Thiamin

Definition

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

Alternative Names

Vitamin B1; Thiamine

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.

Thiamin is essential for the metabolism of pyruvate.

Food Sources

Thiamin is found in:

• Enriched, fortified, and whole grain products such as bread, cereals, rice, pasta, and flour
• Wheat germ
• Beef steak and pork
• Trout and bluefin tuna
• Egg
• Legumes and peas
• Nuts and seeds

Dairy products, fruits, and vegetables are not very high in thiamin in small amounts. But when you eat large amounts of these, they become a significant source of thiamin.

Side Effects

A lack 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 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 sex. Other factors, such as pregnancy and illnesses, are also important. Adults and pregnant or breastfeeding women need higher levels of thiamin than young children.

Dietary Reference Intakes for thiamin:

Infants

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

*Adequate Intake (AI)

Children

• 1 to 3 years: 0.5 mg/day
• 4 to 8 years: 0.6 mg/day
• 9 to 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 (1.4 mg needed during pregnancy and lactation)

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

Images

References

Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.

Sachdev HPS, Shah D. Vitamin B deficiencies and excess. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 62.

Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 26.

Smith B, Thompson J. Nutrition and growth. In: The Johns Hopkins Hospital, Hughes HK, Kahl LK, eds. The Harriet Lane Handbook. 21st ed. Philadelphia, PA: Elsevier; 2018:chap 21.