Thiamine deficiency can develop within 2-3 months of a deficient intake and can cause disability and death.
Thiamine is required for the production of ribose, RNA, DNA, nicotinamide adenine dinucleotide (NAD), and adenosine triphosphate (ATP). It is particularly important in tissues that are highly metabolically active, including neurons, cardiac myocytes, and erythrocytes, all of which rely on glucose as a main energy substrate.
Thiamine deficiency leads to impaired glucose metabolism, decreased delivery of oxygen by red blood cells, cardiac dysfunction, failure of neurotransmission, and neuronal death.
There are 2 major manifestations of thiamine deficiency: cardiovascular disease (wet beriberi) and nervous system disease (dry beriberi and Wernicke–Korsakoff syndrome).
Wet beriberi: mainly affects the cardiovascular system, causing poor circulation and fluid buildup in the tissues. Usually presents as predominantly right sided heart failure associated with a high cardiac output or less frequently as cardiovascular collapse.
Dry beriberi: primarily affects the nervous system, leading to the degeneration of the nerves.
The earliest symptoms of thiamine deficiency are nonspecific and include fatigue, irritation, poor memory, sleep disturbances, precordial pain, anorexia, abdominal discomfort and constipation.
The disorder (or spectrum of disorders) is classically associated with a diet consisting largely of polished rice (oriental beriberi), but may also arise if highly refined wheat flour forms a major part of the diet, in alcoholics, and in food faddists (occidental beriberi).
Beriberi: Causes and manifestations
