What happens to your body when you have vitamin B12 deficiency

Vitamin B12 deficiency is common among older adults, vegetarians, vegans, and people with certain medical conditions because this vitamin is primarily found in meat, fish, dairy, and fortified foods. When levels drop, symptoms such as fatigue, headaches, muscle weakness and depression may appear, but diagnosis can be tricky because they overlap with many other conditions.

1. You might feel weak and tired

Vitamin B12 plays a role in the production of red blood cells (RBCs). These cells carry oxygen throughout the body. Oxygen helps your body produce energy.

Vitamin B12 deficiency leads to the production of defective red blood cells. Anemia is when you don’t have enough red blood cells. Anemia can make you feel weak and tired. Other symptoms include fatigue, dizziness, paleness and a rapid heart rate.

2. You might experience balance issues

Vitamin B12 is also an essential part of a healthy nervous system. Low B12 levels can cause the nerves in your brain, spinal cord, and elsewhere in your body to slowly degenerate.

This is called neuropathy, a condition characterized by impaired nerve function. This causes tingling, numbness, weakness and balance problems. These symptoms may be worse if you also have anemia.

3. You may develop sensory issues and numbness

Myelopathy is damage to the spinal cord. This happens when neurons in a specific part of the spinal cord deteriorate. Neurons are nerve cells that receive and process information by relaying it to other cells.

This leads to muscle weakness, sensory issues, numbness and tingling. This can also cause difficulty detecting light touch and vibration.

People with myelopathy may also experience problems with proprioception, the ability to sense and judge their body position, such as knowing how high they raise an arm without looking.

People with this condition may also experience symptoms resembling neuropathy.

4. Other symptoms

Other symptoms of vitamin B12 deficiency may include:

• Low white blood cell count, which increases your risk of infection
• Low platelet count, which increases your risk of bleeding
• Headaches
• Weight loss
• Mood changes, especially depression
• Behavioral changes
• Walking problems
• Loss or diminished sense of smell
• Swollen tongue

What are the causes of vitamin B12 deficiency?

Insufficient intake

Vitamin B12 is found in various food sources. These include:

• Fish
• Meat
• Milk
• Fortified plant-based foods such as fortified plant milks, nutritional yeast, or cereals

Many sources of vitamin B12 come from animal proteins. For this reason, long-time vegetarians or vegans who do not take vitamin B12 supplements are at risk of vitamin B12 deficiency.

The risk is also higher among older people and people who abuse alcohol.

Impaired absorption

Vitamin B12 is absorbed in the intestine with the help of a protein called intrinsic factor. When the absorption process doesn’t work properly, you can develop a vitamin B12 deficiency.

Causes of impaired B12 absorption include:

• Pernicious anemia, an autoimmune disease in which antibodies attack cells that release intrinsic factor
• Inflammatory gastrointestinal (GI) disorders like Crohn’s disease and celiac disease
• Long-term use of certain medications, such as the diabetes medication metformin and proton pump inhibitors (PPIs) that reduce stomach acid
• Gastric bypass, a bariatric surgery that changes the structure of the stomach
• Gastrointestinal resection surgery, a treatment for serious medical problems like intestinal obstruction or cancer

Why is it difficult to diagnose?

The diagnosis of vitamin B12 is not always easy. Indeed, many of the common symptoms overlap with those of other health conditions. Your medical team may consider several diagnoses besides vitamin B12 deficiency.

Your medical history can help your doctor understand your symptoms. A physical exam can also help identify signs of vitamin B12 deficiency.

For example, a weak, rapid pulse or pale fingers may be a sign of anemia. Signs of neuropathy may include poor sensation in the feet and poor reflexes. These signs can be found in other conditions.

Treatment

Vitamin B12 deficiency can be managed with oral or injectable B12 supplements. If an absorption problem is causing your B12 deficiency, you may need an injection. The injection will help the vitamin be absorbed directly into your bloodstream.

Some patients require lifelong B12 supplementation. This usually depends on the cause of the deficiency. You may need to continue taking B12 supplements even after your symptoms improve.