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10.32: Thiamin Deficiency & Toxicity

Thiamin deficiency is rare in developed countries, but still occurs in poorer countries where white (aka polished) rice is a staple food. During the polishing process, thiamin, and many other nutrients, are removed. Some people also have a mutation in THTR1 that causes them to become thiamin deficient1. Thiamin deficiency is known as beriberi, which, when translated, means "I can't, I can't." The symptoms of beriberi are illustrated in the link below.

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Beriberi

There are two major forms of beriberi: dry and wet. Dry beriberi affects the nervous system, with symptoms such as loss of muscle function, numbness, and/or tingling. Wet beriberi affects the cardiovascular system resulting in pitting edema, along with enlargement of the heart1. A picture of a person with beriberi is shown below.

Figure 10.321 A person suffering from beriberi2

Another group that is at risk for thiamin deficiency is alcoholics. There are three reasons why alcoholics are prone to becoming deficient3:

  1. Alcohol displaces foods that are better sources of thiamin
  2. Liver damage decreases TPP formation
  3.  Increased thiamin excretion

The thiamin deficiency found in alcoholics is known as Wernicke-Korsakoff Syndrome. Symptoms of this condition include paralysis or involuntary eye movement, impaired muscle coordination, memory loss and confusion3. The following video shows some of the symptoms of this condition.

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Video: Wernicke-Korsakoff Syndrome (First 1:50)

Thiamin toxicity has never been reported as a result of oral intake. Thus, there is little worry about thiamin toxicity4.

References & Links

  1.  http://www.nlm.nih.gov/medlineplus/e...cle/000339.htm
  2. http://en.wikipedia.org/wiki/File:Beriberi_USNLM.jpg
  3. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
  4.  Stipanuk MH. (2006) Biochemical, physiological, & molecular aspects of human nutrition. St. Louis, MO: Saunders Elsevier.