Classification and external resources
Beriberi is a disease caused by thiamine (vitamin B1) deficiency. It affects a variety of organs and systems of the body, including the nervous system, digestive system, heart, and muscles. If untreated, it is fatal.
Beriberi is not common in developed nations, but is associated with alcoholism and gastrointestinal disorders there. Beriberi is endemic, and rates can be quite high, in a number of developing nations, including areas of Asia where people subsist on polished rice, in which the outer, nutrient-rich husk is removed (Chamberllin and Narins 2005).
Beriberi reflects upon personal and societal responsibility. Individually, one must seek proper nutrition and avoid over-reliance on one particular food, whether it be unenriched white rice or alcohol. Societal responsibility includes the need for nutritional education and enrichment of products like white bread and white rice, as well as other activities showing proper concern for others. There are many cases of young migrant workers in Asia dying suddenly (shoshin beriberi) because of subsisting on white rice. Whether this is because of their own choice of this cheap staple food, or because it is supplied by the employer, nonetheless, employers have the responsibility to care for their workers.
Overview and prevelance
Thiamine (or thiamin) is one of the B vitamins, a group of chemically distinct, water-soluble vitamins that also includes riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, and others. Thiamine is essential in small amounts for human health. It is integral to the complex coordination of the Krebs cycle, which is the main biochemical pathway to extract energy from glucose, amino acids, and fat (Podel 1999), and it is needed for normal growth and development and to maintain proper functioning of the heart and the nervous and digestive systems. Thiamine serves as a co-enzyme in the pathway to synthesize NADPH and the pentose sugars deoxyribose and ribose, the later two of which are the sugars for DNA and RNA, respectively.
Since it is water-soluble, thiamine cannot be stored in the body; however, once absorbed, the vitamin is concentrated in muscle tissue. Among good sources of thiamine are various vegetables, including legumes and green peas, as well as liver, nuts, and yeast. The aleurone layer of unpolished rice is a rich source. In the developed countries, many foods are enriched with Vitamin B1.
Thiamine was first discovered in 1910 in Japan, as a result of research into how rice bran cured patients of beriberi. Until that time, it was a mystery why beriberi was affecting so many people of all ages in Asia, and only in the early 1900s was it realized that rice bran contained something to prevent it. In many Asian countries, there was a reliance on white (polished) rice as a staple food, with white rice produced by removal of the bran, which contains most of the thiamine.
Even today, beriberi is common in people whose diet consists mainly of white rice, which, when not enriched, contains little or no thiamine. In some areas of Asia, where white rice is a staple food, the rates of beriberi can be quite high—including up to 66 percent among low-income families in certain parts of Indonesia (Chamberlin and Narins 2005).
Thiamine deficiency is also correlated with a diet high in thiaminase-rich foods (thiaminase is an enzyme that metabolizes or breaks down thiamine), such as raw freshwater fish, raw shellfish, and ferns), as well as foods high in anti-thiamine factors, such as tea, coffee, and betel nuts (Higdon 2002).
In addition to systematic thiamine deficiency caused by malnutrition, this deficiency is also common in chronic alcoholics with impaired liver function. Thiamine deficiency is known (though rare) as a potential side effect of gastric bypass surgery. If a baby consumes the milk of a mother who suffers from thiamine deficiency, the child may develop beriberi.
Systemic thiamine deficiency can lead to myriad problems, including neurodegeneration, wasting, and death.
Types of beriberi
There are two main forms of the disease: wet beriberi and dry beriberi.
Wet beriberi primarily impacts the cardiovascular system, including the heart. It is sometimes fatal, as it causes a combination of heart failure and weakening of the capillary walls, which causes the peripheral tissues to become waterlogged.
These forms will appear in the same patient, but with one or the other dominant.
Chamberlin and Narins (2005) note two other main categories of the disease: shoshin and infantile beriberi. Shoshin is a form of wet (or cardiovascular) beriberi whereby there is sudden onset, rapid progression, and an often fatal collection of cardiovascular impacts. Infantile beriberi strikes babies generally between the age of one and four months who are breastfed by mothers deficient in thiamine.
The Wernicke-Korsakoff syndrome (cerebral beriberi) occurs in chronic alcoholics and affects the central nervous system.
Overall, symptoms of beriberi include weight loss, emotional disturbances, impaired sensory perception (Wernicke's encephalopathy), weakness and pain in the limbs, and periods of irregular heart rate. Edema (swelling of bodily tissues) is common. In advanced cases, the disease may cause heart failure and death.
Dry beriberi, which affects the nervous system, tends to produce symptoms of numbness, tingling, and burning pain in the extremities and cramping in the leg muscles, as well as difficulty with speech and sense of balance (Chamberlin and Narins 2005). Wet beriberi, which affects the cardiovascular system, includes symptoms of a fast heart beat, enlarged heart and liver, shortness of breath, swollen legs and feet, and lung congestion (Chamberlin and Narins 2005). Shoshin produces the same symptoms as wet beriberi, but with sudden onset and rapid progression. Infantile beriberi exhibits as difficulty sleeping, restlessness, diarrhea, swollen extremities, muscle wasting, and silent cry (Chamberlin and Narins 2005).
These symptoms largely are caused by abnormal metabolism of carbohydrates, resulting in decreased energy production, and injury to the heart and nervous system (Chamberlin and Narins 2005). Thiamine is needed for reactions that produce energy from glucose or convert glucose to fat.
The origin of the word is from a Sinhalese phrase meaning "I cannot, I cannot," showing the devastating impact on the muscles, and the cardiovascular and nervous systems.
Diagnosis includes taking a history of the patient to look for causes of deficiency, physical examination for expected signs (swelling, problems with balance, etc.), and laboratory testing to demonstrate thiamine deficiency (Chamberlin and Narins 2005).
A positive diagnosis test for thiamine deficiency can be ascertained by measuring the activity of transketolase in erythrocytes . Thiamine can also be measured directly in whole blood following the conversion of thiamine to a fluorescent thiochrome derivative.
Other laboratory measurements include tests for the chemicals lactate and pyruvate in the blood, which will be elevate in beriberi, and tests for the amount of thiamine passed into the urine, which will be low in cases of beriberi (Chamberlin and Narins 2005).
Diagnosis as beriberi may also be made by administering thiamine and see if the symptoms are resolved.
Treatment is with thiamine hydrochloride, either in tablet form, injection, or in severe cases intravenously (into a vein). Magnesium is usually administered as well, since it is required for proper functioning of thiamine (Chamberlin and Narins 2005). A rapid and dramatic recovery within hours can be made when this is administered to patients with beriberi, and their health can be transformed within an hour of administration of the treatment. Vitamin supplements and good nutrition in the diet is required subsequently.
- Chamberlin, S. L., and B. Narins. 2005. The Gale Encyclopedia of Neurological Disorders. Detroit: Thomson Gale. ISBN 078769150X
- Higdon, J. 2002. “Thiamin.” Micronutrient Information Center (Oregon State University: Linus Pauling Institute). Retrieved July 19, 2007.
- Podel, R. N. 1999. “Thiamine's mood-mending qualities.” Nutrition Science News. Retrieved July 19, 2007.
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