alarm long before your total B12 level even starts to drop.
The easy way to get more certainty: a home test
The good news is that you don’t have to make a special trip to the doctor or sit in the waiting room to get these answers. With a nutrient deficiency test from mybody-x, you can simply take matters into your own hands—all from the comfort of your home.
The process couldn’t be easier or quicker:
- Collect your sample: With the test kit, briefly prick your fingertip and collect a few drops of blood yourself. It really is simple.
- Send in your sample: Place your sample in the enclosed return envelope and send it directly to our certified German specialist laboratory.
- Get your results: Your analysis will be available in your personal customer account shortly—discreetly, securely, and presented in a way that’s easy to understand.
Here’s how to take control of your health data again and finally make decisions based on facts. If you want to take a deeper dive into how to identify different nutrient deficiencies, you’ll find even more valuable information in our comprehensive guide to the nutrient deficiency test.
The most important questions and answers at a glance
Finally, let’s clear up the most common questions we keep getting about the causes of vitamin B12 deficiency. This will leave you well prepared and able to put your knowledge to good use.
Can stress cause a B12 deficiency?
The short answer is: not directly. Stress alone neither blocks vitamin B12 absorption nor stops you from getting it through your diet. But - and this is the key point - chronic stress can lead to behaviors that significantly increase the risk of a deficiency.
Who hasn’t experienced it? During stressful periods, people are more likely to reach for unhealthy food, their diet becomes less varied, or their alcohol consumption increases. Ongoing stress can also contribute to gastrointestinal problems such as gastritis, which in turn interferes with B12 absorption. Stress is therefore more of a hidden accelerant than the actual cause.
How quickly does a deficiency develop?
This varies greatly from person to person and depends largely on the cause and your personal B12 stores. Your liver acts as a real reservoir and can store the vitamin for three to five years.
So if you start eating a purely vegan diet but don’t take supplements, it can actually take years for the first symptoms to appear. It’s a very different story if you have an absorption disorder - for example, after stomach surgery. Your stores can then be depleted much faster.
Important to know: A deficiency almost always develops gradually and quietly. Symptoms often only become noticeable once your stores are already dangerously depleted. That makes early monitoring all the more important!
Do people in Germany generally get enough B12?
Broadly speaking: yes. According to the National Nutrition Survey II, most men and women in Germany actually consume more vitamin B12 than recommended. You can read more in the findings on vitamin B12 intake from the German Federal Institute for Risk Assessment.
The real problem is therefore less often intake and much more often an undetected absorption disorder. This is exactly why even people who eat a balanced diet that includes both plant and animal foods can develop a deficiency. Without a test, you’re often completely in the dark.
Are you ready to finally get clarity about your vitamin B12 levels and take control of your health? A mybody-x blood test gives you answers quickly and easily, right from the comfort of your home. Find the right test for you now at https://mybody-x.com.
