Thiamin, or vitamin B1, deficiency is rare now that many foods today come fortified or enriched with vitamins. Conditions known as beriberi and Wernicke-Korsakoff syndrome occur because of thiamine deficiency. Thiamine deficiency is highly avoidable for most, although some are born with a condition known as genetic beriberi in which the body loses its ability to absorb thiamine in foods. Doctors treat patients who have thiamine deficiency with vitamin supplements.
Early symptoms of thiamine deficiency are easy to miss because they are so nonspecific. They can include fatigue, irritability, sleep disturbances and even abdominal discomfort -- all symptoms that can easily describe a host of other conditions and ailments.
There are two types of beriberi. Wet beriberi affects your cardiovascular system, and dry affects your central nervous system. Wet beriberi symptoms include shortness of breath after activity, lower leg swelling and difficulty walking and numbness in your hands and feet. Dry beriberi can cause paralysis in your lower legs and cause vomiting as well as uncontrollable eye movements and speech difficulties.
Wernicke's encephalopathy and Korsakoff syndrome are different conditions that go hand in hand and cause brain damage because of a lack of thiamine. Korsakoff syndrome occurs when the thiamine deficiency impacts the part of the brain that deals with memory. Symptoms can include an inability to make new memories or to remember old ones, hallucinations and making up stories. Wernicke's encephalopathy causes damage to the thalamus and hypothalamus brain regions and can cause leg tremors and vision changes such as double vision, eyelid drooping and back-and-forth eye movements similar to those of dry beriberi.
These conditions are most common in alcoholics because extra alcohol makes it harder for your body to absorb and store thiamine. In developing countries, thiamine deficiency also occurs among people whose diet mostly consists of white rice or highly refined carbohydrates. People on dialysis or those who abuse diuretics are also at increased risk for thiamine deficiency.