Thiamin, also spelled thiamine and previously known as vitamin B1, is a micronutrient essential for the metabolism of carbohydrates that converts sugar into energy for the body and for normal nerve and heart function. Thiamin deficiency causes a condition known as beriberi or beri-beri. The initial symptoms are very vague. The first indication of thiamin deficiency may be simple fatigue. As the condition becomes more advanced, there is a wide range of symptoms, affecting many organ systems. These include but are not limited to chest pains, memory loss, muscle cramps, and weakness. In more advanced cases, muscle atrophy and heart failure may be present.


Thiamin has several important functions. It works with other B-group vitamins to help release energy from the food we eat and it keeps nerves and muscle tissue healthy. In the form of thiamin pyrophosphate (TPP), it plays an essential role as a cofactor in key reactions, such as breaking down food and converting carbohydrate into energy for the body (carbohydrate metabolism). Like other B-complex vitamins, thiamin is also considered an anti-stress vitamin because it is believed to enhance the activity of the immune system and increase the body's ability to resist stressful conditions.

Thiamin also plays a therapeutic role in the prevention or treatment of the following diseases:


Thiamin is a micronutrient, meaning a nutrient needed in very small amounts, found in a variety of animal and plant foods. It is a water-soluble vitamin that it is eliminated in urine when not needed by the body. Food must therefore supply it continuously. It belongs to a group of other water-soluble vitamins that are often present together and called B-complex. The other members of the vitamin B complex are riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folic acid, inositol, and vitamin B12. Important sources of thiamin are vegetables, whole-grain products, and nuts. The best sources are yeasts and liver and pork meat. Some specific good food sources of thiamin include (per 1 cup serving or as indicated):



Recommended dietary

Children 0-6 mos.


Children 7-12 mos.


Children 1-3 yrs.


Children 4-8 yrs.


Children 9-13 yrs.


Boys 14-18 yrs.


Girls 14-18 yrs.


Men 19≥ yrs.


Women 19≥ yrs.


Pregnant women


Breastfeeding women



Thiamin (mg)

Trail mix, 1 cup


Instant oatmeal, 1 packet


Pork chops, bone in, 3 oz.


Spaghetti or macaroni noodles, 1 cup


White rice, enriched, cooked, 1 cup


Pita bread, white, enriched, 6 1/2"


Pinto beans, 1 cup


Pretzels, 10


Green peas, 1/2 cup


Black beans, 1/2 cup


Pineapple, 1 cup


mg = milligram

SOURCE: U.S. Department of Agriculture, National Agricultural Library, Food and Nutrition Information Center and USDA Agricultural Research Service.

The recommended dietary allowances (RDA) for thiamin are:

Thiamin in nutritional supplements can be found in multivitamins, B-complex vitamins, or can be sold individually. It may be labeled as thiamine hydrochloride or thiamine mononitrate and is available in a variety of forms including tablets, softgels, and lozenges, including chewable and liquid drops. Two fat-soluble forms of thiamin are also used. They are thiamin propyl disulfide and thiamin tetrahydrofurfuryl disulphide, and are sometimes used in treatment of thiamin deficiency because they follow a different route of absorption into the body than water-soluble thiamin.


Foods highest in thiamin.

Foods highest in thiamin.
Alzheimer's disease—
A progressive, incurable condition that destroys brain cells, gradually causing loss of intellectual abilities, such as memory, and extreme changes in personality and behavior.
Amino acid—
Organic (carbon-containing) molecules that serve as the building blocks of proteins.
Drug that kills bacteria and other germs.
Drugs used primarily to treat depression.
B-group vitamins—
Group of eight water-soluble vitamins that are often present as a single vitamin complex in many natural sources, such as rice, liver, and yeast.
Any of a group of organic compounds that includes sugars, starches, celluloses, and gums and serves as a major energy source for the body.
Treatment of cancer with drugs.
A compound that is essential for the activity of an enzyme.
Crohn's disease—
Inflammatory disease that usually occurs in the last section of the small intestine (ileum), causing swelling in the intestines. It can also occur in the large intestine.
A substance that increases the flow of urine from the body.
A biological catalyst, meaning a substance that increases the speed of a chemical reaction without being changed in the overall process. Enzymes are proteins and are vitally important to the regulation of the chemistry of cells and organisms.
A disorder of the brain that results in recurrent, unprovoked seizures.
Fat-soluble vitamins—
Vitamins, such as A, D, E, and
K, that are found in fat or oil-containing foods, and which are stored in the liver, so that daily intake is not really essential.
Widespread musculoskeletal pain and fatigue disorder for which the cause is still unknown.
The sum of the processes (reactions) by which a substance is assimilated and incorporated into the body or detoxified and excreted from the body.
Nutrients needed by the body in small amounts. They include vitamins and minerals.
Multiple sclerosis—
A chronic degenerative disease of the central nervous system in which gradual destruction of myelin occurs in patches throughout the brain or spinal cord, interfering with the nerve pathways and causing muscular weakness, loss of coordination, and speech and visual disturbances.
Biological molecules that consist of strings of smaller units called amino acids, the “building blocks” of proteins. In proteins, amino acids are linked together in sequence as polypeptide chains that fold into compact shapes of various sizes. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs, and each protein has unique functions.
Recommended dietary allowance (RDA)—
The levels of intake of essential nutrients judged on the basis of scientific knowledge to be adequate to meet the nutrient needs of healthy people by the Food and Nutrition Board of the National Research Council/National Academy of Sciences. The RDA is updated periodically to reflect new knowledge. It is popularly called the recommended daily allowance.
A group of organic micronutrients, present in minute quantities in natural foodstuffs, that are essential to normal metabolism.x
Water-soluble vitamins—
Vitamins that are soluble in water, including the B-complex group and vitamin C. Whatever water-soluble vitamins are not used by the body are eliminated in urine, which means that a continuous supply is needed in food.


Thiamin is known to interact with the following medications and should not be taken at the same time:

Thiamin can also interact with food substances. Foods and beverages that may inactivate thiamin include those containing sulfites and tea, coffee, and decaffeinated coffee. Consumption of betel nuts may also reduce thiamin activity due to chemical inactivation, and may lead to symptoms of thiamin deficiency. Tobacco use also decreases thiamin absorption and may lead to decreased levels in the body.


All forms of thiamin deficiency are treated with supplements. If severe deficiency results in a medical emergency, it is treated with high doses of thiamin for several days. When alcoholics must be fed intravenously, they are often given supplements as a preventive measure. Doses for conditions, such as severe beriberi or alcoholism, are administered by a healthcare practitioner in an appropriate clinical setting. The symptoms of beriberi may recur years after apparent recovery.


Brain abnormalities due to thiamin deficiency are complications that occur mainly in alcoholics. They may develop when a chronic thiamin deficiency is suddenly worsened by a rapid decrease in the thiamin levels by an alcoholic binge or by a sudden increase in thiamin requirements when a malnourished alcoholic is fed intravenously. Brain abnormalities may develop in two stages: an early stage (Korsakoff's syndrome) and a later stage (Wernicke's encephalopathy). Together, they are called the Wernicke-Korsakoff syndrome. Korsakoff's syndrome causes memory loss, and Wernicke's encephalopathy causes mental confusion, difficulty walking, and eye problems. If Wernicke's encephalopathy is not treated, symptoms may lead to coma and even death. As for excessive thiamin intake complications, rare hypersensitivity/allergic reactions have occurred with supplementation.

Parental concerns

Parents should refrigerate fresh produce and keep milk and grains away from strong light because vitamins are easily destroyed and washed out during food preparation and storage. Vitamin supplements should also be stored at room temperature in a dry place.

Taking thiamin for a long period of time can result in an imbalance of other B-complex vitamins. This is why it is generally recommended to take a B-complex vitamin with thiamin. Because of the potential for side effects and interactions with medications, thiamin supplements should also be taken only under the supervision of a knowledgeable healthcare provider.



Berkson, Burt, and Arthur J. Berkson. Basic Health Publications User's Guide to the B-Complex Vitamins. Laguna Beach, CA: Basic Health, 2012.

Carpenter, Kenneth J. Beriberi, White Rice, and Vitamin B: A Disease, a Cause, and a Cure. Berkeley: University of California Press, 2000.

Challem, Jack, and Liz Brown. Basic Health Publications User's Guide to Vitamins & Minerals. North Bergen, NJ: Basic Health, 2002.

Duyff, Roberta Larson. Academy of Nutrition and Dietetics Complete Food and Nutrition Guide. 5th ed. Boston: Houghton Mifflin Harcourt, 2017.

Garrison, Robert, Jr., and Elizabeth Somer. The Nutrition Desk Reference. 3rd ed. New York: McGraw-Hill, 1998.

Griffith, H. Winter. Minerals, Supplements & Vitamins: The Essential Guide. Tucson, AZ: Fisher Books, 2000.

Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academies Press, 1998.

Lieberman, Shari, and Nancy Bruning. The Real Vitamin and Mineral Book: The Definitive Guide to Designing Your Personal Supplement Program. 4th ed. New York: Avery, 2007.


Higdon, Jane, Victoria J. Drake, and Barbara Delage. “Thiamin.” Linus Pauling Institute, Oregon State University. (accessed April 19, 2018).

Mayo Clinic staff. “Thiamin.” . (accessed April 19, 2018).

MedlinePlus. “Thiamin.” U.S. National Library of Medicine, National Institutes of Health. (accessed April 19, 2018).

Stroh, Christine, Frank Meyer, and Thomas Manger. “Beriberi, A Severe Complication after Metabolic Surgery: Review of the Literature.” Obesity Facts 7, no. 4 (2014): 246–52.

U.S. Department of Agriculture, National Agricultural Library. “DRI Tables and Application Reports.” Food and Nutrition Information Center. (accessed March 15, 2018).


Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600,, .

Food and Nutrition Information Center, National Agricultural Library, 10301 Baltimore Ave., Rm. 105, Beltsville, MD, 20705, (301) 504-5414, Fax: (301) 504-6409,, .

Institute of Medicine, National Academy of Sciences, 500 Fifth St. NW, Washington, DC, 20001, (202) 334-2352,, .

U.S. Food and Drug Administration, 10903 New Hampshire Ave., Silver Spring, MD, 20993-0002, (888) INFO-FDA (463-6332), .

Monique Laberge, PhD

  This information is not a tool for self-diagnosis or a substitute for professional care.