B1 Vitamin

B1 Vitamin or Thiamin is a kind of water-soluble vitamin that belongs to the vitamin B complex group. It was the first member of the vitamin B family isolated in 1926. Foods like poultry products, fortified cereals, nuts etc., are rich in thiamin content.

Dietary supplements are also available to fulfil the demand for vitamin B1 in our body and to cure thiamine deficiency and disorders like beriberi, Wernickle encephalopathy and Leigh syndrome. Thiamin is an essential micronutrient.

It plays a significant role in the metabolism, growth and proper functioning of the body cells. Thiamine is a coenzyme of Vitamin B1 that plays a pivotal role in nerve, muscle and heart function. Also, it enables our body to utilize carbohydrates as energy.

Thiamin has a short half-life. Therefore, our body needs a regular intake of thiamin rich foods, as the liver stores a minimal amount of thiamin. Thiamin diphosphate or thiamin pyrophosphate is a metabolically active form.

In this context, we will discuss the definition, food sources, dosage, absorption and dietary supplements of vitamin B1. In addition, the symptoms, risk factors associated with vitamin B1 have also been explained along with the diagnosis, treatment and functions.

Content: B1 Vitamin

  1. Definition
  2. Food Sources
  3. Dosage
  4. Absorption
  5. Dietary Supplements
  6. Thiamin Deficiency
  7. Functions
  8. Uses

Definition of B1 Vitamin

Vitamin B1, or thiamin, is a part of the vitamin B complex that exhibits heat-lability and water-solubility. Thiamin is an active coenzyme of the vitamin B1 complex that facilitates the metabolism of organic biomolecules through various biological pathways. It is also crucial for the functioning of the nervous and cardiovascular system.

PropertiesVitamin B1
Molecular formulaC12H17CIN4OS
Molecular weight300.81g/mol
Melting point164 degrees Celsius
SolubilityWater soluble
Half lifeShort
StabilityNon stable in neutral and alkaline solution

Vitamin B1 Foods

  • Vegetables: Cauliflower, potatoes, asparagus, kale, lettuce, spinach, tomatoes, squash etc.
  • Fruits: Oranges, apricots, watermelon, apples, etc., contains high vitamin B1 content.

Sources of vitamin B1

  • Poultry products: Mutton, pork, chicken, eggs etc.
  • Dairy products: Milk, curd, cheese etc.
  • Fortified grains and nuts: Rice, wheat, almonds, wall-nut etc.
  • Other sources: Brewer’s yeast and blackstrap molasses.

Dosage of B1 Vitamin

Recommended daily dosages of vitamin B-1 depend on age, gender, and other conditions like pregnancy. Recommended daily intake (RDI) for men and women are 1.2 mg/day and 1.1 mg/day, respectively.

Pregnant women require a higher dose of vitamin B-1, while infants require a lesser; both are based on the doctor’s prescription. If anyone is facing vitamin B-1 deficiency, then he/she must need to consume supplements.


The small intestine actively consumes or absorbs the thiamin from natural food sources. However, the small intestine passively uptake the dietary supplements of vitamin B1 at pharmacological doses.

Intestinal phosphatase in the small intestine hydrolyzes the nutritional supplements that are generally available in the phosphorylated form and liberates free thiamin.

After that, the liver primarily stores the free thiamin to a minimal extent, and the kidneys excrete the remaining through urine.

Dietary Supplements

The necessity of vitamin B1 or thiamin can also be fulfilled by incorporating dietary supplements as multivitamins or individual supplements. Thiamin monohydrate and thiamin hydrochloride are the two most common supplements that remain stable and water-soluble. Other than this, synthetic thiamin (Benfothiamin) is also available as a dietary supplement.

Thiamin Deficiency

It results from a low intake of thiamin rich foods and lower absorption capacity of the gut, and higher excretion rates of the kidneys.

Risk Factors

Vitamin B1 deficiency commonly occurs in the individuals like:

  1. Alcoholic patients: Ethanol minimizes the gastrointestinal absorption of thiamin that results in lowering the absorption of thiamin, and ultimately causes thiamin deficiency.
  2. Individuals with suppressed immunity: People suffering from malnutrition or diseases like HIV infection easily acquire diseases like beriberi and Wernicke-Korsakoff syndrome.
  3. People who take concomitant use of multiple medications leads to cause toxicity and low absorption of vitamin B.
  4. Diabetic patients: They are at higher risk of getting thiamin deficiency.
  5. Patients who have undergone bariatric surgery lack vitamin B1, according to the RBC transketolase activity.

Signs and Symptoms

  • Weight loss
  • Confusion
  • Irritability
  • Fatigue
  • Short term memory loss
  • Muscle weakness
  • Nausea and vomiting sensations
  • Tingling sensations
  • Slow heart rate and shortness of breath


Sometimes, vitamin B deficiency leads to cardiovascular diseases like enlarged heart, Beriberi and Wernicke-Korsakoff syndrome.

Beriberi is a clinical condition where an individual acquires impaired sensory, motor and reflex functions. Generally, it is characterized by peripheral neuropathy, which sometimes results in congestive heart failure, edema and finally, the death of a person.

Wernicke-Korsakoff syndrome predominantly occurs in alcoholic individuals, people with suppressed immunity and those already suffering from gastrointestinal disorders. The Wernicke-Korsakoff syndrome involves acute and chronic phase.

Wernicke’s encephalopathy is an acute phase, while Korsakoff’s psychosis represents a chronic phase. The first phase is a life-threatening phase and causes peripheral neuropathy. People who survived the early stage of the disease may develop Korsakoff’s psychosis, which causes mental disorders like short term memory loss, disorientation and confabulation.


The following two assays help in diagnosing vitamin B1 deficiency:

Assaying of transketolase enzyme activity: The transketolase activity depends upon the thiamin pyrophosphate, and the results obtained through this assay termed as “TDP or thiamin pyrophosphate effect“. The results are made by the extent of unsaturation of enzyme transketolase with the thiamin pyrophosphate.

In a healthy person, the TDP effect is between 0-15%. However, an individual with mild thiamin deficiency has a 15-25% TDP effect. The individuals with a TDP effect of more than 25% lack vitamin B1.

Assaying urinary thiamin excretion: Insufficient vitamin B1 intake is observed in people excreting thiamin less than 100 mcg/day. Extremely low intake of vitamin B1 is observed when the individuals excrete thiamin less than 40 mcg/day.


According to the WHO, administration of 10 mg thiamin for a week can treat mild vitamin B1 deficiency. However, it recommends intravenous administration of 25-30 mg in infants and 50-100 mg in adults in case of severe deficiency.

Then, it is followed by intramuscular administration of 10 mg vitamin B1 daily for one weak. The recommended dose varies from person to person, so you need to take a physician’s advice.

Functions of Thiamin

  1. Metabolism of macronutrients: Thiamin combines with the energy molecule adenosine triphosphate to form thiamin pyrophosphate or TPP.
    Thiamin pyrophosphate functions as an active cofactor that regulates the enzymatic activity of five enzymes that are participating in the catabolism of glucose, pyruvate, amino acids and lipids.
  2. Boosts Immunity: Vitamin B1 releases some anti-stress agents during the time of low immunity or to withstand stressful conditions.
  3. Role in muscle tissue: TDP or thiamin diphosphate is an active metabolite that helps in muscle cell contraction and regulates nerve signals’ conduction from one cell to the other.

Uses of Vitamin B1

Metabolic Disorders: Taking proper vitamin B-1 helps in curing metabolic disorders like Leigh’s disease and maple syrup urine disease.

Brain Disorder: It is also termed as Wernicke-Korsakoff syndrome. The proper dose of vitamin B-1 reduces the risk of brain disorder. Vitamin B-1 deficiency often occurs in alcoholic people, where 30%-80% of alcoholic people suffer from Wernicke-Korsakoff syndrome. Separately, thiamine shots are given during the alcohol withdrawal period to reduce the risk of brain disorder.

Cataract: Higher consumption of vitamin B-1 with diet reduces the risk of cataract development.

Painful Menstruation: Proper intake of vitamin B-1 reduces the pain during menstruation among girls aged between 12-21 years.

Kidney Disease: Patients with diabetes have a high risk of kidney disease due to insufficient vitamin B-1. Taking 100 mg of vitamin three times a day for three months reduces albumin in the body, and albumin presence in urine indicates kidney damage.

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