Vitamin B1
Vitamin B1 (thiamin) is essential for the metabolism of carbohydrates (to produce energy) and for normal nerve and heart function.
Vitamin B1 Deficiency
Vitamin B1 (thiamin) deficiency may result from a deficiency in the diet. People whose diet consists mainly of polished (refined) white rice are at risk of vitamin B1 deficiency, because polishing removes almost all of the vitamins. Alcoholics, who often substitute alcohol for food, are at high risk of developing this deficiency.
Symptoms
Early symptoms are vague. They include fatigue, irritability, memory impairment, loss of appetite, sleep disturbances, abdominal discomfort, and weight loss. Eventually, a severe vitamin B1 deficiency (beriberi) may develop, characterized by nerve, heart, and brain abnormalities.
Beriberi causes different symptoms in different people. One form, called dry beriberi, causes nerve and muscle abnormalities. Symptoms include a prickling (pins-and-needles) sensation in the toes, a burning sensation in the feet that is particularly severe at night, and pain, weakness, and wasting (atrophy) of muscles in the legs.
Wet beriberi causes heart abnormalities. Symptoms include a high output of blood from the heart, a fast heart rate, and dilation of blood vessels, causing the skin to be warm and moist. Because the heart cannot maintain the high output, heart failure eventually develops, causing fluid accumulation in the legs (edema) and in the lungs (congestion). As a result, blood pressure may fall, leading to shock and death.
Brain abnormalities due to vitamin B1 deficiency occur primarily in alcoholics. Brain abnormalities may develop when a chronic vitamin B1 deficiency is suddenly worsened by a rapid, substantial decrease in the vitamin B1 level (which can be caused by an alcoholic binge) or by a sudden increase in vitamin B1 requirements (which may occur when an undernourished alcoholic is fed intravenously).
Brain abnormalities may develop in two stages: an early stage called Korsakoff's syndrome and a later stage called Wernicke's encephalopathy. Together, these stages are called the Wernicke-Korsakoff syndrome (see Section 6, Chapter 82). Korsakoff's syndrome causes memory loss, and Wernicke's encephalopathy causes mental confusion, difficulty walking, and eye problems (including nystagmus and paralysis of the eyes). If Wernicke's encephalopathy is not promptly treated, symptoms may worsen, resulting in coma and even death.
Diagnosis and Treatment
The diagnosis is based on symptoms. Tests to confirm the diagnosis are not readily available. All forms of the deficiency are treated with vitamin B1 supplements.
Wernicke's encephalopathy, a medical emergency, is treated with high doses of vitamin B1 for several days. When people who may be alcoholics must be fed intravenously, they are often given vitamin B1 supplements as a preventive measure. For people who have the Wernicke-Korsakoff syndrome, recovery is often incomplete because some brain damage may be permanent. Symptoms of beriberi may recur years after apparent recovery.
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