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Could Vitamin B-12 Help Your Hypothyroidism Symptoms?

Are low Vitamin B-12 levels making your Hashimoto’s and hypothyroidism symptoms worse?
Could Vitamin B-12 Help Your Hypothyroidism Symptoms?
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Vitamin B-12 is an essential nutrient that plays a vital role in the body’s energy, nervous system, brain function, and immune system. What is the connection between B-12 and thyroid function? And could a deficiency in this crucial vitamin contribute to your Hashimoto’s and hypothyroidism symptoms? Ahead, a look at the all-important link between your thyroid and Vitamin B-12.

About vitamin B-12

Vitamin B12, also known as cobalamin, is an essential nutrient that plays several vital roles in the body.

Vitamin B-12…

  • Is required for the development and function of the central nervous system
  • Is necessary for the formation of red blood cells and DNA
  • Is involved in the breakdown of a protein called homocysteine, which is associated with an increased risk of heart disease and stroke
  • Helps maintain healthy nerve cells and is involved in the production of DNA and RNA
  • Works closely with vitamin B9 (folate or folic acid) to help make red blood cells and to help iron work better in the body
  • Aids in the production of S-adenosylmethionine (SAMe), a compound involved in immune function and mood

Vitamin B-12 deficiency is relatively common, and studies show that in the United States, approximately 6% of adults under 60 have a vitamin B12 deficiency, and close to 20% of those older than 60.

A deficiency or insufficiency of Vitamin B-12 can lead to many symptoms and even irreversible neurological issues if left untreated

Symptoms of B-12 deficiency

A deficiency of Vitamin B-12 has a number of potential symptoms, summarized here.

Fatigue and Weakness: One of the most significant symptoms of B-12 deficiency is fatigue and weakness. These symptoms develop because the body lacks sufficient red blood cells to carry oxygen throughout the body. Without enough oxygen, the muscles and brain become tired and weak.

Pale or Yellow Skin: A deficiency in B-12 can also affect the skin, causing it to become pale or yellowish. This symptom, known as jaundice, occurs when the body cannot remove bilirubin, a yellowish substance produced during the normal breakdown of red blood cells.

Numbness and Tingling: A lack of B-12 can affect the nervous system and cause numbness and tingling in the hands and feet. These symptoms happen due to nerve damage caused by the deficiency. In some severe cases, patients may experience difficulty walking or performing fine motor tasks.

Cognitive Impairment: B-12 has a critical role in maintaining healthy brain function. A deficiency in this vitamin can lead to cognitive impairment, including memory loss, difficulty concentrating, and mood changes. The symptoms can range from mild to severe and can often be mistaken for Alzheimer’s disease or other forms of dementia.

Mouth Ulcers/Sore Tongue: Another common symptom of B-12 deficiency is mouth ulcers and a sore, red tongue. These symptoms are due to a lack of red blood cells, which can cause the tissues in the mouth to be inflamed and more prone to injury.

Heart Palpitations: Vitamin B-12 is vital in maintaining a healthy heart. A deficiency in this nutrient can cause heart palpitations – an irregular heartbeat. This symptom is usually the result of anemia, which can be caused by a lack of B-12.

Other symptoms of vitamin B12 deficiency include:

  • Rapid breathing or shortness of breath
  • Headaches
  • Indigestion
  • Diarrhea
  • Loss of appetite
  • Problems with vision
  • Feeling weak or tired
  • Psychological problems, which can range from mild depression or anxiety to confusion and dementia

Diagnosing Vitamin B-12 deficiency

Blood tests are the most common way to diagnose a vitamin B-12 deficiency. The recommended lab testing for patients with suspected vitamin B12 deficiency includes a complete blood count and serum levels of vitamin B12.

  • Complete blood count (CBC): A CBC checks the levels of red and white blood cells in the body. This test can determine if an individual has anemia, a sign of a vitamin B-12 deficiency.
  • Serum B-12 test: This test measures the amount of B-12 in the blood. If the levels are low, it indicates a deficiency. A level of less than 150 pg per mL (111 pmol per L) is diagnostic for deficiency

Methylmalonic Acid (MMA) test: MMA is a substance produced in the body during the breakdown of certain amino acids. When there is a deficiency of vitamin B-12, MMA levels rise. Therefore, measuring the levels of MMA in the blood can help diagnose a vitamin B-12 deficiency, especially in an early, asymptomatic state.

Homocysteine test: The homocysteine test measures the levels of homocysteine in the blood. Homocysteine is an amino acid that is broken down by B-12 and folate. If the levels of homocysteine are high, it indicates a deficiency of these two vitamins.

Vitamin B-12, Hashimoto’s, and hypothyroidism

While up to 20% of adults have Vitamin B-12 deficiency, Hashimoto’s and hypothyroidism are risk factors for a deficiency in B-12. One study assessed the prevalence of vitamin B12 deficiency in patients with autoimmune Hashimoto’s disease. The study found that up to around half of all autoimmune thyroid patients had a vitamin B-12 deficiency!

Vitamin B-12 has anti-inflammatory properties and is crucial to the immune system’s function. Low levels of vitamin B-12 apparently exacerbate inflammation in the thyroid gland, worsening Hashimoto’s thyroiditis symptoms.

Another study published in Clinical Medicine Insights: Endocrinology and Diabetes found a high prevalence of B12 deficiency in hypothyroid patients, with approximately 40% being deficient. Low levels of vitamin B-12 impair the synthesis of thyroid hormone, leading to a worsening of hypothyroidism symptoms.

In another study, the incidence of a vitamin B12 deficiency was 27% in people with hypothyroidism, 17% in patients with subclinical hypothyroidism, and 18% in those with autoimmune thyroid disease.

A study released in 2023 looked at both vitamin D and B12 levels and their correlation with thyroid peroxidase antibodies (TPOAb) in patients with autoimmune hypothyroidism and found that higher levels of TPOAb are associated with low levels of both vitamins.

In a 2022 study on vitamin B12 deficiency in overt and subclinical hypothyroidism, researchers found that the rates of vitamin B12 deficiency are higher in patients with hypothyroidism compared to the general population.

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The Pernicious Anemia connection

Another condition that you should be aware of is pernicious anemia, an autoimmune condition commonly associated with Hashimoto’s thyroiditis and hypothyroidism. In pernicious anemia, the immune system attacks a protein called intrinsic factor, which is required for B12 absorption and results in low B12 levels.

One study found that 20% of Hashimoto’s disease patients have gastric autoimmunity, including pernicious anemia.

The symptoms of pernicious anemia can take years to surface, and early on, mild symptoms can be easily confused with the symptoms of Hashimoto’s thyroiditis or hypothyroidism. The common symptoms of pernicious anemia include:

  • Fatigue, lack of energy, or lightheadedness when standing up or with exertion
  • Pale skin
  • Diarrhea or constipation
  • Nausea, vomiting
  • Loss of appetite
  • Tingling feelings or pain
  • Trouble walking
  • Uncontrollable muscle movements
  • Confusion and memory loss
  • Headaches

To diagnose Pernicious Anemia, in addition to a CBC, serum folate, iron, and iron-binding capacity tests can help diagnose pernicious anemia or another type of anemia.

In addition, two antibody tests can help confirm a diagnosis of pernicious anemia. They include:

  • Antibodies to intrinsic factor: This test measures the presence of certain antibodies in the stomach and can help confirm the diagnosis of pernicious anemia.
  • Parietal cell antibodies: This is another classic test for pernicious anemia. About 90% of those with pernicious anemia will have parietal cell antibodies

If you have Hashimoto’s thyroiditis and are diagnosed with a Vitamin B-12 deficiency, it’s essential to discuss with your healthcare practitioner whether your deficiency may be caused by underlying autoimmune Pernicious Anemia.

Treating Vitamin B-12 deficiency

Generally, if you are deficient in B-12, you’ll need some form of supplementation: oral supplements (tablets or spray) or injections.

Intramuscular injection are a common way to treat B12 deficiencies. Typically, a patient with acute symptoms of Vitamin B-12 deficiency receives five to seven injections during the first week to restore the body’s reserves of this nutrient. Oral supplements, or periodic injections, may then be used to maintain adequate levels.

Interestingly, one study found that 58.3% of hypothyroid patients with B12 deficiency who received intramuscular vitamin B12 injections monthly noted an improvement in symptoms.

You can also make dietary changes to help reverse vitamin B12 deficiency:

  • Adjust your diet by eating more animal products like meat, seafood, dairy, and eggs, which can help boost your r vitamin B12 levels. You can also eat breads and plant-based milks fortified with Vitamin B12, making it easier for those who don’t consume animal products.
  • Avoid alcohol: Frequent alcohol consumption can damage your digestive system and make it difficult for your body to absorb vitamin B12 

MTHFR Mutation and Vitamin B-12

If you have MTHFR gene variations – and more than half the population does – it can impact your body’s ability to use vitamin B12. Here are some tips on how to take vitamin B12 if you have the MTHFR gene mutation:

  • Choose the right form of vitamin B12: Methylcobalamin is the active form of vitamin B12. Because MTHFR gene variations impair the body’s ability to convert B vitamins, methylated forms of B vitamins are considered the most bioavailable as they don’t need any conversion by the body
  • Consider high doses: you might need significant doses of methylcobalamin to treat a deficiency.
  • Check your homocysteine levels: If you have the MTHFR gene mutation, monitoring your homocysteine levels is essential. A good homocysteine reading should be between 7-8 µmol/L.

A note from Paloma

Low levels of vitamin B-12 can exacerbate the symptoms of hypothyroidism and Hashimoto’s thyroiditis. Therefore, it’s essential to maintain adequate levels of this vitamin through a balanced diet or supplements. If you’re experiencing symptoms of these thyroid disorders, it’s crucial to speak with your healthcare provider to determine the underlying cause and develop an effective treatment plan.

It’s important to note that early detection and treatment of Vitamin B-12 deficiency is vital because if left untreated, the deficiency can cause severe neurologic problems and blood diseases. The challenge is that the symptoms of vitamin B12 deficiency can overlap with the symptoms of hypothyroidism. The similarity of symptoms is why many experts recommend baseline vitamin B-12 testing when hypothyroidism is first diagnosed and periodically afterward.

Pernicious anemia can present very similarly to Hashimoto’s. So, if you have Hashimoto’s and are still struggling to get your symptoms under control, you should get checked for B12 deficiency and pernicious anemia.


Aon M, Taha S, Mahfouz K, Ibrahim MM, Aoun AH. Vitamin B12 (Cobalamin) Deficiency in Overt and Subclinical Primary Hypothyroidism. Clinical Medicine Insights: Endocrinology and Diabetes. 2022;15:117955142210866. doi:

Ness-Abramof R, Nabriski DA, Braverman LE, Shilo L, Weiss E, Reshef T, Shapiro MS, Shenkman L. Prevalence and evaluation of B12 deficiency in patients with autoimmune thyroid disease. Am J Med Sci. 2006 Sep;332(3):119-22. doi: 10.1097/00000441-200609000-00004. PMID: 16969140.

Chatterjee T, Gupta R, Choudhary S. A Study on Vitamin B12 Levels in Hypothyroid Patients Presenting to a Tertiary Care Teaching Hospital. J Assoc Physicians India. 2023 Jan;71(1):1. PMID: 37116022.

Aktaş HŞ. Vitamin B12 and Vitamin D Levels in Patients with Autoimmune Hypothyroidism and Their Correlation with Anti-Thyroid Peroxidase Antibodies. Med Princ Pract. 2020;29(4):364-370. doi: 10.1159/000505094. Epub 2019 Nov 29. PMID: 31779003; PMCID: PMC7445676.

Jabbar A, Yawar A, Waseem S, Islam N, Ul Haque N, Zuberi L, Khan A, Akhter J. Vitamin B12 deficiency common in primary hypothyroidism. J Pak Med Assoc. 2008 May;58(5):258-61. Erratum in: J Pak Med Assoc. 2009 Feb;59(2):126. Wasim, Sabeha [corrected to Waseem, Sabiha]. PMID: 18655403.

Wiebolt J, Achterbergh R, den Boer A, et al. Clustering of additional autoimmunity behaves differently in Hashimoto’s patients compared with Graves’ patients. European Journal of Endocrinology. 2011;164(5):789-794. doi:

Benites-Zapata VA, Ignacio-Cconchoy FL, Ulloque-Badaracco JR, Hernandez-Bustamante EA, Alarcón-Braga EA, Al-Kassab-Córdova A, Herrera-Añazco P. Vitamin B12 levels in thyroid disorders: A systematic review and meta-analysis. Front Endocrinol (Lausanne). 2023 Feb 22;14:1070592. doi: 10.3389/fendo.2023.1070592. PMID: 36909313; PMCID: PMC9994182.

Importance of vitamin B12 and MTHFR. MTHFR Gene Support. Published December 15, 2018. Accessed May 27, 2023.

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Mary Shomon

Patient Advocate

Mary Shomon is an internationally-recognized writer, award-winning patient advocate, health coach, and activist, and the New York Times bestselling author of 15 books on health and wellness, including the Thyroid Diet Revolution and Living Well With Hypothyroidism. On social media, Mary empowers and informs a community of more than a quarter million patients who have thyroid and hormonal health challenges.

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