Hashimoto's Disease-Related Fatigue and Thiamine Levels

Hypothyroidism can interfere with absorption of this important nutrient

Thiamine (or vitamin B1) is one of many B-complex vitamins. It is required for proper metabolism and is necessary for the production of adenosine triphosphate (ATP), which provides energy used by every cell in the body. If you have Hashimoto's thyroiditis, you may not absorb thiamine properly, leading to a deficiency that can exacerbate fatigue, a common symptom of Hashimoto's disease.

Thiamine is not stored in the body, so it is necessary to get a consistent supply of it from food and, in some cases, supplements.

What Is Hashimoto’s Disease?

Verywell / Emily Roberts

Thiamine Deficiency and the Thyroid

Among thiamine's many benefits are metabolic regulation, stomach acid release, and improved fat and protein digestion. The brain and nervous system, especially, rely heavily on the energy stimulated by thiamine.

One reason Hashimoto’s patients may be deficient in this important vitamin is that they often have low stomach acid or difficulty releasing enough of it to effectively absorb nutrients from food, including thiamine. Researchers also suspect that those with autoimmune diseases may have an imbalance in certain enzymes, reducing the body's ability to process thiamine at the cellular level.

Based on a 2013 study that found that thiamine improved fatigue in inflammatory bowel disease (IBD) patients, researchers decided to evaluate whether the chronic fatigue seen in inflammatory and autoimmune diseases might be evidence of a thiamine deficiency.

Their 2014 study included three patients who were on thyroid hormone replacement treatment for Hashimoto's thyroiditis and who also suffered from fatigue. The patients all had free thiamine blood tests measured before and after receiving high doses of thiamine—either 600 mg/day of thiamine orally or 100 mg/ml intravenously every four days.

All of the patients experienced partial or complete regression of fatigue within a few hours or days of the start of the treatment. This led the researchers to conclude that giving large quantities of thiamine restores thiamine-dependent processes and relieves fatigue.

Bear in mind that this was a very small study and more research on the relationship between thyroid function and thiamine needs to be done to support these findings.

Other factors that can contribute to thiamine deficiency include:

  • Poor dietary intake
  • Diabetes
  • Anorexia and other eating disorders
  • Weight loss surgery
  • Excessive alcohol consumption
  • Digestive absorption problems
  • Metabolic imbalances

In addition to fatigue, thiamine deficiency can cause:

  • Nausea
  • Headache
  • Irritability
  • Depression
  • Abdominal discomfort
  • Beriberi (a rare disease caused by severe thiamine deficiency)

Sources of Thiamine

We depend on our daily diet for thiamine, and since the vitamin is not stored in the body, a consistent dietary intake is necessary to maintain sufficient levels.

The recommended daily intake (RDI) is 1.2 mg for men and 1.1 mg for women. Experts feel that the majority of Americans do get sufficient thiamine from their food intake.

Good sources of thiamine include:

  • Beef liver
  • Black beans, cooked
  • Lentils, cooked
  • Macadamia nuts, raw
  • Edamame, cooked
  • Pork loin, cooked
  • Asparagus
  • Fortified breakfast cereal
  • Enriched, fortified, and whole grain products such as bread, cereals, rice, pasta, and flour
  • Eggs
  • Nuts and seeds

If you're experiencing fatigue despite being treated for hypothyroidism, talk to your healthcare provider about your thiamine levels. A blood test known as an erythrocyte transketolase test can diagnose a deficiency.

A Word From Verywell

If your healthcare provider diagnoses you with thiamine deficiency, increasing your thiamine intake through strategic food choices or supplementation should help you feel less fatigued.

Excess thiamine is excreted in the urine, so even at higher doses, the vitamin is considered safe. There are no reports of toxicity of dietary thiamine or thiamine supplementation.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Costantini A, Pala MI. Thiamine and Hashimoto's thyroiditis: a report of three cases. J Altern Complement Med. 2014;20(3):208-11. doi:10.1089/acm.2012.0612

  2. Costantini A1, Pala MI. Thiamine and fatigue in inflammatory bowel diseases: an open-label pilot studyJ Altern Complement Med. Aug 2013;19(8):704-8. doi:10.1089/acm.2011.0840

  3. Pácal L, Kuricová K, Kaňková K. Evidence for altered thiamine metabolism in diabetes: Is there a potential to oppose gluco- and lipotoxicity by rational supplementation? World J Diabetes. 2014;5(3):288‐295. doi:10.4239/wjd.v5.i3.288

  4. PennState Hershey Milton S. Hershey Medical Center. Vitamin B1 (thiamine).

  5. NIH MedlinePlus. Beriberi.

Additional Reading
  • National Academy of Hypothyroidism. Thyroid and thiamine.

  • Oregon State University Linus Pauling Institute. Micronutrient Information Center: Thiamin.

By Mary Shomon
Mary Shomon is a writer and hormonal health and thyroid advocate. She is the author of "The Thyroid Diet Revolution."