If you are lacking vitamin B12, this can show up in very unusual ways—even in your mouth—often before you realize something serious is happening in your body. This is precisely why you should pay close attention to what your tongue, gums, and entire oral cavity are telling you. The body never lies.

What We Know About B12

Vitamin B12 is crucial for blood, nerves, the brain, the heart, and even fertility. But when it starts to run low, we often think we’re just tired or feeling down, so these warnings are often ignored. Studies from 2020 and 2023 show that as many as 23% of Europeans suffer from mild or moderate B12 deficiency, with most people completely unaware that this is the cause of their problems.

Vitamin B12 is one of those vitamins that, unlike others, is not found in plants. It is found almost exclusively in animal-based foods: meat, eggs, fish, and dairy products.

This vitamin is essential because:

• it helps form red blood cells, which carry oxygen,
  
  
• it protects the nerves and ensures signals travel properly along them,
  
  
• it is involved in the formation of DNA,
  
  
• it affects heart function,
  
  
• it prevents fatigue and loss of concentration.

When we begin to lose it, this can quietly accumulate for months or even years. A Harvard Health study from 2021 showed that the body can store B12 in the liver for about 3 to 5 years, which means that problems are often noticed too late. And in fact, the tongue and mouth are the first alarm, signaling a deficiency. Hidden signs of B12 deficiency that are often overlooked include:

1. Sores and Canker Sores – Small Signs That Say a Lot
   
   Canker sores are small painful ulcers that appear on the tongue or gums. This is one of the first warning signs of vitamin B12 deficiency. The word "canker sore" indeed means a small painful wound in the mouth. It is an ulcer that occurs due to a weakened immune system or a lack of nutrients.
   
   WebMD reports that people often think canker sores are caused by stress, acidic foods, or biting the tongue, which is partly true, but for many people, B12 deficiency is actually behind it. In 2022, researchers in Turkey studied 98 people with persistent canker sores and found that 53% had low levels of vitamin B12.
   
   If your canker sores are frequent, painful, larger than 4 mm, or appear every month, this is an important sign to check your B12 levels.
   
   
2. Smooth and Shiny Tongue – A Silent Sign That Papillae Are Disappearing
   
   When your body starts to run low on vitamin B12, something unusual can happen: your tongue literally becomes smooth. It loses those small bumps called papillae. Papillae are tiny projections on the tongue that sense taste and assist with chewing.
   
   When papillae disappear, the surface of the tongue becomes:
   • smooth,
     
     
   • shiny,
     
     
   • red or even purple,
     
     
   • sensitive or painful.
   This condition is called atrophic glossitis, meaning shrinkage of the tongue’s papillae. It sounds scary, but what’s more important is understanding that your body is loudly telling you it lacks a key vitamin.
   
   A 2020 study found that 68% of people with pronounced B12 deficiency had exactly this change in their tongue, which often reverses when B12 levels are restored.
   
   
3. Swollen, Burning, or Red Tongue – When Every Food Stings
   
   Harvard Health confirms that a swollen and sensitive tongue is one of the most common signs of B12 deficiency, especially in women and in those over 60. The tongue can be so sensitive that even plain water stings.
   
   In 2025, researchers in Berlin reported that in people with severe B12 deficiency, the tongue’s volume increased on average by 12%, enough to cause a burning sensation, pain, and problems with eating.

Other Warning Signs of B12 Deficiency

B12 deficiency often causes many other symptoms. These are often attributed to the season, stress, or age, but that’s not always the case. They may include:

• persistent fatigue,
  
  
• tingling in hands and feet,
  
  
• reduced muscle strength,
  
  
• blurred vision,
  
  
• memory and concentration problems,
  
  
• feelings of confusion,
  
  
• lower mood,
  
  
• depressive feelings,
  
  
• faster forgetting.

A study in the UK (NHS, 2023) showed that people with severe B12 deficiency have a 130% increased risk of nerve problems and a 52% increased risk of depression.

Why Does Vitamin B12 Deficiency Happen? Even If You Eat Meat ...

Many people think B12 deficiency only happens to vegans or vegetarians. In reality, it’s more often due to absorption problems. The body simply cannot extract what it needs from food. This is why deficiency most often occurs:

• in people over 60 (in as many as 62% of them),
  
  
• in people with prolonged stress (the hormone cortisol blocks absorption),
  
  
• in individuals with stomach or intestinal inflammation,
  
  
• due to taking certain medications (e.g. stomach medicines reduce absorption by 80%),
  
  
• in people who consume too little protein,
  
  
• in people after stomach surgery,
  
  
• in those with weakened immune systems.

Between 2021 - 2024, endocrinologists in the USA reported that for 1 in 10 people who do eat enough meat, B12 deficiency still develops because of poor stomach absorption.

How Much Vitamin B12 Do You Really Need?

NHS recommends 1.5 micrograms of vitamin B12 per day for adults. But note: this is the minimum value. A 2024 study proposed that people over 50 should get at least 3?4 micrograms, since absorption can decrease by as much as 70% with age.

You can find vitamin B12 in:

• meat (beef contains about 2.6 µg per 100 g),
  
  
• fish (sardines contain up to 8.9 µg per 100 g),
  
  
• eggs (1 egg contains about 0.6 µg),
  
  
• dairy products,
  
  
• fortified cereals.
  
  
• For better absorption, it’s also good to eat foods rich in folate (spinach, legumes).

How You Can Help Yourself at Home

Folk medicine knows several ways to strengthen the body when it begins to lack certain nutrients. Vitamin B12 is no exception.

1. Bone Broths and Soups from Animal Parts Our ancestors cooked them for hours, as such soups are full of minerals, amino acids, and B12. A 2023 study showed that with long cooking, up to 1.2 µg of vitamin B12 can be released per serving.
   
   
2. Sardines in Oil – Little B12 Bomb One can (about 120 g) contains about 10 µg of vitamin B12, more than 6 times the minimal daily value. Cheap, quick, and very effective.
   
   
3. Homemade Kefir or YogurtBecause dairy products naturally contain B12, their fermentation helps to stabilize the vitamin even more. Studies from 2020 confirmed that fermented dairy products increase B12 availability by 28%.
   
   
4. Homemade Yeast SpreadsBrewer's yeast is often fortified with vitamin B12. One tablespoon can contain from 1 to 4 µg of the vitamin.
   
   
5. Avoid Foods that Irritate Oral MucosaIf you have canker sores or a sensitive tongue, avoid vinegar, citrus, spicy dishes, and nuts that may irritate the mucosa.How to Check If You Are Lacking B12 in 7 Days (DIY Test)
   
   If you want to check your vitamin B12 status using a home method, you can observe:
   • if your fatigue is increasing (measure how quickly you become tired—if this gets shorter, it's a warning sign),
     
     
   • if you repeatedly get canker sores (more than 2 per month),
     
     
   • if your tongue is smoother, shinier, or redder,
     
     
   • if you notice tingling in your hands and feet,
     
     
   • if it's harder to get up in the morning than before,
     
     
   • if you’re forgetting more than usual.

If you observe 3 or more signs, you have a high likelihood of deficiency. If your tongue is very swollen, you have trouble swallowing, you don’t feel better in 10 days, or you experience vision problems or confusion, it is highly recommended to get a blood test for vitamin B12. These tests are accurate and will show your levels in a few days.

In severe deficiency, B12 injections are sometimes prescribed, which can restore your levels in a few weeks.

Listen to Your Body, Fix Your Diet, and Choose Home Solutions

The mouth, tongue, and gums are often the first to show that your body is missing something. Sores, a smooth tongue, or burning sensations are not just a passing annoyance, but a clear signal that you have a vitamin B12 deficiency. By listening closely to your symptoms, making some dietary changes, and using simple home remedies, you can drastically improve your condition in just a few weeks.

Let us remind you: vitamin B12 is one of the few vitamins you should never ignore, as it affects your nerves, heart, blood, and brain. Between 2020 and 2025, it has become clear that deficiency is spreading much faster than before, partly due to stress, fast food, and medications.

So take care of yourself: you will feel fresher, have clearer thoughts and more energy, and your tongue will thank you.