Vitamin B12 Deficiencies

Vitamin B12 Deficiencies Unveiled: Symptoms & Solutions

Vitamin B12 Deficiencies Unveiled: Symptoms & Solutions

Discover the signs and solutions for Vitamin B12 Deficiencies. Learn how to regain energy and vitality with expert advice.


Vitamin B12 deficiencies are a common issue that can affect people of all ages. Vitamin B12 stands as a critical nutrient, pivotal in numerous facets of well-being, including DNA synthesis, nerve function, and red blood cell formation. Vitamin B12 deficiencies can cause a wide range of symptoms, some mild and some more serious if left untreated. Fortunately, vitamin B12 deficiencies are usually easy to detect and simple to correct through diet and supplementation.

What is Vitamin B12?


Vitamin B12 deficiencies are a lack of vitamin B12 in the body. Cobalamin, or Vitamin B12, is a water-soluble vitamin found naturally in certain foods and offered in supplement form. It helps keep the body’s nerves and blood cells healthy and helps make DNA.

Vitamin B12 is unique because it contains the mineral cobalt, which gives the vitamin its chemical name, cobalamin. There are several forms of vitamin B12 in supplements, including cyanocobalamin, methylcobalamin, and adenosylcobalamin.

The recommended daily intake of vitamin B12 is 2.4 mcg for adults, 2.6 mcg for pregnant women, and 2.8 mcg for lactating women. Vitamin B12 is found naturally in meat, fish, eggs, and dairy products. It can also be taken as a supplement, either in pill form or as a sublingual (under the tongue) tablet.

Causes of Vitamin B12 Deficiency


There are several potential causes for vitamin B12 deficiencies:

  • Insufficient Intrinsic Factor– Produced by stomach cells, this protein is crucial for the absorption of Vitamin B12.. Certain conditions such as pernicious anemia, gastric surgery, or inflammation can reduce intrinsic factors.
  • Inadequate Intake – Vegans, vegetarians, and elderly adults are at risk for B12 deficiency if they do not eat fortified foods or take supplements. Studies show over 15% of adults over age 60 are deficient in B12.
  • Malabsorption Syndromes – Gastrointestinal conditions that affect absorption like celiac disease, Crohn’s disease, inflammatory bowel disease, and leaky gut syndrome can interfere with B12 absorption.
  • Acid Reducers – Long-term use of medicines that reduce stomach acid such as proton pump inhibitors and H2 blockers are linked to B12 deficiency.
  • Other Medications – Metformin, a popular diabetes drug, can impair B12 absorption and increase risk of deficiency when taken long term.

Symptoms of Vitamin B12 Deficiency

Vitamin B12 deficiencies can cause a wide spectrum of symptoms. Some people may not have symptoms in the early stages of B12 deficiency. Symptoms tend to develop gradually over time and can be vague and easily overlooked. Here are some common symptoms of low B12 levels:

  • Fatigue and weakness
  • Lightheadedness or dizziness
  • Heart palpitations or rapid heartbeat
  • Shortness of breath or chest pain with exertion
  • Nausea or poor appetite
  • Constipation, diarrhea, or abdominal cramping
  • Pale skin or jaundice
  • Poor concentration, memory loss, or mood changes
  • Numbness or tingling in the hands and feet
  • Balance problems or difficulty walking
  • Depression or confusion
  • Sore mouth or tongue

Prolonged vitamin B12 deficiency can lead to serious neurological complications like dementia, paranoia, delusions, and psychoses if not treated. Anemia is another common complication of low B12 levels.

Diagnosing B12 Deficiency

Doctors can run blood tests to check levels of vitamin B12 along with other indicators of deficiency like homocysteine and methylmalonic acid.

  • Vitamin B12 blood levels below 200 pg/mL indicate a vitamin B12 deficiency. Levels between 200-350 pg/mL are considered borderline low.
  • High homocysteine levels can signify a B12 deficiency. Ideal levels are between 5-15 micromole/L.
  • Elevated MMA levels (greater than 0.4 micromole/L) can also indicate insufficient B12.

Doctors look for symptoms of deficiency along with abnormal blood test results to diagnose vitamin B12 deficiency. They may examine the blood under a microscope for enlarged, oddly shaped red blood cells caused by B12 deficiency anemia.

In some cases, doctors may analyze gastric juices or do a small bowel biopsy during endoscopy to check for proper absorption of B12.

Treating Vitamin B12 Deficiency

The good news is that vitamin B12 deficiencies are usually simple to treat. Treatment typically involves vitamin B12 injections or high-dose B12 supplements taken by mouth:

  • B12 injections – These bypass potential absorption issues and are required initially for faster recovery in cases of pernicious anemia and severe neurological symptoms. Most people need weekly injections for 1-2 months to replenish B12, then monthly injections for maintenance.
  • High-dose B12 supplements – Oral supplements of at least 1000 mcg per day of B12 can also be used, especially for mild deficiencies without neurological symptoms. Sublingual tablets that are absorbed under the tongue are preferable to pills that must go through the digestive tract. Supplements may be needed for a lifelong life for those with absorption disorders.

Dietary sources of B12 are not adequate for correcting deficiency once it occurs. However, eating B12-rich foods can help prevent recurrent deficiency after treatment. Food sources include beef liver, wild-caught fish, eggs, dairy products, fortified plant milk, and breakfast cereals.

People with absorption issues may need B12 supplements indefinitely even after correcting deficiency to prevent recurrence. Doctors monitor blood levels of B12 and homocysteine to ensure the deficiency is resolved with treatment.

Vitamin B12 Rich Foods

  • Beef liver – 1 oz contains 561 mcg B12 (23,375% DV)
  • Clams – 3 oz contains 84.1 mcg B12 (3,505% DV)
  • Wild-caught salmon – 4 oz contains 4.8 mcg B12 (200% DV)
  • Tuna fish – 3 oz contains 2.5 mcg B12 (104% DV)
  • Nutritional yeast – 1 Tbsp contains 2.4 mcg B12 (100% DV)
  • Grass-fed beef – 4 oz contains 1.4 mcg B12 (58% DV)
  • Eggs – 1 large egg contains 0.6 mcg B12 (25% DV)
  • Milk – 1 cup contains 1.2 mcg B12 (50% DV)
  • Cottage cheese – 1 cup contains 0.9 mcg B12 (38% DV)
  • Fortified plant milk – 1 cup contains 1.2-2.4 mcg B12 (50-100% DV)
  • Fortified cereals – 1 serving contains 1.5-6 mcg B12 (63-250% DV)

The daily Value (DV) for vitamin B12 is 2.4 mcg. Foods providing at least 20% DV per serving are considered high sources of B12. Beef liver, clams, and salmon are the foods highest in bioavailable vitamin B12.

Preventing Vitamin B12 Deficiencies

You can take some proactive steps to help prevent vitamin B12 deficiencies:

  • If you are over 50, vegan/vegetarian or have digestive disorders, ask your doctor to check your B12 status.
  • Consider taking a B12 supplement as a preventive measure if you are at higher risk of deficiency.
  • Eat B12-containing foods like meat, eggs, dairy and fortified foods regularly.
  • If you take acid reducers, have your B12 level monitored since these drugs can reduce B12 absorption.
  • Be aware of medication interactions – speak to your doctor about monitoring B12 levels if you take metformin for diabetes.
  • Get tested sooner rather than later if you have any concerning neurological, psychiatric, blood or gastrointestinal symptoms.

Frequently asked questions about Vitamin B12 deficiencies

What happens when your vitamin B12 is low?

When vitamin B12 levels get too low, it can cause problems with the body’s ability to make new red blood cells and keep nerves healthy. You may feel exhausted and weak. Some people get numbness or tingling in their hands and feet. In severe cases, very low B12 can cause memory problems, depression, and trouble thinking clearly.

How can I raise my B12 levels fast?

The quickest way is to get B12 injections from your doctor. These deliver high amounts of B12 directly into your blood, so you don’t have to absorb it through your digestive system. After some initial shots, your doctor can advise if you need periodic injections to keep your levels up. Taking high-dose B12 supplements by mouth can also help improve levels faster than diet alone.

Is B12 deficiency a serious condition?

It can be serious if it’s not treated. Prolonged B12 deficiency can lead to anemia and permanent nerve damage. But the good news is it’s easy to treat, and most symptoms should improve once your B12 levels are back to normal. Getting diagnosed quickly and getting your levels up prevents lasting complications.

What causes B12 deficiency in adults?

The most common reasons adults become B12 deficient are:

  • Not getting enough B12 from the diet, like in strict vegans/vegetarians
  • Problems absorbing B12, often from low stomach acid or digestive disorders like Crohn’s disease
  • Medications that interfere with B12 absorption, like acid reducers and Metformin
  • A lack of intrinsic factors needed to absorb B12 because of conditions like pernicious anemia

The key is having your B12 level checked if you have any deficiency symptoms and addressing the underlying cause, whether it’s diet, absorption issues, or medication side effects.


In summary, vitamin B12 deficiencies are often because of inadequate intake or absorption issues and cause a variety of symptoms, including fatigue, neurological problems, and anemia. While low B12 can be serious if undetected, the news is its one of the easiest deficiencies to treat. With prompt diagnosis and proper treatment, the symptoms of B12 deficiency can be reversed. Getting enough vitamin B12 from diet, supplements, and injections can usually resolve any deficiencies and prevent complications.

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