Overview
Beriberi is a disease caused by a severe deficiency of thiamine (vitamin B1), a vitamin the body needs to turn food into energy. It affects the heart and circulation (wet beriberi) or the nerves (dry beriberi). Severe thiamine deficiency can also affect the brain, causing Wernicke's encephalopathy.
Beriberi was once common in parts of Asia where people mainly ate polished white rice, which has had its thiamine-rich outer layer removed. Today, it is most often seen in people with alcohol use disorder, severe malnutrition, prolonged vomiting, eating disorders, after bariatric surgery, or in babies breastfed by thiamine-deficient mothers. Beriberi can be life-threatening, especially wet beriberi in infants, but it responds rapidly to thiamine treatment.
When to get urgent help
Seek emergency care for confusion, unsteady walking with eye movement problems, severe breathlessness, swelling with a fast heartbeat, or a baby who is feeding poorly, vomiting or has a weak cry.
Causes and risk factors
- Diet low in thiamine: reliance on polished white rice or refined flour
- Alcohol use disorder: reduces intake, absorption and storage of thiamine
- Malnutrition and starvation
- Prolonged vomiting, including hyperemesis gravidarum
- Eating disorders
- Bariatric (weight loss) surgery
- Chronic diarrhoea and malabsorption
- Dialysis and high-dose diuretics, which increase loss
- High intake of tea, coffee or raw fish, which contain thiamine-destroying enzymes (thiaminases) in some cases
- Infants breastfed by thiamine-deficient mothers
How it develops (pathophysiology)
Normal role of thiamine
Thiamine is a water-soluble vitamin found in whole grains, legumes, pork, nuts and seeds. The body stores only small amounts, enough for about two to three weeks. In cells, thiamine is converted into thiamine pyrophosphate, an essential co-factor for enzymes involved in energy production:
- Pyruvate dehydrogenase, which links glucose breakdown to the Krebs cycle
- Alpha-ketoglutarate dehydrogenase, in the Krebs cycle
- Transketolase, in the pentose phosphate pathway
These enzymes are vital for producing ATP (cellular energy), especially in tissues with high energy needs, such as the heart, nerves and brain.
What goes wrong
- Energy failure: without thiamine, cells cannot efficiently convert glucose into energy. Pyruvate builds up and is converted into lactate, causing lactic acidosis.
- Nerve damage: nerve cells, which rely heavily on glucose metabolism, suffer energy shortage, leading to degeneration of peripheral nerves and their insulating myelin (dry beriberi).
- Heart and circulation: energy failure in heart muscle and blood vessels causes widening of blood vessels (vasodilation), lowering resistance. The heart pumps more blood to compensate (high-output heart failure), but the energy-starved muscle eventually weakens, causing fluid retention and swelling (wet beriberi). A rapid, severe form called Shoshin beriberi causes sudden heart failure and shock.
- Brain damage: areas of the brain with high thiamine needs, such as the mammillary bodies, thalamus and brainstem, are damaged, causing Wernicke's encephalopathy and, if untreated, permanent memory loss (Korsakoff syndrome).
Giving glucose to a thiamine-deficient person can worsen symptoms, because glucose metabolism uses up the remaining thiamine.
Why the symptoms happen
- Numbness, tingling, burning and weakness in the legs reflect peripheral nerve damage.
- Muscle wasting and difficulty walking reflect nerve and muscle damage.
- Breathlessness, fast heartbeat and swelling reflect high-output heart failure.
- Confusion, unsteady walking and abnormal eye movements reflect Wernicke's encephalopathy.
- In babies: hoarse cry, vomiting, restlessness and rapid heart failure.
How treatment acts on the mechanism
Thiamine replacement, often given by injection in severe cases, restores enzyme function and energy production. Wet beriberi can improve dramatically within hours to days. Nerve damage improves more slowly, and brain damage may be partly permanent if treatment is delayed. Treating the cause, such as alcohol use or malnutrition, prevents recurrence.
Types
- Wet beriberi: affects the heart and circulation
- Dry beriberi: affects peripheral nerves
- Shoshin beriberi: acute severe heart failure
- Infantile beriberi: in breastfed babies of thiamine-deficient mothers
- Wernicke-Korsakoff syndrome: brain involvement
Signs and symptoms
Dry beriberi:
- Numbness, tingling or burning in the feet and hands
- Leg weakness and cramps
- Difficulty walking
- Muscle wasting
Wet beriberi:
- Breathlessness, especially on exertion or lying down
- Fast heartbeat
- Swelling of the legs
- Tiredness
Wernicke's encephalopathy:
- Confusion
- Unsteady walking
- Eye movement problems and double vision
Infants:
- Poor feeding, vomiting
- Hoarse or silent cry
- Restlessness
- Rapid breathing, swelling and heart failure
How it is diagnosed
- Clinical suspicion based on symptoms and risk factors
- Blood tests: thiamine level or erythrocyte transketolase activity, lactate
- Response to thiamine treatment often confirms the diagnosis
- Echocardiogram for heart involvement
- Nerve conduction studies for neuropathy
- MRI brain for Wernicke's encephalopathy
Treatment should not be delayed while waiting for tests.
Possible complications
- Heart failure and shock
- Permanent nerve damage
- Wernicke's encephalopathy and Korsakoff syndrome
- Death, especially in infants and in Shoshin beriberi
Goals of treatment
Treatment aims to restore thiamine levels quickly, reverse heart failure and nerve damage, prevent brain damage and address the underlying cause.
Medicines
- Thiamine, by injection in severe or suspected Wernicke's encephalopathy, then by mouth
- Thiamine before glucose in at-risk people
- Treatment of heart failure
- Other vitamins and minerals, including magnesium, which is needed for thiamine to work
Other treatments
- Nutritional rehabilitation
- Alcohol treatment services
- Physiotherapy for nerve damage
- Treatment of underlying causes, such as vomiting
Living with it and prevention
- Eat a varied diet including whole grains, legumes, nuts, seeds and meat
- Use enriched or parboiled rice where rice is a staple
- Limit alcohol
- Thiamine supplements for people at high risk, such as those with alcohol use disorder or after bariatric surgery
- Ensure pregnant and breastfeeding women have enough thiamine
Monitoring and follow-up
Symptoms and nutritional status are monitored during recovery. People at ongoing risk may need long-term supplements.
Outlook
Wet beriberi usually responds dramatically to treatment. Dry beriberi improves more slowly. Brain damage may be permanent if treatment is delayed. Infantile beriberi can be fatal without prompt treatment.
Special considerations
- Infants: wet beriberi can progress rapidly to death
- Pregnancy: hyperemesis gravidarum can cause thiamine deficiency
- People with alcohol use disorder: high risk of Wernicke's encephalopathy
