Vitamin B1 Deficiency

Thiamine deficiency is primarily caused by inadequate or poor nutritional intake, excessive alcohol consumption, or the patient belonging to special populations of individuals such as pregnant women, bariatric surgery patients, and anyone who has poor nutritional status. It is observed that Vitamin B1 deficiency is common specifically in diets, which comprise polished rice and grains mainly.

What is Vitamin B1?

Vitamin B1 is the first vitamin identified many years ago. It is also known as thiamine, which is one of the eight essential B-complex and is classified as a water-soluble B vitamin. Thiamine mainly exists in free form as a mono-, di- or triphosphate.

It is a very important nutrient that plays a crucial role in maintaining proper cellular function and promotes energy metabolism by converting carbohydrates into energy. Studies show that vitamin B1 plays a significant role in the proper functioning of nerves, muscles, and the heart. It propagates the nerve impulses and contributes to myelin sheath maintenance.

Vitamin B1 Mechanism of Action

Vitamin B1 functions as a catalyst in the generation of energy through decarboxylation of branched-chain amino acids and alpha-ketoacids and acts as a coenzyme for transketolase reactions in the form of thiamine pyrophosphate.

It also acts as a coenzyme in the metabolism process of carbohydrates. It is involved in the decarboxylation of pyruvate to acetyl-CoA, which is a critical step in the Krebs cycle and helps in energy production. Thiamine diphosphate (TDP) is the active form of thiamine which acts as a cofactor for several enzymes involved in the energy production process. This coenzyme function is crucial for the metabolism of sugars and amino acids.

The main work of these enzymes is to convert glucose into ATP, which is the primary energy currency of cells. Studies show that adequate ATP levels are necessary for the proper functioning of neurons, which as a result helps in the synthesis of neurotransmitters. However, insufficient thiamine levels disturb the energy production of the brain, which interrupts neural function and results in mood disturbances.

Vitamin B1 helps synthesize many important neurotransmitters, such as acetylcholine, which is a neurotransmitter critical for memory and learning. Thiamine-dependent enzymes contribute to the production of acetyl-CoA, which is a precursor for acetylcholine synthesis.

In addition to this, thiamine plays a role in the metabolism of glutamate to GABA, an inhibitory neurotransmitter. It has been concluded that a proper balance between excitatory (glutamate) and inhibitory (GABA) neurotransmitters is very essential for mood regulation.

However, vitamin B1 deficiency can disrupt this balance, which leads to increased glutamate activity (excitotoxicity) and decreased GABA activity, which may cause stress, anxiety, irritability, and depression.

Natural Sources of Vitamin B1

It has been concluded that during evolutions, most of the animals have lost the ability to synthesize vitamin B1 and this is the main reason why vitamin B1 is required in the diet.

Also, the synthesis of thiamine requires a lot of energy and resources, which is difficult for an animal’s metabolism to provide. It was found that vitamin B1 is present in its free in food sources as thiamine pyrophosphate (TPP).

TPP is considered to be the active form after being phosphorylated in the body. The conversion to TPP occurs primarily in the liver. After ingestion, it gets absorbed in the small intestine through active transport at low concentrations and passive diffusion at higher concentrations.

Some of the natural sources of vitamin B1 are mentioned below:

  • Brown Rice- It is a whole grain that retains the bran and germ. It is very healthy and contains a good amount of vitamin B1. It can be a good alternative to white rice.
  • Lentils- These are legumes that are very rich in thiamine and other essential nutrients like protein and fiber. People used to make soups out of it.
  • Sunflower Seeds- Sunflower seeds are a very convenient and common source of vitamin B1. It can be eaten raw, roasted, or as a salad in the meals.
  • Lean Pork- It is an animal source of vitamin B1. It is also rich in protein and other B vitamins, making it a nutritious addition to a balanced diet.
  • Tuna- It is a type of fatty fish. It contains many important nutrients, including vitamin B1. Healthcare providers recommend it for severe deficiencies.
  • Spinach- It is good for vegans, spinach is very high in thiamine and other vitamins like A, C, and K. It can be eaten raw in salads, steamed, or can be added in many other dishes.
  • Oranges- Oranges are a citrus fruit, which is famous for vitamin C, but yes it is very rich in vitamin B1 and fiber also.
  • Fortified Breakfast Cereals- These cereals are fortified with thiamine and other essential vitamins and minerals. They instantly boost the nutrients in the body. It can be consumed with milk or yogurt.

A balanced diet is really very necessary, which incorporates all important nutrients, so involving the above natural sources in the diets can help in overcoming vitamin B1 deficiency by maintaining an adequate level in the body.

What is Vitamin B1 Deficiency?

Vitamin B1 deficiency means that the body doesn’t have enough level of vitamin B1 in the body to maintain overall health including the maintenance of the cardiovascular system, nervous system, and many other important functions.

Usually, deficiency symptoms start to appear when vitamin B1 stores are depleted (which takes about 4 weeks after stopping intake). This condition is also known as beriberi. Beriberi can be further classified into two main types: wet beriberi, which mainly affects the cardiovascular system, and dry beriberi, which affects the nervous system. If this condition remains untreated, it can lead to many complications and can cause death.

Dry beriberi include impaired reflexes and symmetrical motor and sensory deficits in the extremities. In this condition, the myelin sheath gets disrupted but without any acute inflammation. Wernicke encephalopathy is another variation of dry beriberi where there are symptoms of nausea and vomiting, followed by horizontal nystagmus, ocular nerve palsy, fever, ataxia, and progressive mental impairment, eventually leading to the Korsakoff syndrome.

Wet beriberi involves heart function failures which can lead to edema and fluid retention. The key reason for heart dysfunction is an overuse injury. Wet beriberi is a serious medical emergency that can lead to death in no time if left untreated.

Does Vitamin B1 Deficiency Cause Depression?

Recent studies show that vitamin B1 deficiency could influence memory function, and cognitive impairment and can result in dementia. Vitamin B1 is considered to be very essential for neuronal function and deficiencies have been linked to depression.

From the above section, it can be easily concluded that vitamin B1 plays a crucial role in brain function such as the production of neurotransmitters. And its deficiency can disrupt all these functions including mood regulation, as there would be a fall in the levels of dopamine and serotonin in the body which can lead to depression.

Vitamin B1 Deficiency Causes

Vitamin B1 is really very important for the body to function properly and studies show that populations rely heavily on polished rice or highly processed carbohydrates which do not have enough vitamin B1 content.

Apart from this pregnant and breastfeeding women are very vulnerable to deficiencies because their body needs high levels of thiamine, which is not usually present in meals in high quantity. It becomes essential to consume enough level of vitamin B1.

Recommended Daily Intake of Vitamin B1

The recommended daily intake (RDI) of Vitamin B1 varies by age, gender, and life stage:

  • Infants (0-6 months): 0.2 mg
  • Infants (7-12 months): 0.3 mg
  • Children (1-3 years): 0.5 mg
  • Children (4-8 years): 0.6 mg
  • Children (9-13 years): 0.9 mg
  • Teens (14-18 years): 1.2 mg (males), 1.0 mg (females)
  • Adults (19+ years): 1.2 mg (males), 1.1 mg (females)
  • Pregnant and Breastfeeding Women: 1.4 mg

Some of the causes of vitamin B1 deficiency are mentioned below:

  • Inadequate Dietary Intake- It is well known that vitamin B1 can not be produced in the body on its own, so it is very important to consume it from dietary sources in enough quantity. Consuming diets that are low in thiamine-rich foods, such as whole grains, legumes, nuts, and seeds, can lead to a deficiency in vitamin B1.

  • Chronic Alcoholism- Excessive alcohol intake can also cause vitamin B1 deficiency, studies show that alcohol interferes with the absorption of thiamine in the gastrointestinal tract and impairs the body’s ability to store the vitamin in the liver.
  • Malabsorption Syndromes- There are some medical conditions that impair the digestive tract absorption ability, due to which many important nutrients are not absorbed including vitamin B1. For example; Crohn’s disease, celiac disease, and chronic diarrhea.
  • Prolonged Starvation or Anorexia-Individuals with eating disorders like anorexia nervosa often consume very limited amounts of food, because they have a fear of gaining weight so they eat very less, which drastically reduces their intake of essential nutrients, including thiamine to the loss of water-soluble vitamins, including thiamine, from the blood.
  • Certain Medical Conditions- There are some conditions that alter the metabolism process increase the body’s nutritional requirements and can lead to vitamin B1 deficiency. For example; HIV/AIDS, and hyperthyroidism.
  • Increased Metabolic Demand- There are certain conditions in which the body demands higher levels of nutrients. Such as pregnant and breastfeeding women, have higher metabolic rates to support fetal growth and milk production, so if they are not getting enough nutrients through diet, they are at risk of developing vitamin B1 deficiency.
  • Genetic Disorders- Some genetic conditions can impair the body’s ability to transport, store, or utilize thiamine, which can lead to a functional deficiency even if dietary intake is adequate.

Alcohol and Vitamin B1 Deficiency

Vitamin B1 deficiency is found to be common in people who drink excessive amounts of alcohol. A survey concludes that up to 80% of people with an addiction to alcohol develop thiamine deficiency. That means excessive alcoholism can cause vitamin B1 deficiency in the body.

Alcohol causes inflammation of the stomach lining and digestive tract, which affects the absorption ability of the gastrointestinal tract. It interrupts the absorption of thiamine and affects the process of conversion to an active form. In severe cases, chronic alcohol consumption can also impair liver function, which further contributes to the reduction of thiamine storage and metabolism, and leads to severe deficiency-related conditions like Wernicke-Korsakoff syndrome.

How to Test for Vitamin B1 Deficiency?

Testing for vitamin B1 deficiency is very important because it is involved in crucial processes of the body. It is very essential for carbohydrate metabolism and neural function. Early detection can help in preventing irreversible damage and will promote speedy recovery.

A combination of clinical evaluation and laboratory tests are used to detect vitamin B1 deficiency. The key diagnostic tools involve the detection of blood thiamine levels, erythrocyte transketolase activity, and urine thiamine excretion.

Some of the testing processes are mentioned below:

  • Clinical Evaluation-
    Medical History: In this process all the symptoms are reviewed and analyzed, such as fatigue, irritability, confusion, muscle weakness, and heart issues. It is observed that why thiamine is not getting absorbed in the body.
    Physical Examination: In physical examinations, all physical signs are noted, such as muscle weakness, peripheral neuropathy, cardiovascular symptoms, and neurological abnormalities.
  • Laboratory Tests-
    Blood Thiamine Level:
    Sample Collection: At first the blood is collected from a vein for the testing process.
    Measurement Methods: Thiamine levels are checked using High-Performance Liquid Chromatography (HPLC) or other enzymatic assays.
    Forms of Thiamine: Thiamine in the blood can be measured in its active form which is thiamine diphosphate (TDP). It is an active coenzyme also.
    Thiamine Pyrophosphate (TPP) in Red Blood Cells:
    This test is mainly used to measure the concentration of TDP within red blood cells, providing a more accurate reflection of the body’s thiamine status over time compared to plasma thiamine levels.
    Erythrocyte Transketolase Activity:
    Sample Collection: In this process, a blood sample is taken to isolate red blood cells.
    Enzyme Activity Measurement: Transketolase is found to be a thiamine-dependent enzyme. The activity of this enzyme in red blood cells is measured before and after adding thiamine pyrophosphate.
    Activation Coefficient: It is a ratio ratio of enzyme activity after and before the addition of thiamine. An activation coefficient (AC) >1.25 indicates thiamine deficiency.
  • Urine Thiamine Excretion-
    Sample Collection: In this process, the urine sample is collected to measure the thiamine in blood.
    Measurement: Now the thiamine amount excreted in urine is measured. If there are low thiamine levels in the urine it indicates a vitamin B1 deficiency. indicate a deficiency because the body conserves thiamine when deficient.

In the last process, results are interpreted:

  • Normal Range- Blood thiamine levels typically range from 2.5 to 7.5 micrograms per deciliter (µg/dL).
  • Deficiency- Levels below the normal range, a high erythrocyte transketolase activation coefficient, or low urinary excretion confirm thiamine deficiency.

Symptoms of Vitamin B1 Deficiency

  • Fatigue and Weakness
  • Loss of Appetite
  • Beriberi (Dry and Wet)
  • Weight Loss
  • Muscle Pain
  • Rapid heart rate

Psychiatric Symptoms Vitamin B1 Deficiency

  • Depression
  • Irritability
  • Confusion
  • Memory Loss
  • Anxiety
  • Agitation
  • Hallucinations
  • Confabulation

Psychiatric Illness Exacerbated by Vitamin B1 Deficiency

  • Depression
  • Anxiety Disorders
  • Schizophrenia
  • Bipolar Disorder
  • Wernicke’s Encephalopathy
  • Korsakoff’s Psychosis

Medical Illness Exacerbated by Vitamin B1 Deficiency

  • Heart Failure
  • Diabetes Mellitus
  • Alzheimer’s Disease
  • Chronic Fatigue Syndrome
  • Alcohol Use Disorder

Consequences of Vitamin B1 Deficiency

Vitamin B1 deficiency affects the overall well-being, from the debilitating effects of beriberi to severe neurological dysfunction. Some of the vitamin B1 deficiency consequences are mentioned below:


Beriberi is found to be connected to Vitamin B1 deficiency, it is of two types: wet beriberi and dry beriberi. As it was discussed earlier; Wet beriberi affects the cardiovascular system and Dry beriberi affects the nervous system. It happens due to the deficiency of thiamine in the blood, which in turn disrupts the carbohydrate metabolism. All these lead to the accumulation of pyruvate and lactate (the main reason for heart and nerve damage).

Wernicke-Korsakoff Syndrome

It is a very serious neurological disorder caused due to chronic thiamine deficiency, which was found to be associated with alcoholism. Its symptoms are confusion, ataxia (loss of coordination), and ophthalmoplegia (paralysis of the eye muscles). It requires treatment on time if left untreated can lead to Korsakoff’s psychosis. This condition arises due to neuronal damage.

Peripheral Neuropathy

When peripheral nerves are damaged due to severe thiamine deficiency, it is termed peripheral neuropathy. Its symptoms comprise tingling, numbness, burning sensations, and pain in the hands, palms, and feet, which gradually spreads to all other parts of the body. As thiamine is involved in the process of nerve function, or the production of neurotransmitters, its deficiency impairs all these functions.

Cardiovascular Problems

Vitamin B1 deficiency can lead to severe cardiovascular issues beyond wet beriberi. Studies show that vitamin B1 is also involved in the metabolism of myocardial energy but in its deficiency, this process gets disrupted, which can result in cardiac dysfunction. Its symptoms can be identified as chest pain, and congestive heart failure, which can be life-threatening.

Mental Health Issues

Vitamin B1 deficiency has been linked to mental health issues which can include depression, anxiety, or other problems. It is well known that thiamine is involved in the process of neurotransmitter production, such as serotonin and dopamine which work as mood regulators. But in vitamin B1 deficiency, these neurotransmitters are not released properly which affects the mood and causes mental health problems.

Vitamin B1 Deficiency Treatment

Treatment of vitamin B1 deficiency is very crucial as it is involved in many important functions of the body, usually eating a diet rich in thiamine can help in maintaining adequate thiamine stores in the body. But in severe cases instant relief is important, so some of the treatment options are mentioned below:

Thiamine Supplements

Taking thiamine supplementation is the best option which is highly recommended in severe cases. Most important is its ease of administration, it can be taken orally or intravenously, depending on the severity of the deficiency. Oral supplements can be effective in mild to moderate deficiency and prescribed dose can range between 50 to 100 mg daily.

But in severe cases, such as Wernicke-Korsakoff syndrome, high-dose intravenous thiamine is necessary, with initial doses ranging from 200 to 500 mg, which needs to be administered several times daily.

Dietary Modifications

No matter how many supplements or medicines are consumed, diet is the most important of all. Dietary changes are essential so that thiamine levels can be maintained for the long term. Including thiamine in the diet can prevent the recurrence of deficiency. Such as whole grains, legumes, nuts, seeds, pork, and fortified cereals. A balanced diet is necessary to maintain thiamine levels.

Treatment of Underlying Conditions

It is important to identify underlying conditions that contribute to vitamin B1 deficiency. There are some conditions that promote vitamin B1 deficiency, such as chronic alcoholism, gastrointestinal diseases, and malabsorption syndromes. These condition impairs the gastrointestinal tract and disrupts the absorption process. So, treatment of these conditions is very essential. It ensures a more comprehensive and lasting resolution of the deficiency.

Monitoring and Follow-Up

Taking treatment is good but monitoring it is more important. It is essential to follow up to ensure the effectiveness of the treatment as it will prevent the recurrence of deficiency. Follow up process includes regular checkups, and consulting health care specialists on a regular basis.

Continuous monitoring is really important for those individuals with chronic conditions that predispose them to thiamine deficiency. And with the help of regular check-ups, it would be very easy for healthcare providers to detect any problem beforehand.

Supplements for Vitamin B1 Deficiency

Treatment of vitamin B1 deficiency involves a variety of supplementation methods. And by incorporating these treatment options in patients’ life, can rapidly restore their thiamine levels and maintain long-term health.

Thiamine supplements are available in various forms, which include tablets, capsules, and injections. These are mainly prescribed to individuals who are suffering from severe vitamin B1 deficiency. Mainly doses are defined on the basis of severity of deficiency.

It is true that vitamin B1 deficiency can lead to serious health issues including mental health problems but it can be treated with the help of supplements.

A crucial fact is that oral or injectable thiamine supplements can rapidly reverse deficiency symptoms and prevent long-term damage when administered promptly.

Oral Thiamine Supplements

Oral thiamine supplements are prescribed in the beginning when deficiency is nt very severe. These supplements are available in various forms, including tablets, capsules, and powders. Recommended doses range from 50 to 100 mg per day, depending on the severity of the deficiency and the patient’s specific needs.

Oral supplements are preferred because these can be well-absorbed and can effectively replenish thiamine levels when taken consistently. They are convenient and non-invasive, making them a preferred option for many patients. Regular use of oral supplements can help in preventing the recurrence of vitamin B1 deficiency.

Intravenous (IV) Thiamine Administration

These are mainly prescribed for severe thiamine deficiency such as Wernicke-Korsakoff syndrome, supplementation can be done intravenously for instant relief. IV thiamine is typically given in high doses, ranging from 200 to 500 mg several times daily. This method ensures rapid delivery of thiamine directly into the bloodstream, providing immediate relief of symptoms and preventing further neurological damage.

Intravenous administration is often followed by a maintenance dose, which can be given orally once the acute phase is managed. This approach is critical in emergency situations and for patients who cannot absorb oral thiamine effectively due to gastrointestinal issues.

Intramuscular (IM) Thiamine Injections

In recent days Intramuscular thiamine injections are also widely used, especially for patients who cannot tolerate oral supplements or require rapid replenishment but do not need IV administration. IM injections are typically given in doses of 100 mg daily until deficiency symptoms improve.

This method is less invasive than IV administration but still allows for faster absorption compared to oral supplements. IM injections can be administered by healthcare professionals or, in some cases, by patients themselves after proper training. This option provides flexibility in managing thiamine deficiency outside of hospital settings.

Toxicity from Vitamin B1 Supplementation

Studies show that excessive supplementation of vitamin B1 can lead to toxicity, but the fact is thiamine is generally considered safe even at high doses. As it is a water-soluble vitamin, if it is in excess, the body will automatically remove it through urine in the excretion process. However, extremely high doses can still cause adverse effects, some are mentioned below:

Nausea and Vomiting

Vomiting is considered to be an uncontrollable reflex that expels the contents of the stomach through the mouth. Sometimes it happens due to food poisoning or when the body wants to remove unwanted content out of the body. Nausea is a state where an individual feels like throwing up but isn’t actually vomiting.

Hypersensitivity Reactions

Skin rashes and itching, A hypersensitivity reaction occurs when the body produces an unnecessary and undesirable immune response following exposure to a certain antigen. Many people refer to hypersensitivity as a form of allergy.


Low blood pressure, Hypotension is the medical term for low blood pressure. You have it when a reading shows your blood pressure is much lower than expected. Hypotension is a decrease in systemic blood pressure below accepted low values.

Methods to Avoid Toxicity from Vitamin B1 Supplementation

Although thiamine toxicity is not very dangerous for the body, it is always good to avoid such happenings. Some of the methods to avoid toxicity from vitamin B1 supplementation are mentioned below:

Discontinuation of Supplements

Discontinuing the intake of thiamine supplements can be considered one of the best options to avoid toxicity. This will naturally eliminate any excess thiamine. In severe toxicity, it is advised to consult a healthcare provider.

Supportive Care

Supportive care is necessary for individuals experiencing symptoms of thiamine toxicity. Supportive care includes regular monitoring of whether everything is in control, administering fluids, and providing symptomatic relief. The body automatically prepares itself to eliminate excessive thiamine from the body, supportive care could help in this process.

Symptomatic Treatment

Symptomatic treatment includes the management of some specific symptoms of thiamine toxicity. In this medication or dietary changes may be prescribed to alleviate the symptoms. Some conditions such as such as allergic reactions or neurological disturbances require specific interventions based on their severity and impact on the patient’s health.

Monitoring and Follow-Up

After the initial treatment of thiamine toxicity, monitoring and follow-up are essential to ensure that the body has successfully eliminated the excess thiamine and that symptoms have resolved. This may involve regular blood tests to check thiamine levels are in control.

Prevention of Future Toxicity

Future toxicity can be avoided by regular check-ups and continuous consumption of supplements, as per the healthcare provider’s instructions. Avoid overdose of supplements. Avoiding excessive doses and monitoring thiamine levels regularly can help prevent accidental overdose. It is important to acknowledge early signs of toxicity, to avoid further complications.

In conclusion, it can be concluded that vitamin B1 is essential for energy metabolism and overall health. Its deficiency can disrupt many important functions of the body, including physical and mental health issues. However, appropriate supplements and a balanced diet can help in maintaining the thiamine levels in the body.

Early diagnosis and treatment are crucial to prevent long-term complications and ensure optimal health. But in severe cases, one must consult a healthcare provider as soon as possible. Until then, we’re here to help with all the important knowledge you need!

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Fact Checked by
- Dr. Gundu Reddy
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