All organisms need thiamine, also known as Vitamin B1. In animals, enzymes interact with thiamine to generate cellular energy. Without sufficient amounts of thiamine, fundamental metabolic processes start to fail, causing neurological disturbances, reproductive problems and increased mortality.
Beriberi is a humn nutritional disorder caused by a deficiency in vitamin B1, presenting cardiac and neurological symptoms. Infantile beriberi, an important problem in breast-fed infants whose mothers milk is deficient in thiamine, can lead to heart failure. Starving children bodies often show signs of beriberi.
Thiamine deficiency subsists in situations where imbalanced diets are prevalent (rice-eating countries, chronic alcoholism, etc). Refining of foods like sugar, flour and rice removes the thiamine.
Thiamine deficiency has been identified in dozens of animal species and is now suspected of driving declines in wildlife populations across the northern hemisphere. The transfer of thiamine up the food chain may be blocked by a number of factors, including the overabundance of thiaminase, an enzyme that destroys thiamine. Thiaminase is naturally present in certain microorganisms, plants and fish that have adapted to use it to their advantage.