Thiamin, also known as vitamin B1, is a water-soluble vitamin essential for various cellular functions, growth, and energy metabolism. While naturally present in certain foods, it’s also added to others and available as a supplement. Because the body stores only limited amounts of thiamin in the liver, incorporating thiamin-rich foods into your daily diet is crucial.
Paper bags filled with dry beans, peas, lentils, and rice
The connection between diet and thiamin deficiency wasn’t established until the late 19th century, despite its symptoms being documented in ancient Chinese medicine. A Japanese physician observed high illness and death rates among sailors consuming a solely rice-based diet. These rates decreased significantly when their diet was diversified with whole grains, meats, beans, and vegetables. Simultaneously, Dutch scientists discovered that chickens fed polished white rice developed leg paralysis, while those fed unpolished brown rice did not, leading to the discovery of thiamin in the outer layers of rice.
Recommended Daily Intake of Vitamin B1
- RDA (Recommended Dietary Allowance): The RDA for thiamin is 1.2 mg daily for men aged 19 and older and 1.1 mg daily for women in the same age range. This increases to 1.4 mg daily during pregnancy and lactation.
- UL (Tolerable Upper Intake Level): There is no established UL for thiamin, as studies have not reported adverse effects from high intakes.
Health Benefits of Vitamin B1
Thiamin plays a vital role in breaking down nutrients for energy and maintaining basic cell functions. A deficiency can disrupt energy supply to the brain and heart, leading to various health problems.
- Congestive Heart Failure: Thiamin deficiency can impair heart motor functions, potentially leading to congestive heart failure, a condition where the heart struggles to pump blood effectively. Studies show that thiamin deficiency affects 21% to 98% of people with congestive heart failure. Thiamin supplementation has been shown to significantly improve heart function in heart failure patients, especially among the elderly, those with poor nutrition, or those on high doses of diuretics.
- Cognitive Function: Research indicates that thiamin deficiency contributes to neurological issues like cognitive decline. Wernicke-Korsakoff syndrome, a severe form of thiamin deficiency, can cause mental status changes similar to Alzheimer’s disease. Studies suggest thiamin deficiency could lead to oxidative stress, nerve cell death, memory loss, plaque formation, and reduced glucose metabolism, all risk factors for Alzheimer’s. While human research is limited, these findings suggest a potential link between thiamin and cognitive health.
What Food Has Vitamin B1 In It? Top Sources
Thiamin can be found naturally in many foods. Here are some excellent sources of dietary vitamin B1:
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Fortified Breakfast Cereals: Many breakfast cereals are fortified with thiamin, making them a convenient source.
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Pork: Pork is a rich source of thiamin.
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Fish: Various types of fish contain thiamin.
Image alt text: A raw salmon fillet showcasing a natural source of vitamin B1 rich food.
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Beans and Lentils: Legumes like beans and lentils are excellent plant-based sources of thiamin.
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Green Peas: Green peas contribute to your daily thiamin intake.
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Enriched Grains: Enriched cereals, breads, noodles, and rice often have thiamin added.
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Sunflower Seeds: These seeds are a good source of thiamin.
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Yogurt: Certain types of yogurt provide thiamin.
Signs of Vitamin B1 Deficiency and Toxicity
Deficiency
Thiamin deficiency is rare in the U.S. because most people get enough from their diet. However, it can occur due to low intake, decreased gut absorption, or increased losses in urine (often associated with alcohol abuse or diuretic medications).
A severe deficiency can lead to beriberi, characterized by muscle loss and peripheral neuropathy (diminished feeling in hands and feet). Beriberi impairs reflexes and motor function, potentially leading to fluid build-up in the heart and lower limbs, which can be fatal. Wernicke-Korsakoff syndrome, often seen in alcohol abuse cases, is another severe consequence, causing confusion, loss of muscle coordination, and peripheral neuropathy. These deficiencies are also observed in those with gastrointestinal conditions like celiac disease or after bariatric surgery, and in individuals with HIV/AIDS. Treatment involves high-dose supplements or intravenous injections, alongside a balanced diet.
Symptoms of mild to moderate thiamin deficiency include:
- Weight loss
- Confusion, memory loss
- Muscle weakness
- Peripheral neuropathy
- Lowered immunity
Toxicity
It is unlikely to reach toxic levels of thiamin from food sources alone. High intakes prompt the body to absorb less and excrete excess amounts through urine. There is no established toxic level for thiamin.
Interesting Facts About Thiamin
- Thiamin is destroyed by high-heat cooking or long cooking times. It also leaches into water, so discarding cooking or soaking water results in thiamin loss.
- Food processing, such as refining white bread and rice, can remove thiamin. This is why thiamin is added back to many processed breads, cereals, and grains.
- Certain foods and beverages, including tea, shellfish, clams, and raw fish, contain thiaminases, enzymes that deactivate thiamin. However, developing a deficiency from these foods is rare.
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References
Last reviewed March 2023
