Thiamine – Genetic Variations in Need for B1

Thiamine (thiamin), also known as 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 and needed in the production of A/TP, 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]

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

Thiamine transporter gene:

An SLC35F3 (thiamin transporter) variant is linked to hypertension. There have been other studies showing that thiamine supplementation reduces blood pressure in some, possibly due to the increase in pyruvic and lactic acid found in thiamine deficiency.[ref] [ref]

• rs17514104 (not in 23andme) –  A is minor allele.  Those homozygous for the minor allele (A/A), had a significant reduction in blood thiamine content and higher blood pressure. [ref]

SLC19A2 is the gene that codes for the Thiamine transporter 1. Mutations in this gene can cause thiamine-responsive megaloblastic anemia.

• rs28937595 – A/A is considered pathogenic for thiamin-responsive megaloblastic anemia.[ref]
• rs121908540 – T/T is considered pathogenic for thiamin-responsive megaloblastic anemia. (23andMe v5 only)

Rare Genetic Disorders:

Thiamine is also involved in 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 these disorders and thiamine some more.

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]

More to read:

This post is just scratching the surface of all the ways that thiamine is used in the body.

• Thiamin (Oregon State University)
• Vitamin B1 (Thiamine)

Thiamine Supplements:

If you don’t eat a lot of foods that contain thiamine, there are thiamine supplements available.  Most good B-complexes, such as Jarrow B-Right, include thiamine.  There are also individual supplements, such as Seeking Health Thiamine.  If you don’t want the extra excipients in the capsules, PureBulk also sells thiamine powder.