What does vitamin B1 do?

 

The B vitamins are usually referred to as a whole, but each vitamin within the complex plays a unique role in health. Among them, vitamin B1, or thiamin, is most crucial to energy metabolism and nervous system function. Without adequate amounts of it, functions in the body may not operate as smoothly as they otherwise would.

Below, we examine more intently what vitamin B1 is, how the body utilises it and why sufficient quantities of it are necessary.

What is vitamin B1?

Vitamin B1, or thiamin, is a water-soluble vitamin that belongs to the B-complex family.¹ Being water-soluble means that the body does not store large amounts of it, and any excess is usually excreted through urine. This is why it’s important to get a regular intake through food sources or supplements.

Thiamin was the first B vitamin to be discovered, which is why it carries the name B1. It plays a central role in energy metabolism and is vital for cells to convert carbohydrates into usable energy.² Natural sources of thiamin include whole grains, legumes, nuts, seeds, pork and fortified cereals.³

Because the body cannot produce thiamin itself, maintaining a balanced diet rich in these foods is important. In some cases, supplementation may be beneficial, particularly if dietary intake is inadequate or if you have a health condition that increases the risk of deficiency. 

What does vitamin B1 do for the body?

It might not be one of the best known vitamins, but thiamin is vital for several functions within the body, including supporting the metabolism, the nervous system, the mind and the heart.⁴

The metabolism

One of the most important roles of vitamin B1 is its contribution to a normal energy-yielding metabolism. This means that thiamin helps the body to break down and convert the carbohydrates in our diet into glucose, which is then used as a primary energy source by cells.⁵

Without enough thiamin, it can become harder for the body to convert food into energy, leading to fatigue, muscle weakness or difficulty concentrating.⁶ People with higher energy demands, such as athletes, may have a greater need to ensure their diet provides enough vitamin B1 to keep up with their body’s requirements.

The nervous system

Thiamin also contributes to the normal functioning of the nervous system.⁴ The nervous system is responsible for transmitting messages between the brain, spinal cord and the rest of the body.

By helping nerve cells generate energy, thiamin supports the proper functioning of these communication pathways. A deficiency in vitamin B1 can result in neurological symptoms such as tingling sensations, numbness or, in severe cases, more serious conditions like peripheral neuropathy.⁷

The mind

In addition to supporting physical processes, thiamin contributes to normal psychological function.⁴ This means it plays a role in mental wellbeing, cognitive function and mood regulation.

Some research suggests that low levels of thiamin may be linked to irritability, memory issues or reduced concentration.⁸ While more studies are needed to fully understand the relationship between thiamin and mental health, ensuring adequate intake may help support clarity of thought and overall wellbeing.

The heart

Finally, thiamin contributes to the normal function of the heart.⁴ The heart, like all muscles, relies heavily on a steady supply of energy to function properly. Since vitamin B1 is essential for energy metabolism, it indirectly supports cardiovascular health by ensuring that heart muscle cells can generate the energy they need.

Thiamin deficiency has been associated with cardiovascular problems in the past, particularly in populations where diets were low in whole grains and heavily reliant on processed foods.⁹ Ensuring a regular intake of vitamin B1 through diet or supplements may therefore contribute to maintaining a healthy heart.

 

For those who may struggle to get enough thiamin through food alone, supplementation with a B-complex product can be a practical option, as this provides thiamin alongside other essential B vitamins that work together to support health.

Vitamin B1, or thiamin, may not always get as much attention as other nutrients, but it plays a crucial role in keeping the body’s energy systems running smoothly, supporting the nervous system, promoting psychological function and contributing to heart health.

References

1. National Institutes of Health. (2021). Thiamin fact sheet for health professionals. Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/ 
2. NHS. (2023). Vitamins and minerals – Thiamin (vitamin B1). National Health Service. https://www.nhs.uk/conditions/vitamins-and-minerals/thiamin/
   
3. Harvard T.H. Chan School of Public Health. (2023). Vitamin B1 (Thiamin). https://www.hsph.harvard.edu/nutritionsource/vitamin-b1/
   
4. Great Britain Nutrition and Health Claims Register. (2024). Authorised nutrition and health claims. UK Government. https://www.gov.uk/government/publications/nutrition-and-health-claims-great-britain-register
   
5. Combs, G. F., & McClung, J. P. (2017). The vitamins: Fundamental aspects in nutrition and health (5th ed.). Academic Press.
   
6. MedlinePlus. (2023). Thiamin. U.S. National Library of Medicine. https://medlineplus.gov/thiamin.html
   
7. Singleton, C. K., & Martin, P. R. (2001). Molecular mechanisms of thiamin utilisation. Current Molecular Medicine, 1(2), 197–207. https://doi.org/10.2174/1566524013363470
8. Smith, A. D., & Refsum, H. (2016). B vitamins and mental health. Nutrition Reviews, 74(5), 335–345. https://doi.org/10.1093/nutrit/nuw002
9. Whitfield, K. C., Bourassa, M. W., Adamolekun, B., Bergeron, G., Bettendorff, L., Brown, K. H., Cox, L., Fattal-Valevski, A., Fischer, P. R., Guo, X., Hiffler, L., Hlaing, L. M., Jameson, J. L., Khounsy, S., Kounnavong, S., et al. (2018). Thiamine deficiency disorders: Diagnosis, prevalence, and a roadmap for global control programs. Annals of the New York Academy of Sciences, 1430(1), 3–43. https://doi.org/10.1111/nyas.13919