Signs You May Be Deficient in Vitamin B12

Ethan Hartwell | April 2, 2026

The role of vitamin B12 is well known among vegetarians and vegans, because this vitamin has the particularity of being present only in animal-origin foods. Those who eat little or none of this group of foods are more likely to be deficient.

Regardless of your diet, here are the signs that may alert you to a vitamin B12 deficiency.

What is Vitamin B12?

Vitamin B12 is essential for cardiovascular health on several levels. The combination of vitamin B9 (folate) and B12 is crucial for reducing homocysteine levels, which can lead to cardiovascular disease when elevated.

Moreover, cardiovascular diseases remain one of the leading causes of death worldwide.

Additionally, B12 is essential for maintaining healthy skin, hair, and nails, because it plays a very important role in cell replication.

Sources of Vitamin B12

As noted above, vitamin B12 is present in animal-derived foods: meat, fish, seafood, dairy products and eggs. Some algae also contain it.

If you follow a vegan diet, you will absolutely need to supplement with quality dietary supplements. Vegetarians who eat certain animal products are less exposed to risks.

Note, however, that vitamin B12 is produced exclusively by certain bacteria, whether it is found in animal products or in dietary supplements.

How to know if you’re deficient in vitamin B12?

Because daily requirements are small and the body’s stores are substantial, a vitamin B12 deficiency will be difficult and slow to notice: it may take several months or even years.

If in doubt, it’s best to consider a blood test or a urine test. Conversely, know that too much vitamin B12 does not pose a danger since it has no toxicity risk, even at very high doses.

Anemia

Do you feel weak, short of breath with little effort, frequently lightheaded or off-balance? Do you have heart palpitations? Is your skin pale and do you shed more hair than usual?

It might be a sign of anemia caused by this vitamin B12 deficiency. In that case, don’t hesitate to speak with your doctor. They may order a blood test to check.

Oral signs

Has your tongue changed in appearance? A vitamin B12 deficiency can cause various mouth issues, such as mouth ulcers or glossitis, i.e., inflammation of the tongue.

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Vitamin B12 and the digestive system

A B12 deficiency will have consequences for the digestive system. It can cause nausea, constipation, gas, and loss of appetite.

Conversely, digestive disorders can lead to poor absorption of vitamin B12. These include stomach, liver, or intestinal conditions or the use of certain medications.

In case of severe deficiency

People with severe B12 deficiency will show additional symptoms. They will be neurological in nature, such as numbness, tingling, and poor coordination. The lack of B12 also affects the mental and cognitive sphere, with mood disturbances and sometimes depression.

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Ethan Hartwell

I break down everyday products to understand what they truly contain and what they imply. My goal is simple: make information clear and useful so people can make more responsible choices without complexity or unnecessary noise.