Thiamine: Genetics and the need for vitamin B1

Thiamine (vitamin B1) is a water-soluble vitamin that serves as a cofactor in the metabolism of carbohydrates, branch chain amino acids, and fatty acids. It is essential, meaning you have to get it from food. Not to mention, ATP production, used in every cell for energy, requires thiamine.

The importance of thiamine:

Severe deficiency of thiamine leads to a disease called beriberi. Less severe deficiency can cause fatigue, gut issues, headaches, and irritability.[ref]

Symptoms of beriberi include:[ref]

• emotional problems
• weakness
• muscle pain
• irregular heartbeat
• edema
• peripheral neuropathy
• cardiomyopathy
• lactic acidosis

Thiamine, in various forms, is an essential cofactor in the mitochondria in the production of energy. Thus a deficiency in this vitamin can cause a variety of different symptoms. In addition, a link between having a low intake of thiamine and an increased risk of cataracts exists.

Thiamine deficiency in the elderly can also lead to misdiagnoses for dementia-related illnesses or increase the risk of these diseases.[ref][ref] In animal studies, supplementing with thiamine “rescued cognitive deficits and reduced Aβ burden in amyloid precursor protein”.[ref]

Thiamine and Your Diet:

Food sources of thiamine include pork, enriched rice, and wheat products, wheat germ, legumes, and sunflower seeds. The daily recommended intake for thiamine is around 1.2 – 2 mg per day.

How do you know if you are getting enough thiamine in your diet?
For someone on a  grain-free diet who doesn’t eat a lot of pork, it may be worth tracking your intake for a week or so to make sure that you are getting enough thiamine.  Cronometer.com is a free online app to keep track of your nutrient intake.

While full-blown beriberi is rare in the modern world due to thiamine-fortified foods, symptoms from thiamine insufficiency are possible due to restrictive diet fads, anorexia, or bariatric surgery.

People who drink a lot of alcohol can end up with a form of thiamine deficiency, known as Wernicke’s encephalopathy, due to liver problems and reduced uptake of thiamine in the intestines.

Genetic variants:

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The SLC19A2 gene codes for the Thiamine transporter 1, a protein that is needed for thiamine uptake in the intestines. Mutations in this gene have shown to cause thiamine-responsive megaloblastic anemia. Without this thiamine transporter, the absorption of thiamine is severely limited in the intestines.

Other Rare Genetic Disorders:

Thiamine is also involved in the treatment of several rare genetic disorders.  These are usually diagnosed in infants, but those who are heterozygous for the mutations listed below may want to look into the link to thiamine.

Pyruvate dehydrogenase complex deficiency (PHDC) is sometimes responsive to thiamine.

• rs28933391 – A/A is considered pathogenic for Pyruvate dehydrogenase deficiency.
• rs28935769 – C/C is considered pathogenic for pyruvate dehydrogenase deficiency.

An inborn error of branch chain amino acid metabolism, Maple syrup urine disease,  can be responsive to thiamine.  Mutations in the BCKDHB gene cause this error in BCAA metabolism.

• i3002808–  C/C is considered pathogenic for Maple Syrup Urine Disease[ref]
• i4000422– A/A is considered pathogenic for Maple Syrup Urine Disease [ref]
• rs74103423– A/A is considered pathogenic for Maple Syrup Urine Disease[ref]

Lifehacks:

Thiamine insufficiency is easy to overlook as a cause of a lot of symptoms that mimic other conditions. If you suspect that you aren’t getting enough thiamine in your diet, supplements are readily available.

Foods that are high in thiamine include:

• liver
• black beans, legumes
• macadamia nuts
• pork

Some foods contain anti-thiamine factors.  For example, tea and coffee both decrease thiamin absorption, and certain mycotoxins (mold toxin) can act as anti-thiamine factors. If you are taking supplemental thiamine, you may want to avoid taking it with tea or coffee.

Blood tests for thiamine levels are readily available. Talk with your doctor or order it on your own through a place like Ulta Lab Tests.  (Shop around if you’re ordering it on your own – prices vary quite a bit on online lab test websites)

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