What Foods Are High in Thiamine B1?

October 31, 2025 •

4 min read

Thiamine, also known as vitamin B1, is a water-soluble vitamin essential for converting food into energy, supporting nerve function, and maintaining a healthy heart. Knowing what foods are high in thiamine B1 is key to preventing deficiency and supporting overall wellness. Since the body only stores small amounts and cannot produce it, a consistent dietary intake is necessary.

Quick Summary

Thiamine is vital for energy metabolism and nerve function, requiring regular intake. Key sources include pork, fortified grains, nuts, seeds, and legumes to prevent deficiency and support cellular health.

Key Points

Essential for Energy: Thiamine (Vitamin B1) helps convert food, especially carbohydrates, into energy for the body's cells.
Rich Animal Sources: Excellent animal-based sources include pork, fish like salmon and trout, and mussels.
Potent Plant Foods: Legumes, nuts, and seeds, particularly sunflower seeds, are robust plant-based options.
Fortification is Key: Refined grains often have thiamine added back (fortified), which is a significant source in many modern diets.
Water-Soluble and Heat-Sensitive: Thiamine is lost in cooking water and is unstable with prolonged high heat, so cooking methods matter.
High-Risk Groups: Individuals with alcoholism, post-bariatric surgery, and those on certain medications are at higher risk for deficiency.

What is Thiamine (Vitamin B1)?

Thiamine, or vitamin B1, is a crucial nutrient that enables the body to use carbohydrates as energy. It plays a critical role in cellular growth, development, and function across the body, including the brain, nerves, and heart. Since it's a water-soluble vitamin, the body does not store it in large quantities and flushes out excess amounts through urine, meaning a steady dietary supply is vital for health. Thiamine was the first B vitamin to be discovered, hence its name, B1.

Top Foods High in Thiamine

To ensure adequate intake, a balanced diet rich in thiamine is the best approach. Good sources are widely available from both animal and plant-based foods, as well as fortified products.

Animal-Based Sources

Pork: One of the best natural sources of thiamine, a 100-gram serving of broiled pork chop provides a significant portion of the recommended daily intake.
Fish: Several types of fish are excellent sources, including salmon, trout, and bluefin tuna.
Mussels: Seafood like mussels also provides a good dose of thiamine.
Organ Meats: Liver is particularly rich in thiamine.
Eggs: A good, reliable source of vitamin B1.

Plant-Based Sources

Legumes: Lentils, black beans, green peas, and soybeans are all excellent plant-based sources of thiamine.
Nuts and Seeds: Sunflower seeds are exceptionally high in thiamine, and nuts like macadamia nuts and pecans are also good contributors.
Whole Grains: Brown rice, oatmeal, and whole-wheat bread naturally contain thiamine in the bran and germ.
Nutritional Yeast: Often used as a cheese-like flavoring in vegan cooking, just a few spoonfuls can provide more than 100% of the daily value.
Vegetables: While not as concentrated as other sources, vegetables like acorn squash and oranges contain thiamine and contribute to overall intake.

Fortified and Enriched Foods

Modern diets often rely heavily on fortified and enriched foods to meet thiamine needs. Food manufacturers add thiamine back to refined grain products like white rice, white flour, and cereals to prevent deficiency.


Comparison of Thiamine Content: Enriched vs. Unenriched Grains	Food Item	Thiamine Content	Notes
Fortified Breakfast Cereal	Very high (often 100% DV per serving)	Thiamine is added during manufacturing.
Enriched White Rice (cooked, 1/2 cup)	0.1 mg	Thiamine is added back after processing.
Brown Rice (cooked, 1/2 cup)	0.2 mg	Naturally occurring, more than enriched white rice.
Whole-Wheat Bread (1 slice)	0.1 mg	Naturally occurring thiamine.
Enriched Pasta (cooked, 1 cup)	0.5 mg	Thiamine is added back to refined flour products.

The Function of Thiamine in the Body

Thiamine's primary function is as a coenzyme in the metabolism of carbohydrates and branched-chain amino acids. This is a crucial process for producing adenosine triphosphate (ATP), the body's main energy molecule. A constant supply of thiamine is especially important for organs with high energy demands, such as the brain and heart. Thiamine also plays a role in nerve function, protecting nerves from oxidative damage, and maintaining the muscle tone of the digestive tract.

Factors Affecting Thiamine Levels

Several factors can influence the body's thiamine levels, from dietary choices to certain medical conditions.

Dietary Considerations

Cooking Methods: Since thiamine is water-soluble and sensitive to heat, significant amounts can be lost during cooking, especially boiling. Steaming or quickly stir-frying can help preserve more of the vitamin.
Food Processing: The refining of grains, like creating white rice from brown rice, removes most of the naturally occurring thiamine. This is why fortification is so important in many countries.
Thiaminases: Some foods, including raw fish and shellfish, contain enzymes called thiaminases that destroy thiamine. However, this is generally only a concern with extremely high consumption of these raw products.
Excessive Caffeine/Alcohol: High consumption of coffee or tea, and particularly alcohol abuse, can interfere with thiamine absorption and increase risk of deficiency.

Medical and Lifestyle Factors

Alcoholism: Chronic alcohol use significantly impairs thiamine absorption and utilization, making it a leading cause of deficiency in developed countries.
Bariatric Surgery: Post-surgery malabsorption can lead to severe thiamine deficiency if not properly managed with supplementation.
Diabetes: Studies have found that individuals with type 1 and type 2 diabetes often have lower thiamine levels.
Diuretic Use: Certain diuretics can increase the excretion of thiamine through the kidneys.

Conclusion

Thiamine is a foundational nutrient that supports our body's fundamental energy and nerve functions. By understanding which foods are high in thiamine B1, from animal proteins like pork and salmon to plant-based options such as legumes and seeds, you can build a more resilient and energy-rich diet. Embracing whole grains and fortified products is also an effective strategy. While thiamine deficiency is uncommon in many parts of the world, making conscious food choices and being aware of factors that can impact thiamine absorption is key to ensuring you meet your body's daily needs and reap the full benefits of this essential vitamin. For more information on dietary reference intakes, consult reliable sources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

Thiamine deficiency can lead to a condition called beriberi, which affects the heart and nervous system. Severe deficiency can cause Wernicke-Korsakoff syndrome, which impacts the brain and is often seen in individuals with alcohol abuse.

No, it is highly unlikely to consume toxic amounts of thiamine from food alone. As a water-soluble vitamin, the body simply excretes any excess through urine, and there is no established upper intake limit for thiamine from diet.

Naturally, brown rice contains more thiamine than white rice, as the refining process removes the vitamin. However, many white rice products are enriched with thiamine to compensate for this loss.

The Recommended Dietary Allowance (RDA) is 1.2 mg per day for adult males and 1.1 mg per day for adult females. The amount increases to 1.4 mg daily for pregnant and breastfeeding women.

Yes, thiamine is sensitive to heat and is water-soluble, meaning it can be destroyed by high temperatures or leached into cooking water. Steaming or roasting with minimal water can help preserve more of the vitamin.

All B vitamins are water-soluble and help with metabolism, but each has a specific role. Thiamine (B1) is crucial for converting carbohydrates into energy, while other B vitamins, like B12, focus on red blood cell production and nerve function.

Yes, nutritional yeast is an excellent source of thiamine. A five-gram serving can provide a significant portion of the daily requirement, making it a popular choice, especially in vegan diets.