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13 symptoms of vitamin B12 deficiency

Written by John Davis

Last updated: September 13, 2022

Vitamin B12 deficiency is a condition that occurs when your body is not absorbing vitamin B12 properly or if you’re not getting enough of it in your diet. Deficiency in vitamin B12 or folate can cause a wide range of neurological, psychological, and physical symptoms. However, the good news is that it can be treated through dietary changes or with vitamin B12 supplements or medications. (1)

What is vitamin B12?

Vitamin B12 is a vital nutrient that aids in keeping blood cells and nerves healthy. Additionally, it helps in the production of DNA, the genetic material found in all of our cells. Since the body does not produce vitamin B12 on its own, you must consume a diet rich in vitamin B12 to get it. You can get vitamin B12 by eating and drinking animal products, including meat, dairy, and eggs. It is also found in some fortified foods, which are foods that have additional nutrients and vitamins, such as nutritional yeast and bread. (2)

Adults require about 2.4 mcg (micrograms) of vitamin B12 per day, but breastfeeding and pregnant women need more.

How much vitamin B12 should you get?

The answer is based on your age, eating habits, medical history, current medications, and other factors. (3)

The age-specific average recommended daily doses vary by age:

  • Toddlers (up to 6 months): 0.4 micrograms
  • Babies (7-12 months): 0.5 micrograms
  • Kids (1-3 years): 0.9 micrograms
  • Kids (4-8 years): 1.2 micrograms
  • Kids (9 – 13 years): 1.8 micrograms
  • Teens (14 to 18 years): 2.4 micrograms
  • Adults (19 years and older): 2.4 micrograms
  • Pregnant adults: 2.6 micrograms
  • Breastfeeding mothers: 2.6 micrograms

List of vitamin B12 deficiencies

Let’s look at the signs and symptoms of vitamin B12 deficiency as well as their causes:

1. Paresthesia: Tingling sensation in the hands and/or feet

A deficiency of vitamin B12 can cause tingling or “pins and needles” in the hands or feet. This symptom appears because the vitamin is essential for proper functioning of the nervous system and a lack of it might result in nerve injury or issues with nerve conduction. (4)

Vitamin B-12 aids in the neurological system’s production of myelin. Our nerves are shielded by myelin, which also aids in the transmission of sensations throughout the body.

Vitamin B-12 deficiency may hinder the production of enough myelin to coat the nerves, resulting in nerve damage.

Peripheral nerves, which include the nerves in the hands and feet, are more prone to these issues and may experience tingling due to peripheral nerve injury. (5)

2. Trouble walking

Movement issues may develop over time as a result of peripheral nerve injury brought on by a vitamin B-12 deficiency.

A person may find it difficult to walk unaided if they have numbness in their feet. Additionally, they may experience weakened muscles and slower reflexes. (6)

3. Fatigue

You might experience fatigue if your B12 levels are low or inadequate.

B12 is required for healthy cell function in your body. As a result, low B12 levels can reduce the production of healthy red blood cells, which can diminish oxygen supply in the body.

Keep in mind that megaloblastic anemia can be caused by a deficiency in B12 or folate. This condition can lead to impaired DNA synthesis and the formation of abnormal, immature, and large red blood cells.

You are likely to feel fatigued and weak if your body lacks enough healthy red blood cells to transport oxygen to your tissues. (7)

It’s crucial to understand that even when B12 levels are regarded as normal or borderline low, you might still experience fatigue and other symptoms linked to B12 deficiency.

4. Rapid heart rate

Vitamin B12 deficiency may lead to a faster heart rate.

Your heart may start beating faster to compensate for the body’s decreased supply of healthy red blood cells.

Anemia puts pressure on the heart to pump blood more quickly and in a larger volume around the body. This reaction is the body’s attempt to make sure that enough oxygen gets to all of the organs and circulates throughout the body. (8)

5. Pale skin

Jaundice, or pale or yellow skin, is a common sign of vitamin B-12 insufficiency.

When the body is unable to produce enough healthy red blood cells, jaundice can start to appear. The typical color of the skin is produced by the red blood cells that circulate beneath it. The skin could appear pallid if there aren’t enough of these cells.

Vitamin B-12 aids in the production of healthy red blood cells. Megaloblastic anemia, or a lack of red blood cells, can be brought on by vitamin B-12 deficiency and is often linked to jaundice. (9)

Red blood cells that are weaker due to this type of anemia are subsequently broken down more quickly by the body. Bilirubin is released by the liver during red blood cell breakdown and the brownish pigment known as bilirubin is what causes jaundice’s characteristically yellow tone to the skin. (10)

6. Shortness of breath

A person who has anemia brought on by a vitamin B-12 deficiency could experience some slight breathlessness. This may be related to a rapid heartbeat and a deficiency in healthy red blood cells.

Anyone who has severe respiratory problems should contact a doctor right away. (11)

7. Glossitis: Inflammation and pain in the mouth and tongue

Having a red, sore tongue is referred to as having glossitis in medical terms. It might result from a B12 shortage and it can appear alongside other conditions such as  stomatitis, which is marked by ulcers and inflammation in the mouth and tongue.

Stomatitis and glossitis can occur without anemia and can be a symptom of an early B12 insufficiency, even though they are particularly common in people with anemia caused by a B12 shortage. (12)

It is critical to remember that glossitis can also be caused by other nutrient deficiencies, such as riboflavin (B2), folate, and niacin (B3) deficiencies.

8. Mental impairment and difficulty concentrating

Cognitive impairment is the term used by medical professionals to describe mental issues brought on by issues such as vitamin B-12 deficiency. This condition is characterized by memory loss and difficulty thinking.

Clinical studies have also linked low vitamin B-12 levels have been linked to a higher risk of Alzheimer’s disease, Parkinson’s disease, and vascular dementia. (13)

The low amount of oxygen getting to the brain could be to blame for reasoning and thinking problems.

People with low or inadequate B12 levels may experience mental fogginess, trouble focusing, and difficulties completing ordinary tasks because of the negative effects of B12 deficiency on the central nervous system.

The risk of B12 insufficiency rises with age, and older people are particularly vulnerable to these negative effects.

In fact, a number of studies have linked declining mental health in older people with low vitamin B12 levels. Fortunately, research indicates that B12 supplementation helps relieve mental impairment caused by low B12 levels. (14)

9. Gastrointestinal issues such as diarrhea, nausea, and vomiting

A vitamin B12 deficiency can also result in a variety of gastrointestinal issues, such as diarrhea, nausea, constipation, bloating, and gas.

These problems can affect both children and adults with B12 deficiency. Lack of healthy red blood cells prevents enough oxygen from reaching the intestines. As a result, you may feel ill or even fall ill.

Keep in mind that many of these symptoms are non-specific and may have other causes. For instance, diarrhea may be caused by infections, drugs, and food intolerances. (15)

10. Irritability

A person’s mood may be impacted by a vitamin B12 deficiency, sometimes leading to irritation or sadness.

The relationship between vitamin B-12 and mental health requires further study.  According to one theory, vitamin B-12 aids in the breakdown of a brain chemical known as homocysteine. Homocysteine buildup in the brain can have negative effects on mental health. (16)

11. Loss of appetite and weight loss

A vitamin B-12 deficiency can cause digestive issues, such as nausea, which can make you feel lethargic and reduce your appetite. In the long run, a diminished appetite can result in weight loss. (17)

12. Depressive symptoms

Deficiency in Vitamin B12 can have adverse effects on your mental health because B12 is necessary for the healthy operation of your entire central nervous system.

Vitamin B12 deficiency is linked to a higher risk of depression.

The level of homocysteine, a sulfur-containing amino acid, can be elevated when B12 levels are low. As a result, the body may experience DNA damage, more oxidative stress, and cell death, which could eventually lead to the onset of depression. (18)

A 2020 study of 132 kids and teenagers, 89 of whom had depression and 43 of whom did not, showed that individuals with depression had lower vitamin B12 levels and higher homocysteine levels than those without depression.

Low or insufficient B12 levels can also cause other mental problems, including mood problems and psychosis.

13. Headaches

Headaches are among the most common adverse neurological effects of B12 deficiency and insufficiency.

In fact, both adults and children who are B12 deficient report headaches as one of their most frequent symptoms.

Some clinical studies indicate that individuals with specific forms of headaches are more likely to have vitamin B12 deficiency.

In a 2019 study of 140 adults, 50% of whom had migraines, blood levels of vitamin B12 were found to be considerably lower in participants who experienced migraines compared to participants without migraine history. (19)

Additionally, the study found that individuals with higher B12 levels had an 80% lower risk of developing migraines than those with lower B12 levels.

Other symptoms of vitamin B12 deficiency

In addition to the previously mentioned signs and symptoms, vitamin B12 deficiency may cause:

  • Impotence issues and erectile dysfunction: Due to elevated levels of homocysteine in the body, men with B12 deficiency may have erectile dysfunction.
  • Visual impairment:Vision problems may result from a B12 deficiency, possibly as a result of optic nerve injury.
  • Impaired coordination: B12 insufficiency can result in a neurological condition known as ataxia, or impaired coordination and balance, which As a result, the individual may experience difficulty balancing and walking.
  • Muscle weakness and muscle cramps: Deficiency of B12 impairs sensory and motor nerve function, resulting in cramping and weakening in the muscles. (20)

Causes of vitamin B12 deficiency

A lack of vitamin B12 in your diet or improper vitamin B12 absorption in your body might result in vitamin B12 insufficiency. (21) Pernicious anemia can result from a variety of conditions or ailments, including: (21)

  • Diet: A vitamin B12 deficit can occur if you don’t consume enough foods that are naturally high in the vitamin or foods that have been fortified with it.
  • Gastritis: Gastritis is an inflammation of the gut lining and is a common cause of deficiency in vitamin B12. The lack of hydrochloric acid in your stomach, which is necessary for vitamin B12 absorption, may result in vitamin B12 deficiency.
  • Pernicious anemia: People with this rare medical illness are unable to produce intrinsic factor, a stomach-produced protein. Your body needs intrinsic factor in order to absorb vitamin B12. Those who suffer from pernicious anemia may also suffer from vitamin B12 deficiency.
  • Digestive disorders: Conditions like celiac disease and Crohn’s disease, which impact the digestive tract, can hinder your body from absorbing vitamin B12 properly.
  • Surgery: Individuals who undergo gastrointestinal surgery, such as weight loss surgery (gastric bypass), may experience issues with vitamin B12 absorption.
  • Alcohol use disorder: This illness can harm your digestive tract and result in a deficiency of vitamin B12.
  • Transcobalamin II deficiency: This uncommon genetic condition affects the body’s ability to transport vitamin B12.

Who is at risk for vitamin B12 deficiency?

Vitamin B12 deficiency anemia risk factors include:

  • A history of the illness in the family
  • Type 1 diabetes and other autoimmune diseases.
  • Crohn’s illness
  • Some medications
  • HIV
  • Restrictive diets
  • Being an older adult

Your body requires vitamin B12 in order to function properly. By getting enough vitamin B12 in your diet, you can avoid having a vitamin B12 deficiency. Be sure to make an appointment with your doctor to have a blood test to evaluate your levels if you are at risk of developing a deficiency in vitamin B12 or are already exhibiting deficiency symptoms. (22)


John Davis