Where do you get thiamin from?

December 12, 2025 •

4 min read

According to the National Institutes of Health, about half of the thiamin in the U.S. diet comes from foods with naturally occurring thiamin, while the other half comes from fortified foods where the vitamin has been added back. A continuous daily intake of thiamin is essential because the body stores only small amounts.

Quick Summary

Thiamin, or vitamin B1, is an essential nutrient obtained from various natural food sources like whole grains, meats, and legumes, and also from fortified products such as cereals and bread. It is crucial for energy metabolism and nervous system health, making consistent dietary intake vital.

Key Points

Natural Sources: Get thiamin naturally from whole grains, pork, fish, nuts, seeds, and legumes.
Fortified Foods: Many breads, cereals, and infant formulas are fortified with thiamin to prevent deficiency.
Water-Soluble: Because thiamin is water-soluble, your body cannot store large amounts, so regular intake is necessary.
Cooking Matters: High-heat cooking and boiling can destroy thiamin; opt for cooking methods that use less water and heat.
Supplementation: Supplements may be beneficial for individuals with deficiency risks, such as those with excessive alcohol use, certain medical conditions, or low dietary intake.
No Toxicity: It is not possible to ingest a toxic amount of thiamin from food, as the body excretes excess through urine.
Absorption: Thiamin is absorbed in the small intestine through both active and passive transport mechanisms.

Thiamin, also known as vitamin B1, is a vital water-soluble vitamin that plays a crucial role in converting food into energy and supporting the function of the brain and nervous system. Since the human body does not produce thiamin on its own and stores it in limited quantities, it must be obtained through a consistent daily diet. A varied diet consisting of both naturally rich sources and fortified foods is the most effective way to ensure an adequate intake of this essential nutrient.

Excellent Natural Food Sources of Thiamin

Nature provides a wide range of foods that are naturally rich in thiamin. Integrating these into your daily meals can help you meet your nutritional needs without relying solely on fortified products. Some of the most potent natural sources include:

Meats: Pork is one of the richest sources of thiamin. Beef and poultry also contain notable amounts.
Fish and Seafood: Several types of fish are good sources, including salmon, trout, tuna, and mussels.
Legumes: A variety of beans and lentils, such as black beans, navy beans, green peas, and edamame, are excellent for boosting your thiamin intake.
Nuts and Seeds: Nuts and seeds, particularly sunflower seeds and macadamia nuts, provide a healthy dose of vitamin B1.
Whole Grains and Wheat Germ: The germ of the wheat kernel is a particularly concentrated source of thiamin. Whole-grain products like brown rice, oats, and quinoa retain their natural thiamin content, unlike their refined counterparts.

The Role of Fortified and Enriched Foods

Food fortification has been a successful public health strategy for decades, helping to prevent widespread thiamin deficiency. During the refining process, many grains lose their natural B vitamins, so manufacturers enrich them by adding these nutrients back.

Cereals and Grains: Many breakfast cereals, breads, pastas, and white rice are fortified with thiamin, making them a common source in many diets.
Infant Formula: To ensure proper growth and development, infant formulas are also enriched with thiamin.

Thiamin vs. Fortified Thiamin

To understand your intake, it's helpful to distinguish between natural and fortified sources.


Feature	Natural Thiamin Sources	Fortified Thiamin Sources
Processing	Found in unprocessed or minimally processed foods.	Added back to refined grains after processing removes the natural vitamin.
Nutrient Profile	Provides thiamin along with a complex profile of other vitamins, minerals, and fiber.	Primarily provides thiamin and other added nutrients, but the original nutrient content of the refined grain is lost.
Concentration	Thiamin content can vary depending on the food and its preparation.	Content is standardized and often provides a high percentage of the Daily Value per serving, as seen in many breakfast cereals.
Cooking Effects	High heat and long cooking times can reduce the thiamin content, and it can leach into water.	Stability can be affected by high heat, but fortification ensures a consistent intake level.

Important Considerations for Thiamin Intake

While getting thiamin from food is straightforward for most people, certain factors can influence your intake and absorption. For example, excessive alcohol consumption can interfere with absorption and metabolism, increasing the risk of a deficiency. Likewise, older adults and those with certain medical conditions like diabetes may have lower thiamin levels. When dietary intake is not sufficient, or for individuals with specific health needs, supplementation may be recommended by a healthcare provider. Supplemental forms, such as benfotiamine, can offer higher bioavailability than standard oral thiamin.

Conclusion: A Balanced Approach for Optimal Thiamin

Achieving an adequate thiamin intake is a simple and essential aspect of a healthy diet. By incorporating a variety of whole grains, lean meats, fish, legumes, nuts, and fortified cereals into your meals, you can easily obtain the vitamin B1 needed for crucial bodily functions. Remember that cooking methods matter—opt for steaming or microwaving vegetables rather than boiling to preserve thiamin content. If you have dietary restrictions or underlying health conditions, consult a healthcare provider to determine if supplementation is right for you. A balanced and varied approach to eating is your best defense against thiamin deficiency and the key to maintaining your overall health.

What is the Recommended Dietary Allowance (RDA) for thiamin?

RDA: The RDA for adult men is 1.2 mg daily and for adult women is 1.1 mg daily. Pregnant or breastfeeding women require a slightly higher intake of 1.4 mg daily.

Are there any foods that destroy thiamin?

Thiaminases: Certain foods like raw fish, raw shellfish, tea, and coffee contain enzymes called thiaminases that can destroy thiamin. However, cooking these foods deactivates the enzymes, and consuming them is unlikely to cause a deficiency.

Can a thiamin deficiency cause serious health problems?

Severe Complications: A severe thiamin deficiency, though rare in developed countries, can lead to serious conditions like beriberi, which affects the nervous and cardiovascular systems, and Wernicke-Korsakoff syndrome, which causes brain abnormalities and memory problems.

How is thiamin absorbed by the body?

Absorption: At low concentrations, the small intestine actively transports thiamin, while at higher concentrations, it uses a passive diffusion process. Excess thiamin is excreted in the urine because it is water-soluble.

What are the symptoms of a mild thiamin deficiency?

Early Signs: Early, vague symptoms of a mild thiamin deficiency can include fatigue, irritability, poor memory, loss of appetite, and weight loss.

Is it possible to get too much thiamin from my diet?

No Known Toxicity: It is unlikely to reach a toxic level of thiamin from food alone. Your body flushes out excess amounts through urine, and no tolerable upper intake level (UL) has been established for thiamin.

What cooking methods preserve thiamin best?

Preserving Thiamin: Since thiamin is water-soluble and sensitive to high heat, cooking methods like steaming or microwaving are better than boiling, which can cause the vitamin to leach into the water.

Frequently Asked Questions

Thiamin is found in a wide variety of foods, with the best natural sources including pork, fish (like trout and tuna), legumes (such as beans and lentils), and whole grains. Many processed cereals and breads are also fortified with this vitamin.

Yes, there is a significant difference. While brown rice naturally contains thiamin, the refining process strips it from white rice. Although most white rice is enriched, it still contains only about one-tenth of the thiamin found in brown rice.

Thiamin is sensitive to heat and water. Cooking at high temperatures for long periods or boiling foods can cause a significant loss of the vitamin, as it leaches into the cooking water. Steaming or microwaving can help preserve thiamin.

Certain individuals are at higher risk, including people with chronic alcohol use disorder (alcoholism), older adults, those who have undergone bariatric surgery, and individuals with specific gastrointestinal or liver diseases.

For most healthy individuals who consume a balanced diet, thiamin supplements are not necessary as the body's daily needs can be met through food. Supplements are generally recommended for those with a confirmed deficiency or specific risk factors under medical supervision.

Benfotiamine is a synthetic, fat-soluble derivative of thiamin found in some supplements. It is more bioavailable than the standard water-soluble form, meaning the body absorbs it more easily. It is often used to prevent or treat thiamin deficiency.

Yes. Aside from alcohol, certain substances found in raw fish, shellfish, tea, and coffee can interfere with thiamin absorption, though the effect is minimal and a varied diet typically prevents issues. Some diuretics and chemotherapy drugs can also reduce thiamin concentrations.