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Vitamin B12 is an essential nutrient that helps your body make red blood cells and DNA—the genetic material in all your cells and keeps your nerve cells and blood cells healthy. Because your body doesn’t make it naturally, you must get vitamin B12 through food or supplements. Vitamin B12 (also called cobalamin) is found mainly in animal products like meat, fish, poultry, eggs, and dairy. It’s also added to fortified foods such as certain cereals, nutritional yeast, and plant milks. Adults need about 2.4 micrograms (mcg) daily; pregnant or breastfeeding women and growing children need more.

How Does the Body Absorb Vitamin B12?

Two main steps are required for absorption:

1. Hydrochloric acid in the stomach separates vitamin B12 from food.

2. The vitamin then binds with intrinsic factor, a protein made by the stomach, which allows it to be absorbed into the bloodstream.

If either step is disrupted, a vitamin B12 deficiency can occur.

What Is Vitamin B12 Deficiency?

Vitamin B12 deficiency happens when your body doesn’t get or can’t absorb enough vitamin B12 from food. This leads to low levels of healthy red blood cells and can cause physical, neurological, and psychological problems if untreated.

Vitamin B12 deficiency anaemia occurs when a lack of vitamin B12 prevents the body from making enough healthy red blood cells. Without sufficient B12, red blood cells become large and irregular, leading to fatigue and weakness. However, some people can have vitamin B12 deficiency without developing anaemia.

Anyone can develop vitamin B12 deficiency, but it’s more common in people over age 60. Around 1.5% to 15% of people are affected:

• At least 3% of adults aged 20–39
• 4% of adults aged 40–59
• 6% or more of adults aged 60 and over

What causes Vitamin B12 Deficiency?

Deficiency can result from either a lack of intake or poor absorption. Common causes include:

• Low dietary intake: People who eat few or no animal products, or unfortified foods.
• Gastritis: Inflammation of the stomach lining can reduce stomach acid needed for absorption.
• Pernicious anaemia: A rare autoimmune disease where the stomach doesn’t make intrinsic factor, preventing absorption.
• Digestive diseases: Conditions such as Crohn’s disease or celiac disease interfere with nutrient absorption.
• Surgery: Gastrointestinal surgeries, such as gastric bypass, can affect absorption.
• Alcohol use disorder: Alcohol damages the stomach lining and reduces absorption.
• Genetic disorders: Rare conditions like Transcobalamin II deficiency impair B12 transport within the body.

In some cases, low B12 levels may even mask or mimic symptoms that resemble a sign of cancer, such as fatigue, weight loss, or pale skin.

Symptoms of Vitamin B12 Deficiency

Symptoms may appear slowly and worsen over time. Some people show no signs despite low levels.

Some common symptoms may include:

• Fatigue or weakness
• Nausea, vomiting, or diarrhoea
• Loss of appetite and weight loss
• Sore tongue or mouth
• Pale or yellowish skin
• Numbness or tingling in hands and feet
• Trouble walking, balancing, or speaking
• Vision problems
• Memory issues or confusion
• Depression, irritability, or personality changes

Diagnosis

Because symptoms can mimic other conditions, vitamin B12 deficiency can be difficult to diagnose. Healthcare providers will usually advise a blood test to confirm levels of vitamin B12 in the blood. The results from these tests can help to guide next steps and treatment.

If your provider suspects absorption problems, additional tests for intrinsic factor antibodies or methylmalonic acid (MMA) may be ordered.

Treatment for Vitamin B12 Deficiency

If test results show low B12 levels treatment is typically straightforward and effective. Options include:

1. Oral B12 supplements (daily or weekly)

2. High-dose B12 tablets

3. B12 injections

For faster absorption, especially in those with gut absorption issues. Hydroxocobalamin injections are the most common and are a longer acting natural form of vitamin B12.

Vitamin B12 Injection Side Effects:
Generally, injections are safe, but mild side effects can occur, such as:

• Pain, redness, or swelling at the injection site
• Mild diarrhea or nausea
• Dizziness or headache
• Rare allergic reaction

If you experience chest pain, difficulty breathing, or hives after a Vitamin B12 injection, seek medical attention immediately.

4. Dietary guidance on fortified foods and lifestyle choices

If vitamin B12 deficiency is diagnosed and treated early, most symptoms improve or disappear.

Complications of Untreated Vitamin B12 Deficiency

An untreated vitamin B12 deficiency can lead to:

• Permanent nerve damage
• Difficulty walking or coordinating movements
• Cognitive impairment or dementia-like symptoms
• Severe anaemia and heart strain
• Infertility (reversible with treatment)

In rare cases, chronic deficiency may mask or mimic symptoms that could otherwise indicate a sign of cancer, delaying early diagnosis of other conditions.

Prevention

You can usually prevent vitamin B12 deficiency by maintaining a balanced diet and managing underlying health conditions.

Sources of Vitamin B12:

• Animal products: Red meat, poultry, fish, eggs, milk, and dairy
• Fortified foods: Certain cereals, plant milks, nutritional yeast, and bread (check nutrition labels)
• Supplements: Many multivitamins include B12; standalone B12 supplements are also available. Ask your healthcare provider which type and dosage are best for you.

Additional Prevention Tips:

• Limit alcohol intake to protect your digestive system.
• Follow your doctor’s advice if you have gastrointestinal or autoimmune disorders.
• Older adults and people on certain medications should get their B12 levels checked regularly.

Vitamin B12 is vital for maintaining healthy nerves, blood cells, and brain function. Deficiency can cause serious complications if untreated, but it’s highly manageable with early detection and proper treatment. Vitamin B12 injections, including Hydroxocobalamin injections, are effective in restoring normal levels, though mild Vitamin B12 injection side effects may occur. Maintaining a diet rich in B12 or fortified foods, managing medical conditions, and monitoring your levels can help prevent deficiency and protect your long-term health.

A vitamin B12 blood test can be the first step in taking charge of your health. Many healthcare providers and private clinics, Like Fusion Healthcare in Luton, can provide timely appointments and results.