Thiamine – Genetic Variations in Need for 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. Thiamine is needed in the production of ATP, which is used in every cell for energy.
Severe deficiency of thiamin leads to beriberi, and less severe deficiency can cause fatigue, gut issues, headaches, and irritability.[ref][ref]
Symptoms of beriberi include emotional problems, weakness, pain, irregular heartbeat, and edema. Dry beriberi symptoms include peripheral neuropathy like symptoms; wet beriberi symptom include edema, cardiomyopathy, and lactic acidosis.[ref]
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 symptom. Having a low intake of thiamine is linked to an increased risk of cataracts.
Thiamine deficiency in the elderly can also lead to misdiagnoses for dementia-related illnesses or increase the risk of these disease.[ref][ref] In animal studies, supplementing with thiamine “rescued cognitive deficits and reduced Aβ burden in amyloid precursor protein”. [ref]
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 an excellent and free way 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:
SLC19A2 is the gene that codes for the Thiamine transporter 1, which is a protein needed for thiamine uptake in the intestines. Mutations in this gene can cause thiamine-responsive megaloblastic anemia. Without this thiamine transporter, the absorption of thiamine in the intestines is severely limited.
Check your genetic data for rs28937595 (23andMe v4; AncestryDNA)
- T/T: pathogenic for thiamin-responsive megaloblastic anemia.[ref]
- C/T: carrier for thiamine-responsive megaloblastic anemia
- C/C: typical
Check your genetic data for rs121908540 (23andMe v5; AncestryDNA):
- A/A: pathogenic for thiamin-responsive megaloblastic anemia. [ref]
- A/G carrier for thiamin-responsive megaloblastic anemia.
- G/G: typical
Check your genetic data for rs74315373 (AncestryDNA only):
- A/A: pathogenic for thiamin-responsive megaloblastic anemia. [ref]
- A/G carrier for thiamin-responsive megaloblastic anemia.
- G/G: typical
Check your genetic data for rs74315374 (AncestryDNA)
- T/T: pathogenic for thiamin-responsive megaloblastic anemia.[ref]
- C/T: carrier for thiamine-responsive megaloblastic anemia
- C/C: typical
Check your genetic data for rs74315375 (AncestryDNA)
- T/T: pathogenic for thiamin-responsive megaloblastic anemia.[ref]
- C/T: carrier for thiamine-responsive megaloblastic anemia
- C/C: typical
Other Rare Genetic Disorders:
Thiamine is also involved in the treatment 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 BCA/A 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 an easy to overlook 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.
Some foods contain anti-thiamine factors. Tea and coffee both decrease thiamin absorption, and certain mycotoxins (mold toxin) can act as anti-thiamine factors.
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