Does B1 deficiency cause anemia?

November 22, 2025 •

4 min read

In a 2023 study of hospitalized patients, researchers found a significant association between anemia and vitamin B1 deficiency, prompting the medical community to consider this link. But does B1 deficiency cause anemia directly, and how common is it? The connection is complex, often tied to a rare genetic disorder or issues with malabsorption.

Quick Summary

While not a common cause, vitamin B1 deficiency can lead to a rare, genetic form of megaloblastic anemia called TRMA. General deficiency may also be associated with anemia in some vulnerable populations, particularly those with malabsorption issues.

Key Points

TRMA is the Primary Link: The clearest and most direct connection between B1 deficiency and anemia is the rare genetic disorder Thiamine-Responsive Megaloblastic Anemia (TRMA), which causes megaloblastic anemia.
Gene Mutation is the Cause: TRMA is an autosomal recessive condition resulting from a mutation in the SLC19A2 gene, which impairs the transport of thiamine into cells.
Thiamine Affects Hematopoiesis: Vitamin B1 is a coenzyme essential for the pentose phosphate pathway, which provides precursors for nucleic acid synthesis required for red blood cell production.
Association Beyond TRMA: Studies show an association between B1 deficiency and anemia in certain groups, like hospitalized elderly patients, potentially due to shared malabsorption issues.
Treatment is Effective: In cases of TRMA, the associated anemia can be successfully treated with high-dose thiamine supplementation, though other symptoms like deafness may not improve.
Dietary Prevention: Maintaining a balanced diet rich in thiamine is the best preventative measure against general B1 deficiency, although genetic conditions require specific medical management.

The Core Connection: Thiamine-Responsive Megaloblastic Anemia (TRMA)

For the vast majority of people, a simple B1 deficiency does not lead directly to a specific anemia. The most direct and understood connection between B1 (thiamine) deficiency and anemia is a rare, inherited genetic disorder known as Thiamine-Responsive Megaloblastic Anemia (TRMA) syndrome.

TRMA is an autosomal recessive condition, meaning a person must inherit two mutated copies of the responsible gene to develop the syndrome. The condition is caused by a mutation in the SLC19A2 gene, which encodes for a protein that transports thiamine into cells. When this transporter is defective, cells, particularly those in the bone marrow, pancreas, and inner ear, cannot properly absorb thiamine.

This cellular thiamine deficiency directly impairs hematopoiesis, the process of forming blood cells. The result is megaloblastic anemia, a condition characterized by abnormally large red blood cells that are immature and dysfunctional. This syndrome often presents in infancy or adolescence and is part of a triad of symptoms, including diabetes mellitus and progressive sensorineural deafness.

The Role of Vitamin B1 in Red Blood Cell Production

To understand why a severe thiamine deficit can lead to problems with blood cells, it is important to know B1's role in the body. Thiamine, in its active form thiamine diphosphate (TDP), is a crucial coenzyme for several metabolic pathways. For hematopoiesis, its most relevant function is in the pentose phosphate pathway (PPP).

The Impact of Thiamine on Hematopoiesis

Energy Metabolism: TDP is a cofactor for enzymes involved in the Krebs cycle and energy production. Rapidly dividing cells, like red blood cell precursors in the bone marrow, have high energy demands.
Nucleic Acid Synthesis: TDP is required for the activity of transketolase, a key enzyme in the PPP. The PPP produces ribose-5-phosphate, a critical building block for DNA and RNA synthesis. Without sufficient thiamine, this process is impaired, leading to defective red blood cell maturation and megaloblastic anemia.
Antioxidant Properties: Thiamine also helps reduce oxidative stress, which can damage DNA. By mitigating oxidative stress, it indirectly supports the integrity of red blood cell precursors.

Potential Links Beyond Rare Genetic Disorders

Even in individuals without TRMA, research suggests a possible association between general vitamin B1 deficiency and anemia, though the link is often indirect or related to other underlying issues. For instance, a 2023 study found that anemia was significantly associated with B1 deficiency in hospitalized elderly patients. The researchers hypothesized that poor gastrointestinal function, which can lead to malabsorption of B1, might also impact the absorption of other key nutrients like B12 and iron, compounding the issue.

Conditions that can lead to B1 deficiency and may be present in individuals with anemia include:

Chronic alcoholism, which impairs both B1 and B12 absorption.
Malnutrition due to restrictive diets, anorexia, or food insecurity.
Gastrointestinal surgeries, such as gastric bypass, that reduce the area for nutrient absorption.
Long-term use of certain diuretics.

Differentiating Anemia Types

It is vital to distinguish between anemia caused by a specific genetic thiamine issue and other more common nutritional anemias. While TRMA causes a thiamine-responsive megaloblastic anemia, other deficiencies cause distinct types. The following table highlights key differences:


Feature	B1-Responsive Anemia (TRMA)	B12-Deficiency Anemia	Iron-Deficiency Anemia
Primary Cause	Genetic defect affecting thiamine transport into cells.	Poor B12 intake or malabsorption (often due to intrinsic factor issues like pernicious anemia).	Inadequate iron intake, poor absorption, or blood loss.
Anemia Type	Megaloblastic with ringed sideroblasts.	Megaloblastic.	Microcytic (small red blood cells).
Associated Symptoms	Diabetes, deafness, heart issues.	Neurological symptoms (tingling, numbness, balance issues).	Pica, fatigue, brittle nails, sore tongue.
Diagnostic Markers	Bloodwork shows macrocytic anemia, normal B12/folate levels, confirmed by genetic testing or thiamine response.	Low serum B12, high MCV (mean corpuscular volume).	Low hemoglobin, low ferritin, small MCV.
Treatment	Lifelong high-dose thiamine supplementation.	B12 injections or high-dose oral supplements.	Iron supplements and dietary changes.

Diagnosis and Management

Diagnosis of a B1-related anemia, especially the rare TRMA, is based on a patient's clinical symptoms and response to thiamine treatment. In cases of TRMA, anemia and other associated symptoms may improve with high-dose thiamine supplementation, although conditions like deafness may not be reversible. For suspected B1 deficiency, particularly in at-risk populations like those with alcoholism or poor diet, a healthcare provider might check transketolase activity in red blood cells, as this enzyme relies on thiamine to function.

Management of thiamine deficiency involves supplementation and addressing the underlying cause. High-dose oral or intravenous thiamine is used for severe deficiency, like that seen in Wernicke-Korsakoff syndrome, which can have neurological complications. Ensuring a balanced, healthy diet is the primary preventative measure.

For more information on vitamin B1 and its functions, refer to authoritative sources like the National Institutes of Health.(https://www.ncbi.nlm.nih.gov/books/NBK482360/)

Conclusion

While nutritional deficiencies of vitamin B1 are rarely a direct cause of anemia in the general population, a definitive link exists through the genetic disorder TRMA. This rare condition disrupts thiamine transport, leading to a specific type of megaloblastic anemia that is responsive to thiamine supplementation. Furthermore, broader systemic issues like chronic alcoholism or malabsorption can create both B1 deficiency and anemia, suggesting a complex interplay between nutritional health and blood cell function. Awareness of these specific connections is crucial for accurate diagnosis and effective treatment, ensuring that patients with symptoms of anemia are evaluated for all potential underlying nutritional causes, both common and rare.

Frequently Asked Questions

While it is not a common cause in the general population, low B1 levels can cause anemia in individuals with the rare genetic disorder TRMA. In some cases, poor B1 absorption linked to other health conditions can contribute to overall anemia.

TRMA is a rare genetic disorder where the body cannot effectively transport vitamin B1 into cells due to a gene mutation. This leads to a form of megaloblastic anemia that can be treated with high doses of thiamine.

Vitamin B1, in its active form, is a crucial coenzyme in metabolic pathways, including the pentose phosphate pathway. This pathway produces building blocks necessary for DNA and RNA, which are essential for red blood cell development. A deficiency disrupts this process, leading to improperly formed red blood cells.

No, B1 deficiency is a significantly rarer cause of anemia than deficiencies in iron or vitamin B12. Iron deficiency is the most common type of anemia, and B12 deficiency is a frequent cause of megaloblastic anemia.

The symptoms of a severe B1 deficiency, known as beriberi, include fatigue, irritability, loss of appetite, and neurological issues like impaired memory or confusion. Wet beriberi also affects the cardiovascular system, potentially causing heart failure.

Diagnosis involves evaluating clinical symptoms and blood tests. For TRMA, genetic testing can confirm the diagnosis, and a positive response to thiamine treatment is a key indicator. For other potential B1 deficiencies, doctors may test red blood cell transketolase activity.

Populations at higher risk include chronic alcoholics, elderly individuals with poor nutrition, people who have undergone certain gastrointestinal surgeries, and those with specific genetic disorders like TRMA.

Yes, high-dose oral thiamine supplementation can correct the megaloblastic anemia associated with TRMA. However, it may not reverse other symptoms of the syndrome, such as sensorineural hearing loss.