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A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M.; 2013.

A.D.A.M. Medical Encyclopedia.

Thiamin

Vitamin B1; Thiamine

Last reviewed: February 18, 2013.

Thiamin is one of the B vitamins, a group of water-soluble vitamins that are part of many of the chemical reactions in the body.

Function

Thiamin (vitamin B1) helps the body's cells change carbohydrates into energy. The main role of carbohydrates is to provide energy for the body, especially the brain and nervous system

Thiamin also plays a role in muscle contraction and conduction of nerve signals. 

Food Sources

Thiamin is found in:

  • Enriched, fortified, and whole grain products such as bread, cereals, rice, pasta, and flour
  • Beef liver and pork
  • Dried milk
  • Egg
  • Legumes and peas
  • Nuts and seeds

Dairy products, fruits, and vegetables are not very high in thiamin, but when eaten in large amounts, they become a significant source.

Side Effects

A lack or deficiency of thiamin can cause weakness, fatigue, psychosis, and nerve damage.

Thiamin deficiency in the United States is most often seen in people who abuse alcohol (alcoholism). A lot of alcohol makes it hard for the body to absorb thiamin from foods. Unless those with alcoholism receive higher-than-normal amounts of thiamin to make up for the difference, the body will not get enough of the substance. This can lead to a disease called beriberi.

In severe thiamin deficiency, brain damage can occur. One type is called Korsakoff syndrome. The other is Wernicke's disease. Either or both of these conditions can occur in the same person.

There is no known poisoning linked to thiamin.

Recommendations

The Recommended Dietary Allowance (RDA) for vitamins reflect how much of each vitamin most people should get each day. The RDA for vitamins may be used as goals for each person.

How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and illnesses, are also important. Adults and pregnant or breast-feeding women need higher levels of thiamin than young children.

Dietary Reference Intakes for Thiamin:

Infants

  • 0 - 6 months: 0.2* milligrams per day (mg/day)
  • 7 - 12 months: 0.3* mg/day

*Adequate Intake (AI)

Children

  • 1 - 3 years: 0.5 mg/day
  • 4 - 8 years: 0.6 mg/day
  • 9 - 13 years: 0.9 mg/day

Adolescents and Adults

  • Males age 14 and older: 1.2 mg/day
  • Females age 14 to 18 years: 1.0 mg/day
  • Females age 19 and older: 1.1 mg/day

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods.

References

  1. Escott-Stump S, ed. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.
  2. Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements. 3rd ed. Chicago, Il: American Dietetic Association;2007.
  3. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, PantothenicAcid, Biotin, and Choline. National Academy Press, Washington, DC, 1998. [PubMed: 23193625]
  4. Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Ausiello D, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 225.

Review Date: 2/18/2013.

Reviewed by: Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.

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Copyright © 2013, A.D.A.M., Inc.

What works?

  • Insufficient evidence of the efficacy of thiamine for people with Alzheimer's diseaseInsufficient evidence of the efficacy of thiamine for people with Alzheimer's disease
    Preclinical and laboratory studies show an effect of thiamine on the release and breakdown of acetylcholine. Some intellectual functions, including attention and memory, are influenced by neurons which release acetylcholine. Cholinergic function is impaired in Alzheimer's disease. It has therefore been hypothesized that thiamine may be beneficial in Alzheimer's disease. Biochemical abnormalities in thiamine‐dependent enzymes have been found in the brains of patients with Alzheimer's disease. The three included randomized controlled trials totaled less than 50 participants and insufficient detail in the results did not allow combination of the data. Thus the review found no evidence of the efficacy of thiamine for people with Alzheimer's disease.
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Figures

  • Vitamin B1 benefit.
    Vitamin B1 source.

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