Thiamine Deficiency: Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is thiamine deficiency?
Thiamine deficiency is a lack of vitamin B1, which the body needs for cell function, growth and turning food into energy. Low levels can affect the heart, immune system and nervous system, and severe deficiency is called beriberi. It can result from poor nutrition, reduced absorption or certain medicines. Treatment with foods, supplements or injections can reverse it. [1]
What the research says
Thiamine deficiency is most common in the first months after bariatric surgery. A meta-analysis of 41 studies found a pooled prevalence of 7% before surgery (95% CI 4–12%), then 19% at 3 months (a very wide range, 0–68%), 9% at 6 months and 6% at 1 year (Karimi Behnagh et al., Obes Surg, 2024). [2]
Nerve weakness from thiamine deficiency can respond quickly to treatment. In a prospective study of 41 adults with unexplained weakness in a region where polished rice is a staple, 25 responded to a thiamine challenge, with clinical improvement within 24 hours, although proximal muscle weakness persisted longer (Nisar et al., Eur J Neurol, 2024). [3]
Under-treatment is common when thiamine deficiency complicates severe vomiting in pregnancy. A systematic review of 146 case reports (177 cases of Wernicke’s encephalopathy in hyperemesis gravidarum) found subtherapeutic thiamine dosing in 63.6% and chronic cognitive disorders in 65.4% (Oudman et al., Eur J Obstet Gynecol Reprod Biol, 2019). [4]
What does thiamine do in the body?
Thiamine is essential for normal cell function, growth, and development. It also helps the body convert food into energy. [1]
When thiamine levels remain low, the heart, immune system, and nervous system may be affected. Fatigue, appetite loss, and nerve damage can begin in as little as three weeks in some cases. [1]
What are the symptoms of thiamine deficiency?
Symptoms of low thiamine can be vague and may mimic other conditions. Possible symptoms include fatigue, irritability, loss of appetite, nausea, vomiting, confusion, delirium, mental impairment, and short-term memory problems.
Some people develop balance issues, blurred vision, hallucinations, or tingling and burning in the arms and legs. Tell a healthcare provider if you develop any of these symptoms so the cause can be investigated. [1]
Symptom group | Possible symptoms |
Energy and appetite | Fatigue and loss of appetite. |
Thinking and memory | Confusion, delirium, mental impairment, hallucinations, and short-term memory issues. |
Balance and vision | Balance issues and blurred vision. |
Digestive symptoms | Nausea and vomiting. |
Nerve symptoms | Tingling or burning in the arms and legs. |
Mood and behavior | Irritability and changes that may be related to mental impairment. |
Can thiamine deficiency cause nerve symptoms?
Yes. Thiamine deficiency can cause tingling and burning in the arms and legs, and severe cases can cause nerve damage. Nerve damage may be permanent when deficiency is severe or untreated. [1]
Can thiamine deficiency affect the heart or brain?
It can. Persistent deficiency may affect the heart and nervous system. Possible complications include congestive heart failure, brain damage called encephalopathy, cognitive impairment, loss of coordination, memory loss, coma, and muscle atrophy.
What causes thiamine deficiency?
Thiamine deficiency can happen when the body needs more thiamine, cannot metabolize it properly, cannot absorb enough of it, or does not receive enough through food. [1]
Conditions that can increase thiamine needs include hyperthyroidism. Liver disease can disrupt thiamine metabolism, while chronic diarrhea can interfere with absorption. Certain diuretics, cardiovascular drugs, and antiseizure medicines may also contribute. [1]
A diet based mainly on highly processed carbohydrates such as white rice, white sugar, and white flour may provide too little thiamine. Severe anorexia nervosa can contribute because of limited food intake. [1]
Who is at risk for thiamine deficiency?
Thiamine deficiency is uncommon, but some conditions and circumstances raise the risk. Risk factors include alcohol use disorder, kidney disease, lack of access to nutritious foods, poor diet or starvation, and previous gastric bypass surgery.
Congenital beriberi means a baby is born without the ability to absorb thiamine. Babies who drink breast milk from a parent with thiamine deficiency also have a higher risk. [1]
Wernicke-Korsakoff syndrome is a memory disorder linked to thiamine deficiency and alcohol use disorder. A provider can help determine whether symptoms and risk factors require testing or treatment. [1]
Risk factor or situation | Why it matters |
Alcohol use disorder | A recognized risk factor, and linked with Wernicke-Korsakoff syndrome. |
Kidney disease | May increase the risk of low thiamine. |
Gastric bypass surgery | Can affect how nutrients are absorbed. |
Poor diet or starvation | Reduces the amount of thiamine available from food. |
Limited access to nutritious foods | Makes a balanced thiamine intake more difficult. |
Certain health conditions or medicines | May increase needs, disrupt metabolism, or impair absorption. |
Breastfeeding with parental deficiency | Can increase a baby’s risk. |
What complications can thiamine deficiency cause?
Untreated thiamine deficiency can lead to serious and potentially life-threatening complications. These may include brain damage, cognitive impairment, coma, congestive heart failure, loss of coordination, memory loss, muscle atrophy, and nerve damage.
Nerve damage can be permanent in severe cases. The risk of complications is one reason new or troubling symptoms should be assessed rather than managed with self-diagnosis alone. [1]
How is thiamine deficiency diagnosed?
A healthcare provider will perform a physical examination and check for obvious symptoms. They will also run blood tests to help confirm a diagnosis. [1]
Providers cannot directly measure the level of thiamine in your blood. But they can check the activity of an enzyme called transketolase. Transketolase needs thiamine to work, so low activity on a blood test can point to a lack of thiamine. [1]
Diagnosis also involves considering the person’s symptoms, medical history, nutrition, possible absorption problems, medicines, and other conditions that could explain similar symptoms.
How do you treat thiamine deficiency?
The way to correct low thiamine is to restore thiamine to the body. Adults need about 1.1 to 1.2 milligrams of thiamine each day, although individual needs and treatment plans vary. [1]
Some people can meet their needs through food. Severe deficiency may require supplements or medically supervised treatment to replenish the body’s stores. [1]
Thiamine-rich foods
Food sources of thiamine include black beans, lentils, pork, salmon, mussels, macadamia nuts, sunflower seeds, whole-wheat bread, yogurt, and enriched or fortified white carbohydrates such as rice, bread, and flour.
Food group | Examples |
Beans and legumes | Black beans and lentils. |
Meat and seafood | Pork, salmon, and mussels. |
Nuts and seeds | Macadamia nuts and sunflower seeds. |
Grains and breads | Whole-wheat bread and enriched or fortified rice, bread, and flour. |
Dairy | Yogurt. |
Food choices should be adapted to a person’s overall health, dietary needs, and access to nutritious foods. Food alone may not be enough when deficiency is severe.
Thiamine supplements
Over-the-counter options can include multivitamins or vitamin B-complex formulas. A severe deficiency may require a higher dose under medical supervision.
Depending on the situation, a provider may use tablets, injections, or IV infusions. Do not assume that an over-the-counter supplement is an appropriate treatment for severe symptoms or a suspected deficiency. [1]
How long does it take to reverse thiamine deficiency?
Recovery depends on how severe the deficiency is and how long it has been present. Some heart symptoms may improve within the first few hours or days after treatment.
Nerve and motor symptoms can take up to six months to improve. In severe cases, nerve damage may be permanent. A healthcare provider can explain what to expect in an individual situation and continue supplementation until levels return to normal. [1]
What is the outlook?
When diagnosed and treated early, thiamine deficiency is reversible, and most symptoms should go away once thiamine levels return to normal. [1]
Severe or untreated deficiency can cause serious complications or death. Early evaluation is especially important when symptoms involve confusion, balance, memory, the nervous system, or the heart.
Can thiamine deficiency be prevented?
Prevention focuses on eating thiamine-rich foods and managing conditions that affect thiamine levels. Follow a provider’s recommendations and attend regular checkups when a health condition or treatment may affect nutrition or absorption. [1]
People with limited access to nutritious foods may need help identifying practical food options or discussing supplements with a qualified healthcare professional.
When should I see a healthcare provider?
See a healthcare provider any time you develop new or troubling symptoms. Fatigue, appetite loss, confusion, balance changes, memory issues, nausea, vomiting, or tingling and burning in the arms and legs can have many causes. [1]
Prompt evaluation can help identify thiamine deficiency or another condition and start appropriate treatment. Seek professional guidance rather than choosing high-dose supplements based only on symptoms.
What questions should you ask a healthcare provider about thiamine deficiency?
Useful questions about thiamine deficiency include whether symptoms relate to low thiamine, which tests are needed, which supplement form fits and how long recovery may take.
Could my symptoms be related to low thiamine?
Do I need blood tests or transketolase testing?
Could a medicine or health condition affect my thiamine level?
Would food be enough in my situation?
Which form of supplementation is appropriate?
How long might recovery take?
Conclusion: Low thiamine can be treated
Thiamine deficiency is a lack of vitamin B1 needed for cell function, growth, development, and energy production. It may cause vague symptoms such as fatigue and appetite loss, but it can also affect the nervous system, heart, immune system, memory, balance, and coordination. [1]
Risk can rise with alcohol use disorder, poor nutrition, kidney disease, gastric bypass surgery, absorption problems, certain medicines, and other health conditions. A provider may use an examination, blood tests, and transketolase activity to investigate the cause.
Early treatment can reverse deficiency. Food may help maintain healthy levels, while severe cases may require tablets, injections, or IV infusions under medical supervision. If you have new or troubling symptoms, professional evaluation is the safest next step. [1]
Frequently Asked Questions
What is thiamine deficiency?
Thiamine deficiency means the body does not have enough thiamine, or vitamin B1, to function properly. Severe thiamine deficiency is called beriberi.
What are early symptoms of thiamine deficiency?
Possible symptoms include fatigue, loss of appetite, nausea, vomiting, irritability, confusion, balance issues, memory problems, and tingling or burning in the arms and legs. Symptoms can be vague and may resemble other conditions.
Can thiamine deficiency cause nerve damage?
Yes. Low thiamine can cause nerve symptoms, and severe cases may lead to nerve damage. Some damage can be permanent.
What foods are high in thiamine?
Food sources include black beans, lentils, pork, salmon, mussels, macadamia nuts, sunflower seeds, whole-wheat bread, yogurt, and enriched or fortified white carbohydrates.
How much thiamine do adults need?
Adults need about 1.1 to 1.2 milligrams of thiamine each day. Individual needs and treatment plans should be discussed with a healthcare provider.
How is thiamine deficiency diagnosed?
A provider may perform a physical examination and blood tests. Providers can assess transketolase enzyme activity, because transketolase needs thiamine to function.
Can I treat thiamine deficiency with food alone?
Food may help maintain thiamine levels, but severe deficiency may require supplements or medically supervised tablets, injections, or IV infusions. A provider should guide treatment when deficiency is suspected.
How long does it take to recover?
Recovery depends on severity and duration. Some heart symptoms may improve within hours or days, while nerve and motor symptoms can take up to six months. Severe nerve damage may be permanent.
What is beriberi?
Beriberi is the term for severe thiamine deficiency.
When should I seek care?
See a healthcare provider whenever you develop new or troubling symptoms. Prompt evaluation is important because untreated deficiency can cause serious complications.
References
Cleveland Clinic. Thiamine Deficiency. Cleveland Clinic. Last updated November 21, 2024. https://my.clevelandclinic.org/health/diseases/thiamine-deficiency
Karimi Behnagh A, Eghbali M, Abdolmaleki F, et al. Pre- and post-surgical prevalence of thiamine deficiency in patients undergoing bariatric surgery: a systematic review and meta-analysis. Obes Surg. 2024;34(2):653-665. PMID 38095772. https://doi.org/10.1007/s11695-023-06896-6
Nisar S, Yousuf Wani I, Altaf U, et al. Thiamine deficiency-related neuropathy: a reversible entity from an endemic area. Eur J Neurol. 2024;31(3):e16155. PMID 38018774. https://doi.org/10.1111/ene.16155
Oudman E, Wijnia JW, Oey M, et al. Wernicke’s encephalopathy in hyperemesis gravidarum: a systematic review. Eur J Obstet Gynecol Reprod Biol. 2019;236:84-93. PMID 30889425. https://doi.org/10.1016/j.ejogrb.2019.03.006
Disclaimer
This article is for general educational purposes and is not a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition.
It is not a diagnosis, emergency protocol, prescription or individualized treatment plan. A qualified healthcare professional should evaluate personal symptoms, blood-test questions, medication effects, nutrition concerns and supplement decisions. No specific food or supplement can replace medical care for severe deficiency.
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