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 originates in the lowest levels of the food web. Certain species of bacteria, phytoplankton, fungi and even some plants are responsible for synthesizing thiamine from other precursor compounds. From there, thiamine makes its way through both the animal and plant kingdoms.
The human deficiency disease, beriberi, has two main forms.
In Paralytic or nervous beriberi ("dry" beriberi), there is a gradual degeneration of the long nerves, of the legs and the arms, resulting in numbness, tingling and/or exaggerated reflexes, with associated atrophy of muscle.
Cardiac ("wet" beriberi) is a more acute form with symptoms including racing heart rate, enlarged heart, breathing problems and oedema resulting in large part from cardiac failure and poor circulation.
There is also Gastrointestinal beriberi, with nausea, vomiting, abdominal pain and lactic acidosis; and Cerebral beriberi — Wernicke's encephalopathy, cerebellar dysfunction causing abnormal eye movements, ataxia (lack of muscle coordination) and cognitive impairments. If left untreated, it can progress to Korsakoff's psychosis, a chronic brain disorder that presents as amnesia, confusion, short-term memory loss, confabulation (fabricated or misinterpreted memories) and in severe cases, seizures
Beriberi was first shown conclusively to be a nutritional disease by the Japanese naval surgeon Admiral Takaki. In 1878 the diet in the Japanese navy considered almost entirely of milled rice, and about 30% of the sailors suffered from beriberi each year.
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.