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The Role of Vitamin B12 in Thyroid Health

Written by Dr. Group, DC Founder
People are running on the beach. Vitamin B12 is one of the several nutrients that support thyroid health.

Your personal wellness and the efficiency at which your body operates is a direct result of the quality and completeness of the nutrients you consume. Complete nutrition promotes complete wellness, while nutritional deficiencies result in wellness deficiencies. Energy levels and metabolism are some of the most noticeable status indicators of wellness.

To encourage both to be at their best, pay special attention to thyroid gland health and vitamin B12 intake. A sluggish thyroid, or hypothyroidism, may cause you to be deficient in vitamin B12, and the resulting vitamin B12 deficiency can further exacerbate the slow thyroid or negatively affect energy.[1]

The Thyroid Gland and Its Function

The thyroid gland is a small, butterfly-shaped gland in the front of your neck. It’s responsible for synthesizing thyroid hormones T3 and T4 which control your metabolism and even your heartbeat.[2]

The gland secretes more thyroid hormones when you want a boost in energy, such as when you’re cold. The hormone boost cues your body to speed up your metabolism, or the rate at which chemical reactions occur, and this generates more heat and raises your body’s temperature. Consequently, thyroid hormones affect your basal metabolic rate (BMR) and that determines how many calories you burn while you’re at rest.[3]

Functions of Vitamin B12

Although daily B12 requirements are fairly low (just 2.4 micrograms for teenagers and adults[4]), it plays a crucial role in metabolic and cellular processes. B12 is the catalyst for red blood cell production, DNA synthesis, protein conversion, neurological function,[5] fatty acid synthesis,[6] and nerve health.[4]

Symptoms and Effects of B12 Deficiency

The process of metabolizing vitamin B12 is a complicated one, and there are several ways to develop a deficiency. Vitamin B12 found naturally in food is bound to proteins. Once consumed and in the stomach, it separates from these proteins through the action of pepsin and gastric acid. From here, it immediately binds to R protein from saliva which protects it from damage in the acidic environment. In the duodenum, the first section of the small intestine, the B12-R protein complex splits apart.

Intrinsic factor (IF), a protein secreted in the stomach, joins B12 and safely transports it past the protein-digesting enzymes that would otherwise destroy the vitamin. Once it reaches the last part of the small intestine, the ileum, it’s absorbed from the GI tract where B12 detaches from IF and joins transcobalamin to become B12 — TC-II. This last complex is taken up by the bone marrow, liver, and other cells. The liver stores 90 percent of a person's B12.[1]

A B12 deficiency may result when you either don’t consume enough B12 or your body doesn’t absorb enough B12. Absorption issues can result from inadequate intrinsic factor, digestive enzyme issues, or organ damage. Symptoms of deficiency vary depending on severity. The most common include fatigue, constipation, decreased appetite, tingling in the hands and feet, impaired memory, depression, and soreness of the tongue.[4]

Some people have a higher risk of B12 deficiency:
  • Older adults, due to decreased hydrochloric acid in the stomach.[4]
  • People whose bodies don’t produce enough intrinsic factor.[4]
  • Vegetarians and vegans who don’t get B12 from food.[4]
  • People with conditions that irritate mucosal lining in the stomach and intestines, such as Crohn’s or celiac disease,[7] chronic alcoholism, or inflammatory bowel disease.[8]

Effect of Hypothyroidism on B12 Absorption

Hypothyroidism can compromise your ability to absorb vitamin B12. An infection of Helicobacter pylori bacteria may also interfere with gastric secretions and hinder B12 absorption.[9]

Experts believe that 4.6 percent of the U.S. population age 12 and up suffers from hypothyroidism.[6] One study found that approximately 40 percent of hyperthyroid patients also suffer from a B12 deficiency. Adding supplementary B12 to these patients’ routines improved weakness, memory, mood, and other symptoms.[10] The USDA recommends B12 supplementation for people at risk of deficiency because it's more easily absorbed than B12 from food sources.[11]

Dietary Sources of Vitamin B12

The most common sources of B12 are meat, seafood,[12] eggs, and dairy.[13] Since vitamin B12 is produced by a soil-based bacteria,[14] animals pick it up while foraging for food. Some vegetarian sources such as fortified cereals and nutritional yeast do exist if you're trying to avoid animal products. A B12 supplement is a great way to fill the gaps in your nutritional intake.

The Benefits of B12 Supplementation

A B12 supplement is invaluable, especially for older adults. The right B12 supplement is easily absorbed and provides the B12 the human body requires. All people at risk of B12 deficiency should consider a B12 supplement.[4] Our Vitamin B12 supplement offers the most bioactive forms of B12 — methylcobalamin, adenosylcobalamin, and hydroxocobalamin.

While B12 is an essential vitamin for supporting thyroid health, the importance of iodine and selenium cannot be overlooked. That’s why we created the Thyroid Health Kit™; it contains all of our best thyroid support supplements — vitamin B12, selenium, and iodine.

References (14)
  1. Kibirige, Davis, and Raymond Mwebaze. “Vitamin B-12 Deficiency Among Patients with Diabetes Mellitus: Is Routine Screening and Supplementation Justified?” 12. (2013): n.pag. Web. 23 Aug. 2016.
  2. “Thyroid diseases.” NIH. U.S. National Library of Medicine, 18 Aug. 2016. Web. 23 Aug. 2016.
  3. “How does the thyroid work? - PubMed health - national library of medicine - PubMed health.” (2015): n.pag. Web. 23 Aug. 2016.
  4. “Office of dietary supplements - vitamin B-12.” 24 June 2011. Web. 23 Aug. 2016.
  5. “Office of dietary supplements - dietary supplement fact sheet: Vitamin B-12.” NIH. 11 Feb. 2016. Web. 23 Aug. 2016.
  6. "Hypothyroidism (Underactive Thyroid) What is hypothyroidism?" Australian Government National Health and Medical Research Council. 1 Jan. 2005. Web. 23 Aug. 2016.
  7. “Hypothyroidism (Underactive Thyroid).” National Institute of Diabetes, Digestive and Kidney Disorders. 18 Aug. 2016. Web. 23 Aug. 2016.
  8. America, Colitis Foundation of. “CCFA: Nutrition and IBD.” Crohn’s & Colitis Foundation of America. 2016. Web. 23 Aug. 2016.
  9. Lahner, Edith, and Bruno Annibale. “Pernicious Anemia: New Insights from a Gastroenterological Point of View.” 15.41 (2009): n.pag. Web. 23 Aug. 2016.
  10. Jabbar, A, et al. “Vitamin B-12 Deficiency Common in Primary Hypothyroidism.” JPMA. The Journal of the Pakistan Medical Association. 58.5 (2008): 258–61. Web. 23 Aug. 2016.
  11. “Questions to ask before taking vitamin and mineral supplements.” 22 Aug. 2016. Web. 23 Aug. 2016.
  12. “Foods highest in vitamin B-12.” SELF Nutrition Data. 2014. Web. 23 Aug. 2016.
  13. Wax, Emily, et al. “Vegetarian diet: MedlinePlus medical encyclopedia.” MedlinePlus. 12 Jan. 2014. Web. 23 Aug. 2016.
  14. "MIT biologists solve vitamin puzzle." Web. 21 Mar. 2007.

†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.


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