Thiamine (Vitamin B1): Foods, Benefits, Deficiencies and Side Effects

Thiamine (Vitamin B1): Foods, Benefits, Deficiencies and Side Effects

Thiamine, also known as vitamin B1, is an essential water-soluble vitamin that plays a vital role in the proper functioning of the body. It is naturally in some foods, added to foods, and sold as a supplement. It is one of the eight B vitamins and is involved in various metabolic processes. Thiamin plays a vital role in the growth and function of various cells. Only small amounts are stored in the liver, so a daily intake of thiamin-rich foods is needed.


Thiamine serves several important functions in the body:

  • Energy Metabolism: Thiamine plays a key role in the metabolism of carbohydrates. It helps convert glucose, a simple sugar, into energy that can be utilized by the body’s cells. Thiamine acts as a coenzyme, facilitating the breakdown of glucose and supporting the production of adenosine triphosphate (ATP), the primary energy currency of cells.
  • Nervous System Function: Thiamine is essential for the proper functioning of the nervous system. It is involved in the synthesis and maintenance of myelin, a fatty substance that forms a protective sheath around nerve fibers. Thiamine is also needed for the synthesis of neurotransmitters, which are chemical messengers involved in transmitting signals between nerve cells.
  • Growth and Development: Thiamine is crucial for normal growth and development, particularly during infancy, childhood, and adolescence. It supports the growth and maintenance of various tissues, including muscles, nerves, and the cardiovascular system.
  • Brain Health: Thiamine is important for maintaining optimal brain health and cognitive function. It is involved in the synthesis of acetylcholine, a neurotransmitter that plays a role in memory and learning. Thiamine deficiency can lead to neurological symptoms such as confusion, memory problems, and difficulties with coordination.
  • Antioxidant Defense: Thiamine has antioxidant properties, meaning it helps protect cells from damage caused by harmful molecules called free radicals. By neutralizing these free radicals, thiamine can help reduce oxidative stress and promote overall cellular health.

It’s important to note that the functions of thiamine are interconnected with other B vitamins and various metabolic processes in the body. Thiamine works in conjunction with other nutrients to support overall health and well-being.


Thiamine can be obtained from a variety of food sources. Here are some common foods that are good sources of thiamine:

  • Whole Grains: Whole grains such as wheat, barley, oats, and rice are excellent sources of thiamine. Opt for whole grain bread, pasta, and cereals to maximize thiamine intake.
  • Legumes: Legumes, including beans, lentils, and peas, are rich in thiamine. They are not only a good source of plant-based protein but also provide other essential nutrients.
  • Nuts and Seeds: Nuts and seeds like sunflower seeds, flaxseeds, peanuts, and pistachios contain thiamine. They can be enjoyed as a snack or incorporated into various dishes.
  • Pork: Pork, especially lean cuts like pork tenderloin, is a good source of thiamine. However, it’s important to consume pork in moderation and choose lean cuts to limit saturated fat intake.
  • Fish: Certain types of fish, such as tuna, trout, salmon, and mackerel, contain thiamine. Fish is also a good source of omega-3 fatty acids, which have numerous health benefits.
  • Organ Meats: Organ meats like liver and kidneys are high in thiamine. However, organ meats are also high in cholesterol, so they should be consumed in moderation.
  • Eggs: Eggs are a nutritious source of thiamine, along with other essential vitamins and minerals. They can be incorporated into various dishes or enjoyed as a standalone meal.
  • Yeast and Yeast Extracts: Yeast and yeast extracts, such as nutritional yeast, are good sources of thiamine. They are commonly used in cooking and can add a savory flavor to dishes.

It’s worth noting that some foods, particularly grains and cereals, may be fortified with additional thiamine to help prevent deficiency. However, it’s generally recommended to obtain nutrients from natural food sources whenever possible.


Thiamine offers several benefits for the body. Here are some of the key benefits of thiamine:

1. Energy Production

Thiamine is essential for the metabolism of carbohydrates, converting them into energy that the body can use. It helps in the breakdown of glucose and supports the production of ATP, which is the primary energy currency of cells. Adequate thiamine levels promote optimal energy production and help combat fatigue and low energy levels.

2. Nervous System Support

Thiamine plays a crucial role in maintaining the health and proper functioning of the nervous system. It is involved in the synthesis and maintenance of myelin, which is a protective sheath around nerve fibers. Thiamine also contributes to the synthesis of neurotransmitters, such as acetylcholine, which are vital for nerve signal transmission. By supporting the nervous system, thiamine promotes healthy cognitive function, memory, and overall neurological well-being.

3. Cardiovascular Health

Thiamine is important for cardiovascular health due to its involvement in energy metabolism and its influence on heart function. The heart relies on a constant supply of energy, and thiamine helps ensure proper energy production within cardiac muscle cells. Additionally, thiamine contributes to the maintenance of normal heart rhythm and supports overall cardiovascular function.

4. Brain Function and Mental Health

Thiamine is necessary for optimal brain function and mental well-being. It aids in the synthesis of neurotransmitters that are involved in mood regulation, memory, and cognitive processes. Adequate thiamine levels have been associated with improved mood, enhanced cognitive performance, and a reduced risk of certain mental health conditions.

5. Digestive Health

Thiamine plays a role in maintaining a healthy digestive system. It assists in the production of hydrochloric acid in the stomach, which is essential for proper digestion of food. Thiamine also supports the normal functioning of the gastrointestinal tract, promoting healthy digestion and absorption of nutrients.

6. Antioxidant Protection

Thiamine possesses antioxidant properties, helping to protect cells from oxidative stress caused by free radicals. By neutralizing these harmful molecules, thiamine contributes to overall cellular health and reduces the risk of oxidative damage to various tissues and organs.

It’s important to note that while thiamine offers numerous benefits, it is most effective when obtained through a balanced diet. If you have specific concerns or conditions, it’s advisable to consult with a healthcare professional to determine the appropriate thiamine intake for your individual needs.

Vitamin B1 Deficiency Diseases

Vitamin B1 deficiency, also known as thiamine deficiency, can lead to several diseases and conditions. Here are some notable ones:

  • Beriberi: Beriberi is a condition caused by severe thiamine deficiency. It is characterized by neurological and cardiovascular symptoms. There are two main types of beriberi:
    • Wet beriberi: This type primarily affects the cardiovascular system, leading to symptoms such as rapid heartbeat, enlarged heart, edema (swelling), and shortness of breath.
    • Dry beriberi: This type primarily affects the nervous system, causing symptoms such as muscle weakness, tingling or numbness in the extremities, difficulty walking, and loss of muscle coordination.
  • Wernicke-Korsakoff Syndrome: Wernicke-Korsakoff syndrome is a neurological disorder that can occur as a result of thiamine deficiency, often associated with chronic alcohol abuse. Wernicke’s encephalopathy refers to the acute phase characterized by confusion, ataxia (loss of muscle coordination), and eye movement abnormalities. If left untreated, it can progress to Korsakoff’s syndrome, which involves severe memory loss, disorientation, and confabulation (fabrication of false memories).
  • Infantile Beriberi: Infantile beriberi occurs in infants who are exclusively breastfed by thiamine-deficient mothers. It can manifest as either cardiac beriberi or cerebral beriberi. Cardiac beriberi affects the cardiovascular system, leading to symptoms such as rapid breathing, heart failure, and cyanosis (bluish discoloration of the skin). Cerebral beriberi affects the nervous system, resulting in irritability, muscle weakness, seizures, and developmental delays.
  • Alcohol-Induced Encephalopathy: Chronic alcohol abuse can lead to thiamine deficiency and subsequent alcohol-induced encephalopathy. It is characterized by a range of neurological symptoms, including confusion, memory impairment, coordination difficulties, and even coma in severe cases.
  • Other Neurological and Cognitive Impairments: Thiamine deficiency can cause a range of neurological and cognitive symptoms, such as fatigue, irritability, poor concentration, memory problems, and general cognitive decline. These symptoms can vary in severity and are often associated with inadequate thiamine intake or absorption disorders.

Thiamine deficiency-related diseases can be serious and require medical intervention. If you suspect thiamine deficiency or experience symptoms associated with these conditions, it is important to seek medical attention for proper diagnosis and treatment.

Who is at Risk of B1 Deficiency?

Several factors can increase the risk of vitamin B1 (thiamine) deficiency. These include:

  1. Chronic Alcohol Abuse: Alcohol interferes with thiamine absorption and impairs thiamine utilization in the body. Heavy alcohol consumption is a common cause of thiamine deficiency, particularly in individuals who have an alcohol use disorder.
  2. Malnutrition: Inadequate dietary intake of thiamine-rich foods can lead to deficiency. This is more common in regions where diets are heavily reliant on refined carbohydrates and lack diverse sources of thiamine, such as whole grains, legumes, and meats.
  3. Gastrointestinal Disorders: Certain gastrointestinal disorders can interfere with thiamine absorption. Conditions like Crohn’s disease, celiac disease, and chronic diarrhea can impair the body’s ability to absorb thiamine from the diet, potentially leading to deficiency.
  4. Bariatric Surgery: Individuals who have undergone certain types of weight loss surgeries, such as gastric bypass or biliopancreatic diversion, may have an increased risk of thiamine deficiency. These surgeries can reduce the absorption of thiamine and other nutrients.
  5. Older Adults: Older adults may be at a higher risk of thiamine deficiency due to age-related factors. Reduced appetite, dietary restrictions, limited food variety, and impaired absorption can contribute to inadequate thiamine intake or utilization.
  6. Pregnancy and Breastfeeding: During pregnancy and lactation, the thiamine requirements increase. Women who are pregnant or breastfeeding may be at a higher risk of thiamine deficiency if their intake does not meet the increased demands.
  7. Chronic Illnesses: Certain chronic illnesses, such as HIV/AIDS, kidney disease, and heart failure, can increase the risk of thiamine deficiency. These conditions can affect thiamine absorption, utilization, or increase the body’s thiamine requirements.
  8. Restricted Diets: Individuals following restrictive diets, such as vegan or vegetarian diets that are not well-planned, may have a higher risk of thiamine deficiency. Thiamine is more commonly found in animal-derived foods, so those on plant-based diets should ensure adequate thiamine intake from plant sources or consider supplementation.

It’s important to note that the risk factors mentioned above increase the likelihood of thiamine deficiency, but they don’t guarantee it. However, individuals with these risk factors should pay attention to their thiamine intake and consult with healthcare professionals if they have concerns about their nutritional status.

How Much Vitamin B1 Do We Need?

The recommended daily intake of vitamin B1, or thiamine, can vary depending on factors such as age, sex, and specific life stages. The dietary reference intake (DRI) values for thiamine are typically expressed in terms of milligrams (mg) per day. Here are the recommended daily intakes of thiamine for different groups:

  • Infants:
    • 0-6 months: 0.2 mg
    • 7-12 months: 0.3 mg
  • Children:
    • 1-3 years: 0.5 mg
    • 4-8 years: 0.6 mg
    • 9-13 years: 0.9 mg
  • Adolescents and Adults:
    • Males aged 14 years and older: 1.2 mg
    • Females aged 14-18 years: 1.0 mg
    • Females aged 19 years and older: 1.1 mg
    • Pregnant females: 1.4 mg
    • Breastfeeding females: 1.5 mg

It’s important to note that these values represent the recommended intakes to prevent deficiency in healthy individuals. Specific health conditions, medications, and other factors may require adjustments to the thiamine intake. Always consult with a healthcare professional for personalized dietary recommendations.


Thiamine supplementation can be beneficial in certain situations, especially when there is a diagnosed deficiency or an increased need for thiamine. Here are some cases where thiamine supplementation may be considered:

  • Thiamine Deficiency: In cases of diagnosed thiamine deficiency, supplementation is often recommended to restore thiamine levels to normal. The dosage and duration of supplementation will depend on the severity of the deficiency and the underlying cause.
  • Alcohol Withdrawal: Individuals undergoing alcohol withdrawal may benefit from thiamine supplementation. Chronic alcohol abuse can deplete thiamine stores, and sudden withdrawal can further increase the risk of deficiency and related complications, such as Wernicke-Korsakoff syndrome. Thiamine supplementation is often provided as a preventive measure in these situations.
  • Malabsorption Conditions: Certain gastrointestinal disorders, such as Crohn’s disease, celiac disease, and chronic diarrhea, can impair thiamine absorption. In such cases, supplementation may be necessary to ensure adequate thiamine levels.
  • Bariatric Surgery: Individuals who have undergone certain types of weight loss surgeries, such as gastric bypass, may have reduced thiamine absorption. Thiamine supplementation is commonly recommended after bariatric surgery to prevent thiamine deficiency.
  • Increased Thiamine Needs: There are certain conditions or circumstances that may increase thiamine requirements. This includes pregnancy, breastfeeding, intense physical activity, and certain chronic illnesses. In such cases, healthcare professionals may recommend thiamine supplementation to meet the increased needs.

It’s important to note that supplementation should be done under the guidance of a healthcare professional. They can assess your individual needs, determine appropriate dosage, and monitor your response to supplementation. Thiamine supplements are generally safe when taken as directed, but excessive intake can lead to potential side effects. It’s best to consult with a healthcare professional for personalized advice regarding thiamine supplementation.

Side Effects

Thiamine, or vitamin B1, is generally considered safe when taken within the recommended dosage guidelines. It is water-soluble, meaning that excess amounts are typically excreted through urine, reducing the risk of toxicity. However, in rare cases, high-dose supplementation may lead to certain side effects. Here are a few potential side effects of thiamine supplementation:

  • Allergic Reactions: Some individuals may experience allergic reactions to thiamine supplements. Symptoms may include rash, itching, swelling, dizziness, or difficulty breathing. If you experience any signs of an allergic reaction, discontinue use and seek medical attention immediately.
  • Gastrointestinal Disturbances: In some cases, high doses of thiamine supplements may cause gastrointestinal discomfort. This can include symptoms such as nausea, stomach pain, diarrhea, or increased frequency of bowel movements. These symptoms are usually mild and resolve on their own.
  • Injection Site Reactions: Thiamine injections may occasionally cause pain, redness, or swelling at the injection site. These reactions are typically temporary and resolve without intervention.
  • Hypersensitivity Reactions: In rare cases, thiamine supplementation, particularly in high doses, may trigger hypersensitivity reactions. This can manifest as symptoms such as itching, flushing, hives, or a rapid heartbeat. If you experience any unusual or severe symptoms, discontinue use and seek medical attention.

It’s important to note that these side effects are relatively uncommon, especially when thiamine supplements are taken at recommended dosages. If you have any concerns or are considering thiamine supplementation, it’s best to consult with a healthcare professional. They can evaluate your individual needs, provide appropriate guidance, and monitor your response to supplementation to ensure your safety and well-being.

Diagnosis and Treatment

Diagnosis and treatment of thiamine deficiency or related conditions typically involve a comprehensive assessment of symptoms, medical history, and laboratory tests. Here is an overview of the diagnosis and treatment process:


  • Medical History and Physical Examination: A healthcare professional will evaluate your medical history, including symptoms, dietary habits, alcohol consumption, and any underlying medical conditions that may increase the risk of thiamine deficiency.
  • Laboratory Tests: Blood tests can be conducted to measure thiamine levels in the blood. However, these tests may not always accurately reflect thiamine status, as thiamine is primarily present within cells rather than in the bloodstream.
  • Urinary Thiamine Levels: Measurement of thiamine and its metabolites in urine may provide more reliable information about thiamine status. A high urinary thiamine excretion and low blood thiamine level may indicate thiamine deficiency.


  • Thiamine Supplementation: If thiamine deficiency is diagnosed, the primary treatment involves thiamine supplementation. This can be in the form of oral thiamine supplements or, in severe cases or when there are absorption issues, intravenous (IV) thiamine administration.
  • Underlying Condition Management: If thiamine deficiency is caused by an underlying condition, such as alcohol abuse or gastrointestinal disorders, treating and managing the underlying condition is crucial for long-term thiamine status improvement.
  • Dietary Modifications: Encouraging a balanced diet that includes thiamine-rich foods can help prevent thiamine deficiency. Emphasize whole grains, legumes, nuts, seeds, meats, fish, eggs, and fortified cereals.
  • Lifestyle Changes: In cases where alcohol abuse contributes to thiamine deficiency, addressing alcohol dependency and adopting a healthier lifestyle are essential for long-term management.
  • Monitoring and Follow-up: Regular monitoring of thiamine levels and clinical symptoms is important to assess treatment effectiveness and ensure appropriate management.

It’s important to consult with a healthcare professional for an accurate diagnosis and personalized treatment plan. They can assess your individual situation, determine the underlying cause of thiamine deficiency, and provide appropriate guidance and monitoring throughout the treatment process.


Thiamine, also known as vitamin B1, is an essential nutrient that plays a crucial role in the body’s energy metabolism. It acts as a coenzyme, facilitating the conversion of carbohydrates into energy and supporting the proper functioning of the nervous system.

Overall, thiamine is an important nutrient that supports energy metabolism, nervous system function, and overall health. It is obtained through a balanced diet, but supplements may be necessary in specific cases. If you have concerns about thiamine or your nutritional needs, it’s best to consult with a healthcare professional for personalized advice.