Beriberi is a disease caused by a severe deficiency of vitamin B1 (thiamine), a nutrient your body needs to convert food into energy. Without enough thiamine, cells can’t properly metabolize carbohydrates, and the organs that burn the most fuel, your heart and nervous system, are the first to suffer. The disease takes two main forms: one that damages the nerves and one that damages the heart.
How Thiamine Deficiency Damages the Body
Thiamine is a building block for enzymes involved in several critical metabolic processes. In its active form, it helps power the cycle your cells use to produce energy from glucose. It also plays a role in making neurotransmitters and in the pathway cells use to build DNA precursors. When thiamine levels drop, these enzyme systems slow down, mitochondria malfunction, and cells that depend heavily on glucose begin to die.
The brain is especially vulnerable. About 80% of the thiamine in your central nervous system is dedicated to glucose metabolism. When supply runs low, neurons in specific brain regions starve and degenerate. This is why beriberi so often shows up as neurological problems first, particularly tingling, numbness, and muscle weakness in the legs and feet.
Dry Beriberi: The Neurological Form
Dry beriberi primarily affects the peripheral nerves, the network that carries signals between your brain and your limbs. Early symptoms include a pins-and-needles sensation in the feet and lower legs, difficulty walking, and muscle weakness that gradually moves upward. Over time, reflexes diminish and muscles can begin to waste. Some people also experience pain, burning sensations, or a loss of coordination that makes everyday tasks like buttoning a shirt difficult.
The word “dry” distinguishes this form from the version that causes fluid buildup. In dry beriberi, the heart is largely spared. The damage is concentrated in the nerves, and if caught early enough, it can be reversed with thiamine replacement.
Wet Beriberi: The Cardiovascular Form
Wet beriberi targets the heart and circulatory system. Without adequate thiamine, the heart muscle weakens and blood vessels dilate, leading to a dangerous drop in the heart’s pumping efficiency. The body compensates by retaining fluid, which causes swelling (edema) in the legs, shortness of breath, and a rapid heart rate. In severe cases, wet beriberi can progress to congestive heart failure.
A particularly acute and life-threatening variant, sometimes called Shoshin beriberi, can cause cardiovascular collapse within hours. This form is rare but requires emergency treatment.
Infantile Beriberi
Babies can develop beriberi when they are breastfed by a mother who is thiamine-deficient, or when they are fed formula that lacks adequate thiamine. Infantile beriberi typically appears in the first few months of life and can progress rapidly. Symptoms include irritability, vomiting, a distinctive high-pitched cry, and in severe cases, heart failure or seizures. Because infants can’t describe what they’re feeling, the condition is sometimes missed until it becomes serious.
Who Is Most at Risk
In developed countries, beriberi occurs most often in people with chronic alcohol use. Heavy drinking creates a double problem: it leads to poor nutrition, and alcohol itself interferes with the body’s ability to absorb and store thiamine. This combination makes people with alcohol dependence the single highest-risk group.
Other populations at elevated risk include:
- People on dialysis, because the filtering process removes water-soluble vitamins from the blood
- People taking high-dose diuretics, which increase thiamine loss through urine
- People who have had bariatric surgery, which can reduce nutrient absorption
- People with chronic intestinal diseases such as celiac disease or tropical sprue, which impair absorption in the gut
- People with severe malnutrition, including those on very restrictive diets
In rare cases, beriberi is genetic. Some people inherit a condition that prevents their bodies from absorbing thiamine from food, regardless of how much they eat.
Wernicke-Korsakoff Syndrome
When thiamine deficiency goes untreated and reaches the brain, it can cause a two-stage condition called Wernicke-Korsakoff syndrome. The first phase, Wernicke encephalopathy, involves confusion, difficulty with eye movements, and loss of balance. If thiamine is replaced at this stage, many of these symptoms can improve.
Without treatment, the damage can progress to Korsakoff syndrome, a chronic condition marked by severe memory loss, an inability to form new memories, and a tendency to fill gaps in memory with fabricated details (confabulation). Korsakoff syndrome is often permanent. This progression is most commonly seen in people with long-term alcohol use, and it represents the most serious neurological consequence of thiamine deficiency.
Diagnosis
Doctors diagnose beriberi based on symptoms, dietary history, and a blood test that measures thiamine levels. The standard test checks for thiamine diphosphate in whole blood. Normal values fall between 70 and 180 nmol/L, and anything below 70 nmol/L suggests deficiency, according to Mayo Clinic Laboratories reference ranges. Your doctor will also look for signs of conditions that commonly accompany thiamine deficiency, such as alcohol use disorder or malnutrition, and may order additional blood work or imaging to rule out other causes of your symptoms.
Treatment and Recovery
The good news about beriberi is that it responds quickly to thiamine replacement. For mild deficiency, the World Health Organization recommends 10 mg of oral thiamine daily for one week, then 3 to 5 mg per day for at least six weeks. Severe cases require higher doses delivered by injection: 50 to 100 mg for adults (25 to 30 mg for infants), followed by about a week of daily injections and then a longer course of oral supplements.
Heart symptoms from wet beriberi often begin improving within hours to days of starting treatment. Nerve damage from dry beriberi takes longer. Some people see significant recovery within weeks, while others need months, and the degree of recovery depends on how long the deficiency lasted before treatment began. Long-standing nerve damage may not fully reverse.
Thiamine-Rich Foods
Most adults need about 1.1 to 1.2 mg of thiamine per day. Because your body can’t store large reserves of this vitamin (it’s water-soluble and excess is excreted in urine), you need a steady daily supply. Good dietary sources include pork, which is one of the richest natural sources, along with whole grains, fortified cereals, black beans, lentils, sunflower seeds, and trout. White rice that has been enriched is also a reliable source, though unfortified polished rice, the dietary staple historically linked to beriberi outbreaks in Asia, contains very little.
For most people eating a varied diet, getting enough thiamine is straightforward. The risk rises when diet becomes severely restricted, when absorption is impaired by illness or surgery, or when alcohol use displaces nutritious food and blocks the vitamin’s uptake at the same time.