There are two major manifestations of thiamine deficiency: cardiovascular disease (wet beriberi) and nervous system disease ("dry beriberi" and Wernicke-Korsakoff syndrome). Both types are most often caused by excessive alcohol consumption. Symptoms of dry beriberi include pain, tingling, or loss of sensation in hands and feet (peripheral neuropathy), muscle wasting with loss of function or paralysis of the lower extremities, and potential brain damage and death. Wet beriberi is characterized by swelling, increased heart rate, lung congestion, and enlarged heart related to congestive heart failure. Beriberi has become rare in the United States because most foods are now vitamin-enriched, which means that a normal diet contains adequate amounts of thiamine. As a result, beriberi now occurs primarily in patients who abuse alcohol, because drinking heavily can lead to malnutrition and poor absorption and storage of thiamine. This is the cause of Wernicke-Korsakoff syndrome, which is alcohol-related brain damage affecting language and thinking. Beriberi can also occur in breast-fed infants when the mother has an inadequate intake of thiamine. It can also affect infants fed unusual formulas with inadequate thiamine supplements. Others at risk for beriberi include patients undergoing dialysis, patients receiving high doses of diuretics, and people in developing countries with limited diets who consume milled rice. In addition, there is a rare condition known as genetic beriberi. This is an inherited condition in which affected people lose the ability to absorb thiamine from foods. This can happen slowly over time and manifest as an adult. Since beriberi may not be considered in nonalcoholics, this diagnosis is often missed. Nervous system symptoms are caused by the degeneration of nerve fibers and their insulation (myelin sheath). Heart failure is the most common cause of death in people with beriberi.
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