Thiamine

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Thiamine

OVERVIEW

Thiamine (THYE-uh-min) is the water-soluble vitamin, vitamin B₁. It is also known as 3-(4-Amino-2-methylpyrimidyl-5-methyl)-4-methyl-5,β-hydroxyethylthiazolium. It is usually made available as one of its salts, especially thiamine hydrochloride or thiamine mononitrate. Both salts are white crystalline solids with a bitter taste that are destroyed by alkaline solutions. An alkaline solution is one that contains a strong base.

Thiamine was discovered by Japanese scientist Suzuki Umetaro (1874–1943) in the early twentieth century. Umetaro was investigating a disease known as beriberi that had plagued humans for thousands of years. He found that the disease could be cured by feeding patients a diet that contained rice bran. He was also able to isolate a specific compound in rice bran that produced that effect, a compound he named aberic acid. Aberic acid later became known as thiamine.

KEY FACTS

OTHER NAMES:

Vitamin B₁

FORMULA:

C₁₂H₁₇ClN₄OS

ELEMENTS:

Carbon, hydrogen chlorine, nitrogen, oxygen, sulfur

COMPOUND TYPE:

Organic

STATE:

Solid

MOLECULAR WEIGHT:

300.82 g/mol

MELTING POINT:

Not applicable

BOILING POINT:

Not applicable

SOLUBILITY:

Soluble in water; partially soluble in ethyl alcohol

The first written reports of beriberi date back 4,000 years. Chinese scholars described a disorder characterized by nausea, vomiting, constipation, abdominal pain, weakness, wasting, paralysis, irritability, paranoia, depression, and other mental symptoms. In the 1800s, most scientists were convinced that bacteria were responsible for the disease. Over time, it became apparent that this theory was incorrect and that dietary factors were responsible for beriberi. In the late nineteenth century, for example, Japanese naval scientist Kanehiro Takaki (1849–1920) noticed that sailors on long voyages developed beriberi if their diets consisted mainly of rice with hulls removed. He also observed that the sailors remained healthy if they included fish, vegetables, wheat, and milk along with rice in their diets.

In 1896, Dutch physician Christiaan Eijkman (1858–1930) found that animals developed beriberi only if they ate polished rice—rice from which hulls had been removed. He learned that the animals recovered if they ate rice with hulls still on it. His colleague Gerrit Grijins (1865–1944) believed that the rice hulls contained some substance that prevented beriberi. By 1910, Umetaro had found that substance, aberic acid.

Interesting Facts

The word beriberi comes from the Sinhalese expression "I can't, I can't." Sinhalese is the language spoken by natives of Sri Lanka.
As of 2006, Beriberi is rare in developed countries because of the ready availability of foods and vitamin supplements that contain vitamin B₁. The disease became common in Cuba between 1989 and 1995, however. A trade embargo imposed by the United States reduced the availability of foods and vitamins for the Cuban people.

HOW IT IS MADE

Humans are unable to synthesize thiamine, so they must obtain the vitamin from other sources in which it occurs naturally. The best sources of thiamine are brewer's yeast, whole grains, wheat germ, lean meats, organ meats (such as liver and kidney), fish, dried beans, soybeans, peas, nuts, green leafy vegetables, avocados, raisins, plums, and kelp. Thiamine is also made synthetically by a process that was first developed in the 1930s by American chemist Robert R. Williams (1886–1965). Williams began his studies of antiberiberi compounds in 1911 and worked for twenty-five years before discovering the correct chemical formula for the compound. Once he had that information, he was able to invent a system for producing the vitamin artificially. Today, virtually all of the vitamin B₁ sold commercially is prepared artificially.

COMMON USES AND POTENTIAL HAZARDS

Thiamine is a coenzyme needed for a number of essential biochemical reactions in the body. A coenzyme is a chemical compound that works along with an enzyme to increase the rate at which chemical reactions take place. Without enzymes and coenzymes in the body, many chemical reactions would take place so slowly that normal bodily functions could not continue. Thiamine is involved in chemical reactions by which blood is produced and circulated through the body, carbohydrates are metabolized, digestive enzymes are produced, and the nervous system is maintained.

Words to Know

COENZYME: A chemical compound that works along with an enzyme to increase the rate at which chemical reactions take place.
SALT: An ionic compound where the anion is derived from an acid.

Because it is soluble in water, thiamine is not stored in the body. A person must include the compound in his or her daily diet on a regular basis. Most people ingest adequate amounts of vitamin B₁ in their ordinary diets, and beriberi is very rare in developed countries of the world. It may occur, however, in alcoholics, pregnant women, and people who must undergo kidney dialysis. In all of these cases, a person does not receive adequate amounts of the vitamin for the body's needs. In the case of alcoholics, for example, alcohol replaces the calories they would be getting from food if they were not drinking so much. As a result, they do not get enough vitamin B₁ and other nutrients needed to stay healthy.

The early symptoms of beriberi include fatigue, irritability, poor sleep habits, memory loss, abdominal pain, loss of appetite, and constipation. As the disease progresses, it may produce damage to the peripheral nervous system that serves the arms, legs, feet, and hands, resulting in muscular atrophy (weakness and wasting of the muscles) and loss of sensation in the toes.

FOR FURTHER INFORMATION

Eades, Mary Dan. The Doctor's Complete Guide to Vitamins and Minerals. New York: Dell, 2000.

"Thiamine." Medline Plus. http://www.nlm.nih.gov/medlineplus/ency/article/002401.htm (accessed on November 15, 2005).

"Thiamine and Salts." International Programme on Chemical Safety. http://www.inchem.org/documents/pims/pharm/pimg015.htm (accessed on November 15, 2005).

"Vitamin B1." Welcome to Glactone. http://chemistry.gsu.edu/glactone/vitamins/b1/ (accessed on November 15, 2005).

Chemical Compounds