Vitamin B1, sometimes also called Thiamine, was one of the first compounds recognized as a vitamin. Thiamine is involved in many body functions, including nervous system and muscle function, the flow of electrolytes in and out of nerve and muscle cells, digestion, and carbohydrate metabolism. It prevents nerve damage, supports a healthy cardiovascular system, boosts immunity, treats alcoholism, prevents brain disorders, enhances learning, helps keep a positive mood, and helps prevent vision problems. Very little thiamine is stored in the body and depletion can occur within 14 days. According to the USDA, the RDA for adults (19 years and older) is 1.2 mg/day for men and 1.1 mg/day for women and 1.4 mg/day for pregnant or breastfeeding women of any age. Severe thiamine deficiency may lead to serious complications involving the nervous system, brain, muscles, heart, and stomach and intestines. The clinical signs of a thiamine deficiency include: Anorexia or rapid weight loss, poor appetite, colitis, ongoing digestive problems such as diarrhea, nerve damage, nerve inflammation (neuritis), fatigue, decrease in short-term memory, confusion, irritability, muscle weakness, mental changes such as apathy or depression and cardiovascular effects such as an enlarged heart. Overdosing on thiamine, or vitamin B-1, is rare but can cause severe symptoms. Mild symptoms of an overdose include weakness and a headache. In some cases, high vitamin B1 levels can cause a rapid, irregular heartbeat and low blood pressure. These symptoms can lead to cardiac problems. Some patients will develop a low blood pressure and convulsions.