Thiamine, or vitamin B-1, supports the health of muscle cells and the nervous system, and it regulates the flow of electrolytes that move in and out of these cells, says Mayo Clinic. Thiamine is also necessary for digestion and the metabolism of carbohydrates.
Thiamine helps people withstand stress by bolstering the immune system, according to the University of Maryland Medical Center. Thiamine is found in both plant and animal foods, and though it is water soluble and doesn't stay in the body for long, a deficiency is rare. However, people with conditions such as alcoholism, Crohn's disease and anorexia may need supplemental thiamine. Patients who undergo kidney dialysis may also lack thiamine. People who are very deficient in thiamine can't digest carbohydrates, which leads to diseases such as beriberi and Wernicke-Korsakoff syndrome.
Wernicke-Korsakoff syndrome has two components, says the University of Maryland Medical Center. Wernicke disease damages both the central and peripheral nervous systems, and Korsakoff syndrome causes damage to the nerves and memory loss. Some studies indicate that thiamine, when it is taken with other nutrients, lowers the risk of cataracts. Other researchers believe that thiamine helps improve some symptoms of Alzheimer's disease, since thiamine deficiency leads to dementia in people suffering from Wernicke-Korsakoff syndrome. Thiamine also seems to protect against heart failure and depression.