Thiamine and Thyroid Fatigue

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Thiamine, a very important vitamin, plays an essential role in our body, including the health of our thyroid.

Could thiamine deficiency possibly be the reason for troubling fatigue that patients with thyroid issues often struggle with?

What do you need to know about thiamine?

Thiamine, also known as thiamin and Vitamin B1, is one of the essential eight B vitamins. It is a water-soluble vitamin, like other types of Vitamin Bs. This very important vitamin is included in maintaining many body functions. One of those body functions is converting carbohydrates, that we intake from food and drinks, into energy that our body can use.[i]

Other responsibilities of his reference to the proper digestion of protein and fats, which revolves around the proper release of hydrochloric acid in the stomach, as well as being included in muscle contractions and the conduction of nerve signals, among other body functions. The recommended daily intake of Vitamin B1 is 1.1 mg for women and 1.2 mg for men over the age of 18. However, these numbers change depending on different factors such as age, general health status, etc. For example, for pregnant and breastfeeding women, the recommended daily intake is around 1.4 mg.

The symptoms of thiamine deficiency

Our bodies are unable to produce thiamine. This means that we need to be careful and make sure that we satisfy our daily need for Vitamin B1 through the food that we are eating. And although thiamine deficiency is not common in the developed countries, it is still possible that it will happen. Thiamine deficiency, as the term suggests, is a condition in which the body lacks the required daily amounts of Vitamin B1.

There are also various factors that increase the risk of thiamine deficiency. These would include struggling with any of the following health issues:

  • Cancer;
  • Diabetes;
  • Morning sickness during early pregnancy;
  • Alcohol abuse, etc.

Factors such as having bariatric surgery and being of old age also increase the risk of thiamine deficiency. Many people often do not realize that they are struggling with a thiamine deficiency because its symptoms are often overlooked. The list of symptoms includes:

  • Loss of appetite;
  • Fatigue;
  • Irritability;
  • Muscle weakness;
  • Nausea and vomiting;
  • Blurry vision;
  • Delirium;
  • Shortness of breath;
  • Changes in heart rate, etc.

Luckily, in most cases, thiamine deficiency is effectively prevented and treated by simply adding more of the thiamine-rich foods in the daily diet. If the individual is worried that he/she fails to introduce enough thiamine through food, thiamine supplementation is also available to use.

You can use a special Vitamin B1 supplement or take a supplement that offers all of the eight essential Vitamin Bs instead. Do talk to your doctor about the best supplement in terms of your unique condition.

Three ways in which thiamine deficiency is causing poor thyroid health

Apart from the general symptoms that we mentioned earlier, caused by thiamine deficiency, other negative effects are expected to happen as well. Some of these effects refer to the function of a very important gland in our body – the thyroid gland. In the following, we will discuss three ways in which a known thiamine deficiency is causing poor thyroid health.

Thiamine deficiency increases the risk of estrogen dominance

Estrogen is a very important hormone. However, even good things can do harm when they are not maintained within the normal levels in the body. And so, when there is estrogen dominance occurring in the body, there is a high risk of hypothyroidism, or underactive thyroid, from happening.[ii]

One of the many functions of thiamine in the body is to make sure that the extra estrogen that is being produced is properly detoxified. Therefore, Thiamine is directly maintaining the normal estrogen levels. Without adequate thiamine, the liver is unable to inactivate and detoxify estrogen, and so, its levels begin to rise. Having too much estrogen in the body reflects poorly on the function of the thyroid gland, suppressing it and its metabolism, thus the symptoms of hypothyroidism begin to occur.

Thiamine deficiency increases the risk of diabetes

Similar to estrogen dominancy, hypothyroidism and high blood sugar levels also go hand-in-hand together. Hypothyroidism is often accompanied by insulin resistance, and with that, an increased risk of diabetes. When the body is unable to metabolize carbohydrates, which we mentioned happens with the help of thiamine, it is unable to use the triiodothyronine – T3 hormone.

That made researchers wonder if thiamine supplementation would help the case and improve the state of the thyroid gland and the symptoms of hypothyroidism. And as the results showed, in a study, it did – the blood sugar levels were reduced to normal, the insulin resistance was improved, and the ability to metabolize carbohydrates was improved as well. In addition, the condition of the thyroid gland improved as well.[iii]

Thiamine deficiency increases the levels of ammonia

In the process of muscle protein-breakdown, as an energy fuel, a compound called ammonia is being released. High ammonia levels in the body are associated with psychological problems such as brain fog, tiredness, confusion, and possibly death, among other health issues. For a patient with hypothyroidism, who is already struggling with many of these symptoms, his/her condition can worsen due to the fact that these symptoms are accelerated due to the high ammonia levels in the body.

It is no unusual for hypothyroidism patients to struggle with high ammonia levels since they are experiencing high protein breakdown. In fact, this is one of the main causes of the common brain fog that these patients are often experiencing. Struggling with a thiamine deficiency at the same time can worsen the present symptoms even further. On the other hand, supplementing with a thiamine supplement can help prevent the protein breakdown, thus limiting the levels of ammonia which is being released in the body.

Can thiamine deficiency be the cause of thyroid fatigue?

If you go back, you will see fatigue as one of the common signs and symptoms of thiamine deficiency. Fatigue is also a common symptom of hypothyroidism and Hashimoto’s thyroiditis, as two of the most common thyroid issues known to man. Struggling with a thiamine deficiency while also struggling with a thyroid issue such as hypothyroidism can worsen the present symptoms and even make them unbearable.

On the other hand, hypothyroidism patients are often deficient in thiamine as well. In addition, those with autoimmune diseases may also have an imbalance in certain enzymes with reduces the body’s ability to process thiamine at a cellular level, as researchers suggest.

After multiple studies showed that thiamine supplementation efficiently helped reduce the present fatigue in patients struggling with inflammatory bowel disease (IBD)[iv], researchers started thinking about using thiamine supplementation to treat the present fatigue in hypothyroidism patients as well.

In 2014, researchers gave thiamine supplements to three patients diagnosed with Hashimoto’s thyroiditis, who also struggled with fatigue as well. As a part of the research, the participants’ thiamine levels were measured before and after the given thiamine supplementation. While one patient was given an injection of 100 mg thiamine every four days, the two other patients were given an oral dose of 600 mg thiamine every day.

What the results showed was that with the help of the proper thiamine supplementation, they all experienced either partial or complete regression of their fatigue. Their fatigue was gone within hours or days after they received the thiamine supplementation. This made researchers believe that the fatigue within the hypothyroidism patients could be the result of an unknown thiamine deficiency.[v] Luckily for these patients, a simple thiamine supplementation was the answer to their fatigue problems. Note that this is only one study that has looked into the use of thiamine supplementation in the treatment for fatigue within hypothyroidism patients. More research needs to be done, although what we do know so far is quite promising.

The cause for thiamine deficiency, and with that fatigue, within hypothyroidism patients may be hiding within their low stomach acid levels as well. With low stomach acid levels, these patients are facing the inability to properly absorb enough thiamine from their diet, thus contributing to the occurrence of thiamine deficiency. But even if this is the cause for fatigue, thiamine supplementation should help the cause and help reduce the present fatigue, as well as any other symptoms caused by thiamine deficiency.

How to include more thiamine in your daily diet

As we mentioned earlier, since our body is unable to produce this vital vitamin on its own, it is up to us to satisfy the daily recommended needs for thiamine through our diet. Luckily for us, there are so many ways in which you can add more thiamine to your daily diet.

There is plenty to choose from – from plant-based to animal-based choices. This is very important since vegans and vegetarians are often exposed to the risk of struggling with a thiamine deficiency since the biggest thiamine sources are animal-based ones.

The list of thiamine-rich foods includes:

  • Black beans, cooked;
  • Lentils, cooked;
  • Beef liver;
  • Edamame, cooked;
  • Asparagus;
  • Pork loin, cooked;
  • Macadamia nuts, raw;
  • Eggs;
  • Nuts;
  • Seeds;
  • Fortified breakfast cereals, pasta, bread, rice, and flour, etc.[vi]

The biggest thiamine source of all this is the macadamia nuts, with 100 grams of macadamia nuts containing around 80% of the recommended daily intake of thiamine. There are other sources that you can explore as well, and as always, you can use a thiamine supplement or a Vitamin B complex supplement to add more of these important vitamins to your daily diet.

If you struggle with hypothyroidism or any other thyroid issue, make sure to introduce more of these animal-based and plant-based thiamine sources as a part of your diet. In addition, consult your doctor about using proper thiamine supplementation. Naturally, you will be expected to introduce more thiamine than a healthy individual.


With so many tasty sources of thiamine, it seems impossible to feel the negative effects of a thiamine deficiency. And yet, there are many people every day that struggle with it.

Although it is worth mentioning that most of those people are struggling with accompanying health issues as well – due to medical conditions such as hypothyroidism. Introducing foods rich in Vitamin B complexes or taking additional supplements may help in increasing Thiamine levels and reducing Thiamine induced fatigue.


[i] Lonsdale, D. (2006). A Review of the Biochemistry, Metabolism, and Clinical Benefits of Thiamin(e) and Its Derivatives. Evidence-Based Complementary and Alternative Medicine3(1), 49–59. doi: 10.1093/ecam/nek009
Retrieved from

[ii] Santin, A. P., & Furlanetto, T. W. (2011). Role of Estrogen in Thyroid Function and Growth Regulation. Journal of Thyroid Research2011, 1–7. doi: 10.4061/2011/875125
Retrieved from

[iii] Shahmiri, F. A., Soares, M. J., Zhao, Y., & Sherriff, J. (2013). High-dose thiamine supplementation improves glucose tolerance in hyperglycemic individuals: a randomized, double-blind cross-over trial. European Journal of Nutrition52(7), 1821–1824. doi: 10.1007/s00394-013-0534-6
Retrieved from

[iv] Costantini, A., & Pala, M. I. (2013). Thiamine and Fatigue in Inflammatory Bowel Diseases: An Open-label Pilot Study. The Journal of Alternative and Complementary Medicine19(8), 704–708. doi: 10.1089/acm.2011.0840
Retrieved from

[v] Costantini, A., & Pala, M. I. (2014). Thiamine and Hashimotos Thyroiditis: A Report of Three Cases. The Journal of Alternative and Complementary Medicine20(3), 208–211. doi: 10.1089/acm.2012.0612
Retrieved from

[vi] Office of Dietary Supplements – Thiamin. (n.d.).
Retrieved from

1 Comment
  1. Reply
    S B Lewis October 2, 2020 at 12:45 pm

    vaccines can cause trouble with the thyroid…

    Leave a reply