Beriberi

Summary

• Beriberi is caused by a deficiency of the vitamin thiamine or vitamin B₁.
• In developed countries, beriberi is seen mainly in alcoholics and people who eat unbalanced diets (e.g. patients suffering from eating disorders such as anorexia nervosa and orthorexia). Individuals who have undergone bariatric surgery for weight loss and do not take the required vitamin supplements may develop symptoms of beriberi (painful neuropathy due to thiamine deficiency).
• In the developing world it is common among those whose staple diet is machine-milled rice or highly refined staples such as white, sifted, unfortified  maize meal.
• Thiamine is present in most plant foods, particularly in unprocessed cereals and grain products fortified with thiamine. Brewer’s yeast, liver and pork are also good sources of thiamine.
• Beriberi affects the heart (wet beriberi) and the nervous system (dry beriberi).
• Treatment involves the provision of adequate amounts of thiamine and correction of unbalanced eating habits.

Definition

Beriberi is a condition which results from a deficiency of the vitamin thiamine or vitamin B₁.

Cause

Beriberi is caused by a deficiency of thiamine. This vitamin is synthesised by a variety of plants and microorganisms, but not normally by animals. Small amounts may be synthesised by microorganisms in the gut.

About 5mg of thiamine a day can be absorbed by the gut. About 25 - 30mg is stored in the body.

Large amounts are present in skeletal muscles (about one half of body stores), heart, liver, kidneys and brain.

The recommended daily allowance of thiamine in men is between 1.2 - 1.5 mg and in women between 1 - 1.2 mg per day.

Thiamine is widely present in foods and is only absent from fats, cassava and refined sugar. The outer layers of cereal grains are particularly rich in thiamine, so machine milled rice and other highly processed staple foods such as unfortified, sifted, white maize meal, are poor sources of the vitamin. Since 2003, thiamine is added to maize meal and wheat flour in South Africa.

Who gets it and risk factors

In developed nations, thiamine deficiency occurs in alcoholics, individuals who eat unbalanced diets, such as patients suffering from anorexia nervosa or orthorexia, the ever increasing number of individuals who have had bariatric surgery for the treatment of obesity, and in patients who are undergoing dialysis for kidney disease or receiving total parenteral nutrition (TPN) because of multivitamin infusion shortage. In 2005, an outbreak of life-threatening thiamine deficiency was reported in infants in Israel who received a defective soy-based formula which was deficient in thiamine.

In developing countries, the disorder is usually due to the consumption of highly refined staple foods such as milled rice and unfortified sifted white rice. An outbreak of beriberi was reported in Thailand in 2005 among commercial fishermen, which was primarily attributed to malnutrition caused by eating only seafood and polished rice for almost two months.

Daily needs for thiamine decrease when fat forms a large part of the diet and increase when the diet is high in carbohydrates. Pregnancy, lactation, an overactive thyroid and fever increase the requirement for thiamine.

Accelerated loss of thiamine from the body may occur with diuretic treatment, haemodialysis and diarrhoea.

Defective absorption can occur in malabsorption states, alcoholism, chronic malnutrition and folate deficiency.

Signs and Symptoms

There are two major clinical manifestations of beriberi. One involves the cardiovascular system (wet beriberi), while the other affects the nervous system (dry beriberi and the so-called Wernicke-Korsakoff syndrome).

The typical patient has mixed symptoms, involving both the cardiovascular and nervous systems. Which set of symptoms is most prevalent depends on the duration and severity of the deficiency, the amount of physical exertion and the energy intake.

A lot of physical activity, a high carbohydrate diet and a moderate degree of chronic deficiency lead to wet beriberi. The opposite favours the development of dry beriberi.

Early symptoms of deficiency are fatigue, irritation, poor memory, sleep disturbances, pain in the chest, loss of appetite, abdominal discomfort and constipation.

Dry beriberi results in pins and needles in the toes, burning of the feet (particularly severe at night), calf muscle cramps and pains in the legs. The arms may become involved later in the illness.

Beriberi involving the brain (Wernicke-Korsakoff syndrome) results when short-term severe deficiency is superimposed on chronic deficiency. The early stage is called Korsakoff syndrome and the person is confused, has difficulty talking and confabulates (makes things up to cover for loss of memory).

Wernicke’s encephalopathy is the second part of the syndrome and results when beriberi involving the brain is not treated. Blood flow to the brain is decreased and coma and eventually death result.

Cardiovascular beriberi (wet beriberi) takes two forms. In the first form the person experiences a fast heart beat, sweating and the skin is warm. As the disease progresses, heart failure occurs.

The second form is called Shoshin disease and is very rare. In this case the onset of symptoms is sudden and overwhelming, and death through total cardiovascular collapse may occur in days or even hours.

Diagnosis

There are various biochemical tests to detect thiamine deficiency. These include the measurement of blood thiamine and other related substances and the measurement of the amount of thiamine excreted in the urine.

The most reliable diagnostic investigation is the measurement of whole blood or red blood cell transketolase activity. Transketolase is an enzyme for which thiamine acts as a co-enzyme (enhancing its activity in a particular metabolic pathway). If the activity of this enzyme increases as a result of adding another form of thiamine –– thiamine diphosphate –– (TPP), this is called the TPP effect and is expressed as a percentage. If the activity of the enzyme is increased by more than 15% by the added thiamine diphosphate, then the person is almost certainly deficient in thiamine.

Another way of diagnosing thiamine deficiency is by giving someone with the clinical signs of beriberi thiamine and seeing how they respond. The person’s condition will usually improve rapidly when they suffer from cardiovascular beriberi, with a reduction in the size of the heart within one to two days.

Prevention

Beriberi can be prevented by an adequate intake of thiamine, which therefore requires eating a balanced diet or ensuring that patients at risk of thiamine deficiency (anorexia nervosa, orthorexia, post-bariatric surgery) are given vitamin B complex supplements that contain thiamine. Care must be taken to ensure that patients receiving TPN and formula-fed infants receive feeds that have an adequate thiamine content. 

Treatment

Thiamine deficiency is treated by giving large amounts of the vitamin as soon as a deficiency is suspected.

50mg a day should be given by intramuscular injection for several days. After this, 2.5 - 5 mg a day can be given by mouth.

Larger amounts are not usually absorbed. All patients should also receive other water-soluble vitamins in the correct dose, because B complex vitamins, including thiamine, work more efficiently when given in combination .

When to call the doctor

If you think that your diet could be deficient in thiamine and you start to experience any of the symptoms described above, you should speak to your doctor.

If you know an alcoholic who suffers from any of these symptoms then he or she may be suffering from thiamine deficiency and is in need of medical help.

Previously reviewed by Dr Andrew Rose-Innes, MD, Department of Neurology, Yale University School of Medicine, New Haven, 2007

Reviewed by Dr Ingrid van Heerden, DietDoc, Health24.com, February 2011