Vitamin B12 Deficiency: Signs, Causes, Dosage, and Treatment

Vitamin B₁₂, also called cobalamin, is a water-soluble vitamin. It is one of the eight vitamins that together constitute the vitamin B complex.

Even though you may not hear much about it, vitamin B₁₂ deficiency is far more common than most healthcare practitioners and the general public realize.

According to a review published in the American Journal of Clinical Nutrition, vitamin B₁₂ deficiency and depletion are common in wealthier countries, particularly among the elderly, and are also prevalent in younger populations in developing countries around the world.^[1]

In fact, the review article states that approximately 6 percent of people aged 60 or older in the United Kingdom and the United States are vitamin B₁₂ deficient and 20 percent of this population is considered to have a marginal status of B₁₂.

Why is Vitamin B₁₂ Important?

Vitamin B₁₂ is vital for the formation of red blood cells (RBCs) that carry oxygen around the body. It is also needed for the proper functioning and health of nerve tissue, as it is involved in producing the protective myelin sheath that covers the nerves and conducts nerve impulses.

It works together with folate in the metabolism of cells, DNA synthesis, and the metabolism of fatty and amino acids.

This particular B vitamin also helps our bodies absorb folic acid, which facilitates the release of energy.

Because your body doesn’t make vitamin B₁₂ on its own, it is important to get it from food sources (especially animal-based foods) or supplements on a regular basis. In order to avoid any undue complication, it is always recommended to consult your doctor before starting any supplement regimen.

How Much Vitamin B₁₂ Do I Need?

According to the National Institutes of Health (NIH), the daily requirement of B₁₂ varies across different age groups and often according to individual needs.

This vitamin along with folic acid is particularly important during pregnancy, as this nutritional duo is known to prevent birth defects related to the central nervous system (CNS) as well as preterm delivery.

Vitamin B₁₂ is essential for normal cell division and differentiation; thus, it has a crucial role in the proper and timely development of the CNS in babies.

Pregnant women’s recommended daily intake (RDI) of vitamin B₁₂ stands at 2.6 mcg, which is relatively higher than that of the general population to accommodate the additional need of B₁₂ for the growing fetus.

The RDI for this vitamin is still higher for nursing women who must supply adequate B₁₂ to their growing infants through breast milk. If the baby does not get adequate B₁₂, it is likely to suffer from developmental delays, loss of appetite, and general irritability.

Every breastfeeding woman is advised to maintain a daily intake of 2.8 mcg of B₁₂ to meet both her own and her baby’s nutritional needs.^[2]

What Causes Vitamin B₁₂ Deficiency?

A deficiency of this important vitamin can occur due to a diet that contains very little vitamin B₁₂. People who follow a vegan or vegetarian diet can lack this vitamin because it is commonly found in animal products. Therefore, vegetarians and vegans may need a B₁₂ supplement or make eating foods fortified with B₁₂ a priority.

Another common cause of vitamin B₁₂ deficiency is pernicious anemia.

Pernicious anemia can be from an autoimmune disorder that occurs due to loss of stomach cells that make Intrinsic Factor (IF), a protein that helps the body absorb vitamin B₁₂ in the intestine. This leads to a low vitamin B₁₂ level in the body. Low IF levels can also result from certain medical conditions, medications, and aging.

Another cause of pernicious anemia can be malabsorption in the intestines or a diet deficient in B₁₂.

Who is at a Higher Risk?

• People aged 50 or older
• People who eat a vegetarian or vegan diet
• Infants who are born to vegan mothers and exclusively breastfed
• People suffering from diseases that affect digestion, such as celiac and Crohn’s diseases
• People who have had gastrointestinal surgery
• People who are malnourished
• People who are chronic alcoholics

Vitamin B₁₂ Deficiency Signs and Symptoms

Here are 10 signs that you must look out for in order to identify a vitamin B₁₂ deficiency.

1. Fatigue and Low Energy

Because vitamin B₁₂ plays a prominent role in energy metabolism, its deficiency tends to have a direct impact on your energy and endurance levels.^[3]

Vitamin B₁₂ is needed to form healthy RBCs that carry oxygen to the whole body. Without proper oxygen levels, you feel tired and lethargic, which is what happens when your body doesn’t have sufficient vitamin B₁₂ to produce enough RBCs to do the job. Without oxygen, your muscles have a hard time moving.

Plus, B₁₂ is needed to turn the food you eat into energy to power your metabolism. Low metabolism prevents you from feeling your best and performing at your highest energy level.

2. Numbness and Tingling Sensations

Vitamin B₁₂ plays a key role in keeping your nervous system healthy as it helps with nerve regeneration. Thus, its deficiency is often indicated by neurological symptoms such as numbness and a tingling sensation in the hands and feet.^[4][5]

This vital nutrient also helps with the production of RBCs and thereby facilitates adequate oxygen supply to different parts of the body. The numbness and tingling often associated with low levels of vitamin B₁₂ can also be traced back to a lack of oxygen in the body.

When the body has insufficient vitamin B₁₂, the RBCs formed are larger and irregularly shaped unlike the typical small and round healthy ones. This structural anomaly makes it difficult for the RBCs to move from the bone marrow where they are synthesized into the bloodstream.

As a result, the blood lacks enough RBCs to carry oxygen to vital organs. This kind of deficiency can also disrupt your body’s sense of balance.

3. Low Blood Pressure

Deficiencies of vitamin B₁₂ and folic acid can cause anemia, or an insufficient RBC count. This could lead to low blood pressure, also known as hypotension.

Vitamin B₁₂ helps your body produce RBCs so that adequate oxygen reaches each and every part of your body, including the heart.

A 2012 study published in the Texas Heart Institute Journal reports that vitamin B₁₂ deficiency is well known among neurologists but is often overlooked by cardiologists when treating low blood pressure.^[6]

If you suffer from low blood pressure, opt for a B₁₂ test. Even moderate forms of low blood pressure can cause shortness of breath, dizziness, weakness, fainting, and risk of injury from falls.

4. Skin Lesions

A low level of vitamin B₁₂ can also cause skin lesions and hair changes.

A study published in the Canadian Family Physician reports that vitamin B₁₂ deficiency is linked to skin lesions.^[7]

Unexplained and nonresolving skin lesions can signal vitamin B₁₂ deficiency and necessitate the need for prompt medical attention.

Along with skin lesions, its deficiency can cause hyperpigmentation of the skin, which leads to uneven skin color and dark patches on the skin.

5. Depression

B₁₂ helps lower the level of homocysteine, a by-product of protein metabolism.

A 2017 study found that both depression and anxiety were associated with elevated blood homocysteine levels in older boys

According to a study published in the Journal of Clinical Psychiatry, it is important to consider the possibility of a B₁₂ deficiency among the elderly who are suffering from depression.^[8]

A study published in the Open Neurology Journal shed light on the importance of vitamin B₁₂ supplementation in the treatment of major depressive disorder.^[9]

The study found that people with depression experienced significant improvement in signs and symptoms when treated with vitamin B₁₂ supplementation as well as antidepressants.

6. Cognitive Decline

Low vitamin B₁₂ levels may be the reason behind poor memory and cognitive decline.

Vitamin B₁₂ allows brain cells to form new connections, a process that allows memory formation.^[10]

Plus, it is a vital component of myelin, the coating that protects many brain cells. This is why its deficiency can lead to serious nerve damage and deterioration of brain functioning.

A study published in International Psychogeriatrics suggests that low serum vitamin B₁₂ levels are associated with neurodegenerative disease and cognitive impairment.^[11] This type of dementia is different from Alzheimer’s disease; hence, it needs to be differentiated through a comprehensive neuropsychological evaluation.

Another 2011 study published in Neurology reports that people with low blood levels of vitamin B₁₂ markers may be more likely to have lower brain volumes and experience problems with thinking skills.^[12]

7. Hypothyroidism

Vitamin B₁₂ deficiency is linked to an underactive thyroid gland, also known as hypothyroidism.

The thyroid gland needs a variety of nutrients to produce hormones that regulate many of the body’s functions. Vitamin B₁₂ is one of these nutrients.

A study published in the Journal of the Pakistan Medical Association reports that vitamin B₁₂ deficiency is common in primary hypothyroidism. Supplementation leads to an improvement in symptoms.^[13] The study emphasized screening for vitamin B₁₂ levels in all hypothyroid patients, irrespective of their thyroid antibody status.

8. Infertility

Vitamin B₁₂ deficiency can affect both male and female fertility.

A study published in the Journal of Reproductive Medicine reports that vitamin B₁₂ deficiency is linked to infertility and recurrent miscarriages.^[14]

The study explains that hypercoagulability due to raised homocysteine levels may lead to fetal loss during the initial stage of vitamin B₁₂ deficiency.

More prolonged deficiency may cause changes in ovulation or development of the ovum or changes leading to defective implantation and ultimately infertility.

This vitamin deficiency not only makes it difficult to conceive but also makes it hard to carry the baby to full term.^[15]

If you are having issues with infertility, discuss with your doctor a B₁₂ test to determine if this is a factor for you.

Tips to Fix Vitamin B₁₂ Deficiency

If you think you have symptoms of vitamin B₁₂ deficiency, you can ask your doctor for a blood test. To correct a deficiency, you can do the following:

• Eat foods high in vitamin B₁₂, such as fish, shellfish, meat (especially liver), eggs, milk, and milk products.
• Those who do not eat animal-based products can try foods fortified with B₁₂, such as breakfast cereals, soy products, energy bars, and nutritional yeast. As the risk for a B₁₂ deficiency is much higher if you eat a vegetarian or vegan diet, get a B₁₂ test on a regular basis.
• Those who take medications for diabetes or acid reflux must also opt for a B₁₂ test, as some of these medications can interfere with healthy B₁₂ levels by lowering Intrinsic Factor (IF) in the gut.
• You can opt to take supplements in pill or injection forms. If B₁₂ levels are low from IF problems, injections or sublingual B₁₂ may be a better option. Be sure to consult your doctor, as supplements can interfere with certain medications and hamper their effectiveness.

When to See Your Doctor

If you experience any of the characteristic symptoms of a B₁₂ deficiency, consult your healthcare provider for a proper diagnosis.

The doctor will take into account your signs and symptoms and order a blood test to conclusively determine if you are indeed running low on this vital nutrient. The same procedure is followed in the case of a folate deficiency.

Given that vitamin B₁₂ or folate-deficiency anemia can end up causing some irreversible damage, it is important to address these conditions with a sense of urgency.

If the deficiency is caught early and followed by prompt and appropriate treatment, the signs and symptoms will improve gradually without any long-term or permanent complications. If you suspect any signs and symptoms you have may be from a B₁₂ deficiency, speak with your doctor to get a blood test done.

Resources:

1. Allen LH. How common is vitamin B-12 deficiency? OUP Academic. https://academic.oup.com/ajcn/article/89/2/693S/4596795. Published December 30, 2008.
2. Office of Dietary Supplements – Vitamin B12. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Published November 19, 2018.
3. Huijts M, Duits A, Staals J, van Oostenbrugge RJ. Association of vitamin B12 deficiency with fatigue and depression after lacunar stroke. PloS one. https://www.ncbi.nlm.nih.gov/pubmed/22276208. Published January 20, 2012.
4. Munganda H. NUMB HAND SYNDROME—-A VITAMIN B12 DEFICIENCY. IOSR Journal of Dental and Medical Sciences. https://www.researchgate.net/publication/318530452. Published July 2017.
5. What is Vitamin B12 Deficiency Anemia? Johns Hopkins Medicine Health Library. https://www.hopkinsmedicine.org/healthlibrary/conditions/hematology_and_blood_disorders/anemia_of_b12_deficiency_pernicious_anemia_85,p00080.
6. Ganjehei L, Massumi A, Razavi M, Wilson JM. Orthostatic hypotension as a manifestation of vitamin B12 deficiency. Texas Heart Institute journal. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461697/. Published 2012.
7. Kannan R, Ng MJM. Cutaneous lesions and vitamin B12 deficiency: an often-forgotten link. Canadian family physician Medecin de famille canadien. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2294086/. Published April 2008.
8. Hanna S, Lachover L, Rajarethinam RP. Vitamin b₁₂ deficiency and depression in the elderly: review and case report. Primary care companion to the Journal of clinical psychiatry. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781043/. Published 2009.
9. Syed EU, Wasay M, Awan S. Vitamin B12 supplementation in treating major depressive disorder: a randomized controlled trial. The open neurology journal. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856388/. Published November 15, 2013.
10. Agarwal R. Vitamin B₁₂ deficiency & cognitive impairment in elderly population. The Indian journal of medical research. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237236/. Published October 2011.
11. Moore EM, Mander A, Carne R. Cognitive impairment and vitamin B12: A review. International Psychogeriatrics. https://www.researchgate.net/publication/236834898_Cognitive_impairment_and_vitamin_B12_A_review. Published May 2012.
12. Low vitamin B12 link to brain shrinkage and cognitive problems. Alzheimer’s Research UK. https://www.alzheimersresearchuk.org/low-vitamin-b12-link-to-brain-shrinkage-and-cognitive-problems/. Published September 26, 2011.
13. Jabbar A, Yawar A, Waseem S, et al. Vitamin B12 deficiency common in primary hypothyroidism. JPMA. The Journal of the Pakistan Medical Association. https://www.ncbi.nlm.nih.gov/pubmed/18655403. Published May 2008.
14. Bennett M. Vitamin B12 deficiency, infertility and recurrent fetal loss. The Journal of reproductive medicine. https://www.ncbi.nlm.nih.gov/pubmed/11304860. Published March 2001.
15. Kharb S, Singh A, Bala J. Prospective study on role of folic acid and vitamin B12 in early pregnancy and spontaneous abortion. Biomedical and Biotechnology Research Journal (BBRJ) Biomedical and Biotechnology Research Journal (BBRJ). http://www.bmbtrj.org/article.asp?issn=2588-9834;year=2018;volume=2;issue=4;spage=265;epage=268;aulast=Kharb. Published 2018.