Nutrition

How Long To Recover From Vitamin B12 Deficiency? 2025 Updated Answer

by

An estimated 6% of adults[1] under the age of 60 in the United States have vitamin B12 deficiency.[1] For those over the age of 60,[1] the rate is higher, with approximately 20% having a deficiency.

Low vitamin B12 can leave you feeling downright crummy, causing symptoms such as fatigue, difficulty concentrating, and depression.

The good news is that vitamin B12 deficiency can be treated with oral vitamin B12 supplements or intramuscular injections.

So, how long to recover from vitamin B12 deficiency after starting treatment?

This article explores vitamin B12 deficiency, including common symptoms, causes, and treatment options.

How Long To Recover From Vitamin B12 Deficiency?

The amount of time it takes to recover from vitamin B12 deficiency depends on the cause and severity of the deficiency.

With proper treatment, a mild deficiency may be corrected within a few weeks.

However, a severe deficiency may take six months to a year to fully resolve. Prolonged vitamin B12 deficiencies can result in permanent nerve damage.

What Is Vitamin B12?

What Is Vitamin B12?
Vitamin B12 plays a crucial role in the proper functioning of the body.

Vitamin B12, also known as cobalamin, is a water-soluble vitamin that is involved in many important bodily processes,[1] including:

  • The formation of red blood cells, white blood cells, and platelets.
  • Functioning of your nervous system.
  • DNA production.
  • Converting the food you eat into energy.

Unlike many other water-soluble vitamins, the body can store vitamin B12 for years in the liver,[2] with excess being excreted in the urine.

Vitamin B12 is primarily found in animal products, such as:

  • Meat.
  • Fish.
  • Poultry.
  • Eggs.
  • Dairy products.

Fortified foods, such as ready-to-eat breakfast cereals and nutritional yeasts, are plant-based sources of vitamin B12.

Teens over the age of 14 and adults should consume 2.4 micrograms[1] of B12 per day. This number increases to 2.6 micrograms[1] during pregnancy and 2.8 micrograms[1] during lactation.

Symptoms Of Vitamin B12 Deficiency

Your body does not make vitamin B12. If you do not consume enough vitamin B12, you may begin to feel tired and weak. These symptoms are caused by megaloblastic anemia, the hallmark of vitamin B12 deficiency,[3] which is characterized by very large, immature red blood cells and impaired DNA synthesis.

Other symptoms of vitamin B12 deficiency[4] include:

The body can store 1 milligram to 5 milligrams[1] of vitamin B12, so deficiency symptoms may take several years to appear.

What Are The Causes?

A vitamin B12 deficiency occurs when your diet lacks adequate amounts of vitamin B12 or your body has difficulty absorbing the nutrient.

Insufficient Dietary Intake

A diet that includes meat, fish, and dairy products will generally provide adequate vitamin B12. Individuals who do not frequently consume these foods, such as those who follow a vegetarian or vegan diet, are more likely to experience vitamin B12 deficiency.

Impaired Absorption

Certain situations and chronic health conditions that affect your digestive system may make it difficult for your body to absorb vitamin B12. They include:

  • Pernicious anaemia. A condition that occurs when the stomach does not make enough of a protein called intrinsic factor[8] to absorb B12. Intrinsic factor attaches to vitamin B12 and transports it to the intestines to be absorbed. Without intrinsic factors, your body cannot properly absorb vitamin B12.
  • Intestinal problems. Conditions such as Crohn’s disease,[9] celiac disease,[9] and bacterial overgrowth[10] in the small intestine can make it difficult for your body to absorb vitamin B12.
  • Age. Older adults are at a greater risk of vitamin B12 deficiency because of the high prevalence of atrophic gastritis,[11] a condition in which the stomach lining has thinned. In addition, older adults are more likely to have pernicious anemia.
  • Medications. Stomach acid-reducing medications[12] such as proton-pump inhibitors, H2 blockers, and the diabetes medication metformin[13] can interfere with vitamin B12 absorption.
  • Stomach surgeries. Gastric bypass surgery[14] or other surgeries that change the structure of the stomach can reduce the amount of intrinsic factor produced and the amount of space available to absorb vitamin B12.
  • Alcohol consumption. Chronic alcohol consumption[15] can interfere with the absorption and usage of vitamin B12.

Diagnosis

If you suspect a vitamin B12 deficiency, it’s important to consult with a healthcare provider. They will likely recommend laboratory evaluation that includes a complete blood count and serum vitamin B12 levels.

Additionally, your provider will review your medical history and perform a physical examination to help determine the cause of your deficiency.

It’s worth noting that individuals with liver disease, cancer, or a history of alcohol abuse may have falsely elevated vitamin B12. This can occur due to decreased liver clearance[4] of proteins that transport the vitamin.

Vitamin B12 Deficiency Treatments

Vitamin B12 Deficiency Treatments
Treatment for vitamin B12 deficiency involves dietary changes, oral supplementation, or injections.

If a B12 vitamin deficiency is confirmed, seek treatment immediately. Vitamin B12 deficiency can be treated with oral vitamin B12 dietary supplements or injections.

Vitamin B complex or B12 supplements can help improve vitamin B12 levels when a deficiency is due to an insufficient dietary intake. Incorporating more fortified foods rich in vitamin B12 is also generally recommended.

However, if the underlying cause of deficiency is caused by poor absorption due to a lack of intrinsic factors or stomach surgery, vitamin B12 injections administered into the muscle are considered to be the only effective mode of repletion.

If B12 injections are necessary, you may receive one every day for the first week of treatment.[16] As your red blood cells return to normal, you will probably receive a B12 injection every other day for two weeks and then every three to four days for up to three weeks.

Depending on the cause of the deficiency, you may need lifelong B12 injections. These are generally administered every month.

The amount of time it takes for symptoms to resolve depends on the severity of your deficiency. Neurological symptoms[17] generally begin to improve within the first week of treatment and are often resolved within six months of treatment. However, it may take up to a year to fully recover.

A prolonged vitamin B12 deficiency[18] can lead to permanent, irreversible neurological damage.

The Bottom Line

Vitamin B12 is a water-soluble vitamin that is crucial for maintaining a healthy life. It plays an important role in the formation of healthy red blood cells, the functioning of the nervous system, DNA production, and converting food into energy.

Vitamin B12 deficiency is often caused by insufficient dietary intake or malabsorption due to certain health conditions, medications, and stomach surgeries.

If you are showing signs or symptoms of a vitamin B12 deficiency, it is important to visit a healthcare provider for proper diagnosis and treatment. Treatment for vitamin B12 deficiency involves dietary changes, oral supplementation, or injections.

Depending on the cause and severity of the deficiency, full recovery can take anywhere from several months to a year. If your deficiency is caused by absorption issues, you may require lifelong vitamin B12 injections to maintain optimal health.

+ 18 Sources

  1. Nih.gov. (2016). Office of Dietary Supplements – Vitamin B12. [online] Available at: https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/.
  2. Medlineplus.gov. (2022). Vitamin B12: MedlinePlus Medical Encyclopedia. [online] Available at: https://medlineplus.gov/ency/article/002403.htm.
  3. Nih.gov. (2023). Office of Dietary Supplements – Vitamin B12. [online] Available at: https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/.
  4. Langan RC;Goodbred AJ (2017). Vitamin B12 Deficiency: Recognition and Management. American family physician, [online] 96(6). Available at: https://pubmed.ncbi.nlm.nih.gov/28925645/.
  5. Pun Narayan Shrestha, Bipin Khanal and Joshi, P. (2021). Chronic Diarrhoea: A Rare Presentation Of Vitamin B12 Deficiency Anemia In Children. [online] ResearchGate. Available at: https://www.researchgate.net/publication/367825010_Chronic_Diarrhoea_A_Rare_Presentation_Of_Vitamin_B12_Deficiency_Anemia_In_Children.
  6. Pelling, M.M., Kimura, S.T., Han, E.J. and Yoo Mee Shin (2022). Severe Vitamin B12 Deficiency Presenting as Pancytopenia, Hemolytic Anemia, and Paresthesia: Could Your B12 Be Any Lower? Cureus. [online] doi:https://doi.org/10.7759/cureus.29225.
  7. Sveta Aghayeva, Yavuz Emre Sükür, Aslan, B. and Murat Sonmezer (2022). THE ASSOCIATION BETWEEN SERUM THYROID HORMONE, VITAMIN D, VITAMIN B12, FOLATE, FERRITIN, AND ZINC LEVELS… [online] ResearchGate. Available at: https://www.researchgate.net/publication/364701434_THE_ASSOCIATION_BETWEEN_SERUM_THYROID_HORMONE_VITAMIN_D_VITAMIN_B12_FOLATE_FERRITIN_AND_ZINC_LEVELS_AND_FEMALE_INFERTILITY_A_COMPASSION_WITH_HEALTHY_PREGNANT_SUBJECTS.
  8. Joshua William Miller and Green, R. (2020). Assessing vitamin B-12 absorption and bioavailability: read the label. The American Journal of Clinical Nutrition, [online] 112(6), pp.1420–1421. doi:https://doi.org/10.1093/ajcn/nqaa271.
  9. Medlineplus.gov. (2023). Vitamin B Test. [online] Available at: https://medlineplus.gov/lab-tests/vitamin-b-test/.
  10. Wexler, A.G., Schofield, W.B., Degnan, P.H., Folta-Stogniew, E., Barry, N.A. and Goodman, A.L. (2018). Human gut Bacteroides capture vitamin B12 via cell surface-exposed lipoproteins. eLife, [online] 7. doi:https://doi.org/10.7554/elife.37138.
  11. Wong, C. (2015). Vitamin B12 deficiency in the elderly: is it worth screening? Hong Kong Medical Journal. [online] doi:https://doi.org/10.12809/hkmj144383.
  12. Miller, J.W. (2018). Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications. Advances in Nutrition, [online] 9(4), pp.511S518S. doi:https://doi.org/10.1093/advances/nmy023.
  13. Kim, J., Chul Woo Ahn, Fang, S., Hye Sun Lee and Jong Suk Park (2019). Association between metformin dose and vitamin B12 deficiency in patients with type 2 diabetes. Medicine, [online] 98(46), pp.e17918–e17918. doi:https://doi.org/10.1097/md.0000000000017918.
  14. Amna Al Mansoori, Shakoor, H., Ali, H.I., Feehan, J., Al, A.S., Leila Cheikh Ismail, Marijan Bosevski, Apostolopoulos, V. and Stojanovska, L. (2021). The Effects of Bariatric Surgery on Vitamin B Status and Mental Health. Nutrients, [online] 13(4), pp.1383–1383. doi:https://doi.org/10.3390/nu13041383.
  15. Gana, W., Arnaud De Luca, Debacq, C., Poitau, F., Poupin, P., Aidoud, A. and Bertrand Fougère (2021). Analysis of the Impact of Selected Vitamins Deficiencies on the Risk of Disability in Older People. Nutrients, [online] 13(9), pp.3163–3163. doi:https://doi.org/10.3390/nu13093163.
  16. Medlineplus.gov. (2024). Cyanocobalamin Injection: MedlinePlus Drug Information. [online] Available at: https://medlineplus.gov/druginfo/meds/a605007.html.
  17. Dissanayake Mudiyanselage Priyantha Udaya Kumara Ralapanawa, Kushalee Poornima Jayawickreme, Ekanayake and Widana Arachchilage Thilak Ananda Jayalath (2015). B12 deficiency with neurological manifestations in the absence of anaemia. BMC Research Notes, [online] 8(1). doi:https://doi.org/10.1186/s13104-015-1437-9.
  18. Pinar Arican, Bozkurt, O., Dilek Cavusoglu, Pinar Gencpinar, Senay Haspolat, Duman, O. and Nihal Olgac Dundar (2020). Various neurological symptoms with vitamin B12 deficiency and posttreatment evaluation. Journal of Pediatric Neurosciences, [online] 15(4), pp.365–365. doi:https://doi.org/10.4103/jpn.jpn_130_19.