Recognizing Vitamin B12 Deficiency: Symptoms, Causes, and What You Can Do About It

What does vitamin B12 do in your body?

Vitamin B12, also known as cobalamin, is involved in three important processes in your body. It helps produce energy from your food, keeps your nervous system in good condition, and is necessary for the production of red blood cells, the cells that transport oxygen throughout your body.

Your body does not produce B12 itself. It is produced by microorganisms and reaches you through animal products such as meat, fish, eggs, and dairy. Because your body does not build up a large reserve of B12 and requires a small amount daily, a deficiency can develop if the supply through diet or absorption in your intestines is not in order for an extended period.

Symptoms of B12 deficiency: what to look out for?

A vitamin B12 deficiency usually develops gradually, which makes it difficult to recognize. A vitamin B12 deficiency can cause nerve problems and anemia:

What symptoms might you experience from nerve problems

• tingling in your hands and feet
• reduced sensation in your fingers
• reduced sensation in your feet, as if walking on cotton wool
• a leg feels cold
• movements become less precise, for example, you drop things
• your balance is poor

What symptoms might you experience from anemia

• feeling tired and weak
• breathing breath quickly when you exert yourself
• getting dizzy
• feeling like you are going to faint
• your heart suddenly beats fast
• sweating
• headache
• you constantly hear a sound in your head (tinnitus)

These symptoms can also have many other causes. Therefore, a vitamin B12 deficiency cannot be diagnosed based on symptoms alone; a medical examination is required for this.

Consequently, a prolonged and untreated deficiency can lead to anemia. Your red blood cells become larger than normal but function less effectively, causing oxygen to be transported less efficiently throughout your body. Do not ignore the symptoms for too long: the longer a deficiency remains undetected, the greater the chance that the nervous system will sustain damage that will not fully recover.

Who is most at risk of a deficiency?

Not everyone is at the same risk of a vitamin B12 deficiency. The main risk groups are:

Vegans and some vegetarians. Vitamin B12 occurs naturally almost exclusively in animal foods. Vegans therefore need a reliable source in the form of supplements or B12-fortified products. For vegetarians, the risk depends on the amount of eggs, dairy, and fortified products they consume.

Elderly people. As people age, the stomach may produce less stomach acid. Stomach acid is necessary to release B12 from dietary proteins. As a result, absorption from food may decrease, even when the diet contains sufficient B12.

People with autoimmune atrophic gastritis or pernicious anemia. In these cases, the stomach produces little or no intrinsic factor, severely disrupting the normal absorption of B12.

People with stomach or intestinal disorders or after surgery. Celiac disease and Crohn's disease, especially when the last part of the small intestine is affected, can reduce absorption. Gastric reduction surgery or the removal of part of the stomach or small intestine also increases the risk.

Users of certain medications. Long-term use of metformin and antacids, such as omeprazole, can reduce B12 absorption. The risk depends, among other things, on the dosage and duration of use.

People who use nitrous oxide regularly or frequently. Nitrous oxide can deplete vitamin B12 in the body. This can lead to a functional B12 deficiency, sometimes even when the measured B12 level is not significantly reduced. This can cause, among other things, tingling, loss of sensation, muscle weakness, and difficulty walking.

Pregnant people and people who are breastfeeding with limited B12 intake. During pregnancy and breastfeeding, the need for B12 is slightly higher. Especially with a vegan diet, reduced absorption, or an existing deficiency, sufficient supplementation is important for both parent and child.

Why a supplement is not always enough

If you are taking vitamin B12 but your symptoms do not improve sufficiently, there can be several causes. The dosage or duration of treatment may be insufficient, the supplement may not be taken consistently, there may be reduced absorption, or the symptoms may have another cause. Furthermore, neurological symptoms may recover slowly and sometimes persist partially.

For the normal absorption of vitamin B12, the stomach produces intrinsic factor. B12 binds to this and is subsequently absorbed in the final part of the small intestine. In pernicious anemia, an autoimmune reaction leads to a deficiency of intrinsic factor, permanently disrupting this normal absorption. However, a small amount of B12 can also be passively absorbed without intrinsic factor. Therefore, high-dose oral B12 can sometimes be effective even in cases of absorption problems.

Cyanocobalamin, methylcobalamin, and hydroxocobalamin are different forms of vitamin B12. There is no convincing evidence that methylcobalamin is better absorbed or more effective than cyanocobalamin. In the Netherlands, cyanocobalamin is often used as an oral treatment. Hydroxocobalamin is usually administered by injection, for example in cases of severe anemia, clear neurological symptoms, or insufficient effect of tablets. Deficiencies in, for example, folate or iron can cause similar symptoms and abnormalities in the blood count and sometimes coexist with a B12 deficiency. Therefore, if symptoms persist despite treatment, further medical assessment is important rather than automatically adding multiple supplements. Where is vitamin B12 found? A list of food sources

Vitamin B12 occurs naturally primarily in animal foods:

• Liver and other organ meats
• Meat and poultry
• Fish
• Shellfish, such as mussels and oysters
• Eggs
• Dairy products, such as milk, yogurt, and cheese

Anyone who consumes sufficient amounts of these products has a low risk of deficiency due to insufficient intake. However, a deficiency can still occur if the body is unable to absorb B12 properly.

Plant-based foods do not naturally contain a reliable amount of vitamin B12. B12 has been added to some products, such as plant-based milk substitutes, meat substitutes, and breakfast cereals. Always check the label for this, as not all plant-based alternatives are fortified.

Vegans are advised to use B12-fortified products daily and to take a reliable B12 supplement, even when they have no symptoms. This can prevent a deficiency in the long term.

How much vitamin B12 do you need per day?

For adults, the recommended daily allowance is 2.8 micrograms of vitamin B12. During pregnancy, this is 3.3 micrograms per day, and during breastfeeding, 3.8 micrograms.

Anyone who eats sufficient and varied animal products or B12-fortified foods and can absorb B12 normally generally gets enough through their diet.

Supplements sometimes contain much more B12 than the daily requirement. This is partly because the body absorbs only a small percentage at high doses. No acceptable upper limit has been established for vitamin B12, and high doses are generally considered safe. However, taking more B12 offers no additional health benefit without a deficiency. High therapeutic doses are primarily intended for people with a confirmed deficiency or an increased risk.

When is a blood test useful?

A blood test can be useful for persistent symptoms such as unexplained fatigue, tingling, loss of sensation, or concentration problems. This applies especially if you belong to a risk group.

Usually, the amount of vitamin B12 in the blood is examined first in combination with the blood count. Because these symptoms can have many different causes, a single B12 value does not always provide an immediate clear answer.

Is the result borderline or does it not fit well with the symptoms? Then an additional test can be requested, for example for methylmalonic acid (MMA). This value can help assess whether the body actually has too little usable B12.

Preferably have blood drawn before you start B12 supplements, as these can influence the result. Are you already using a supplement? Then mention which product you are using, how much, and for how long. Do not stop a prescribed treatment yourself.

Do you have tingling, loss of sensation, muscle weakness, or problems with walking and balance? If so, have this assessed in a timely manner. In the case of clear neurological symptoms, the doctor may decide to start treatment even before all results are known.

What is a normal B12 value?

There is no universal normal value for vitamin B12. Measurement methods and reference ranges may vary by laboratory. Therefore, always look at the limits stated with the result and have the value assessed in combination with symptoms, risk factors, and any supplement use.

A general classification is often used:

• Lower than 148 pmol/L: a reduced B12 value; with corresponding symptoms or abnormalities, a deficiency is likely.
• 148 to 250 pmol/L: a low-normal value or ‘grey zone’. A deficiency is less likely, but cannot be completely ruled out.
• Higher than 250 pmol/L: a deficiency is generally unlikely, but not completely ruled out in all situations.

A B12 determination in the blood (serum) shows how much B12 is circulating, but not always whether your cells can actually use enough of it. As a result, the result may appear normal, while there is still a functional deficiency.

Methylmalonic acid (MMA) is a substance that rises in the blood when cells have too little usable B12. It is therefore a more sensitive marker for a functional deficiency, especially at a borderline value or a result in the gray zone. MMA is not routinely included in an initial screening, but can provide additional clarity in consultation with a doctor in case of persistent symptoms or doubt.

In the case of a value in the grey zone and appropriate symptoms or risk factors, additional testing for methylmalonic acid (MMA)