140 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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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.
Another group that is at risk for thiamin deficiency is alcoholics. There are three reasons why alcoholics are prone to becoming deficient3:
- Alcohol displaces foods that are better sources of thiamin
- Liver damage decreases TPP formation
- 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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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/ency/article/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
Links
Beriberi – http://www.moondragon.org/health/graphics/beriberi1.jpg
Wernicke-Korsakoff Syndrome – http://www.youtube.com/watch?v=wDcyBXJAZNM