Beriberi is a condition that arises with deficiency of the vitamin known as thiamine, less frequently referred to as vitamin B1. It arises with consuming diets that are low or deficient in thiamine, conditions that affect absorption of thiamine or increased utilization or loss of thiamine. It is one of the commonly seen deficiencies among alcoholics and with extreme dieting. However, beriberi can occur in any person of any age. Thiamine deficiency affects the entire body with the nerves, heart and blood vessels being the most affected over time. Beriberi is easily treated with thiamine supplementation.
Incidence of Beriberi
Overall beriberi is uncommon in the general population in developed nations and the incidence is difficult to estimate. Thiamine deficiency is largely prevented through the fortification of many widely consumed foods. When beriberi is seen, it is usually due to underlying problems compromising good nutrition, like chronic alcoholism and fad diets with extreme calorie restriction. The higher incidence of thiamine deficiency in the general population is seen in developing nations with the highest incidence noted in refugee camps.
Functions of Thiamine
Thiamine pyrophosphate is the biologically active form of thiamine. It has a wide variety of functions in the human body. It has a major impact on metabolism, the brain and nerves, the heart and blood vessels and the gut. However, thiamine, either directly or indirectly, impacts on almost every cell in the body in some way or the other.
- Thiamine plays a role in carbohydrate metabolism and energy production.
- Thiamine assists in the conduction of impulses in nerves and contraction of muscles.
- Thiamine acts as a co-enzyme in various processes by facilitating the action of enzymes.
- Thiamine aids in the production of stomach acid which is essential for proper digestion.
- Thiamine is important for the structure of genetic material – DNA and RNA.
Sources of Thiamine
Thiamine is a water soluble vitamin that is absorbed from the small intestine. It is actively or passively absorbed into the blood stream and the body has a total pool of about 30mg (milligrams) of thiamine. Since the body cannot produce thiamine and store a very small quantity, it is important to source the vitamin on a regular basis from foods.
Thiamine is found in abundance in several foods including meats, animal products, vegetables and grains. However, there are some foods that contain enzymes that can breakdown thiamine and therefore hamper the sourcing of the vitamin from food. Overall beriberi is rare because many foods are fortified with thiamine so even a diet that lack thiamine-rich foods may not necessarily lead to beriberi.
Foods to Eat
A balanced diet is usually sufficient to prevent and even treat a thiamine deficiency. The following foods are have moderate to high amounts of thiamine.
- Meat, fish and poultry
- Milk and dairy products
- Fruit juices
Although certain foods, like leafy green vegetables, nuts and orange juice, is more abundant in thiamine, patients should be encouraged to eat a wide range of foods to prevent other deficiencies rather than focusing solely on thiamine.
Foods to Avoid
Certain foods hamper thiamine absorption or breakdown thiamine. These foods should NOT be avoided entirely but eaten in moderation. A person who maintains a balanced diet with a wide variety of foods can eat all of the foods below without risking a thiamine deficiency. Foods that affect thiamine stores includes :
- Fresh fish
- Shellfish – shrimp, mussels and clams
- Raw meat
- Millet rice
- Refined carbohydrates
- Saturated fats
Foods that are cooked or sterilized by pasteurisation and radiation lack thiamine which is destroyed by these processes.
Types of Beriberi
There are broadly two types of beriberi – dry and wet.
Dry beriberi is a condition where the brain and nerves are affected due to a deficiency of thiamine. The level of neurological dysfunction can vary. It is largely caused by the loss of the myelin sheath that normally insulates nerves. In alcoholics there may be even more severe implications known as Wernicke’s encephalopathy which can lead to Korsakoff syndrome. Although these conditions are related to thiamine deficiency, chronic alcoholism also has a host of effects on the body including the functioning of the nervous system.
Wet beriberi is a condition where the heart and blood vessels are affected due to a thiamine deficiency. It is largely due to vasodilation (widening of the blood vessels), thereby reducing peripheral resistance. The heart has to work harder in order to maintain the blood pressure and ensure an adequate venous return. Water and electrolytes are retained and there is gradual development of swelling throughout the body, mainly in the legs, abdomen and arms. The heart becomes strained from having to constantly pump harder in order to maintain the cardiac output.
Symptoms of Beriberi
The first symptoms of beriberi is weakness or fatigue. It is severe fatigue that is uncharacteristic for a person’s level of daily activity or age. It is accompanied by a degree of apathy – lack of interest in life or other activities that were previously enjoyable. Often patients are diagnosed with depression at this point. The patient may be irritable, have difficulty concentrating and experience constant drowsiness.
All of these symptoms appear to further support a diagnosis of depression. A lack of appetite, nausea and abdominal pain are other non-specific symptoms that may be seen in the early stages. The first symptoms may be noticed as early as 1 week after ceasing thiamine intake although there may be small stores still present in the body.
Symptoms of Dry Beriberi
- Unusual sensations such as tingling, prickling and/or numbness in both legs. This means that a person’s ability to feel pressure, temperature and pain.
- Some patients may experience burning pains in the limbs.
- Poor coordination of the limbs may be seen with a person experiencing difficulty in determining the position of the joints.
- Underactive or absent reflexes in the knee or ankle.
- Muscle cramping and wasting of the muscles may be present.
- Foot drop is a very late presentation of beriberi but often there is medical intervention before it reaches this stage.
Symptoms of Wet Beriberi
- Rapid heart rate
- Low blood pressure (hypotension)
- Distended neck veins
- Chest pain
- Difficulty breathing, worse when lying flat.
- Swelling of the legs
- Heart failure
Causes of Beriberi
Thiamine deficiency occurs because of :
- low thiamine in the diet
- difficulty or inability to absorb thiamine from the gut
- overuse of thiamine
- loss of thiamine from the body
The human body has a pool of about 30mg of thiamine and it takes about a month to exhaust these stores after ceasing thiamine intake.
Low thiamine intake
In developed nations, low dietary thiamine is uncommon unless a person is starving as is sometimes the case with strict fasting and extreme weight loss diets. Since many foods are fortified with thiamine, even the poor in developed countries do not usually experience this deficiency. Other factors that are more likely to contribute to lower than normal thiamine intake is a result of consuming foods that hamper thiamine absorption or destroy thiamine.
Chronic alcoholism is another major factor for beriberi associated with low thiamine intake and may also lead to other nutritional deficiencies as well. Gastric bypass surgery is another factor, although uncommon. In both chronic alcoholism and gastric bypass surgery the deficiency arises as a result of eating less food and impaired absorption.
Impaired thiamine absorption
Thiamins is primarily absorbed in the small intestine. Therefore various intestinal disease can contribute to thiamine deficiency by impairing the absorption in the gut. This includes various chronic intestinal diseases due to celiac sprue, tropical sprue and alcoholism. With malnutrition, the gut’s ability to absorb nutrients also becomes impaired over time. The disruption in digestion with gastric bypass surgery can also hamper the processing of foods and subsequent thiamine absorption. Genetic beriberi is an inherited condition where the gut’s ability to absorb thiamine is affected.
Overuse of thiamine
Thiamine may sometimes be consumed much faster or in much larger amounts. Normal dietary intake of thiamine may therefore be insufficient to meet the increased demands. It may be due to physiological states like during pregnancy and breastfeeding. Lifestyle factors like extreme physical activity and excessive saturated fat intake or carbohydrate-rich diets may also lead to thiamine deficiency. Pathological states leading to increased utilization of thiamine includes hyperthyroidism (overactive thyroid) and fever due to a severe infection.
Loss of thiamine
Thiamine can be lost through the stool, vomitus, blood or urine. Severe and/or prolonged diarrhea or profuse vomiting leads to thiamine loss through the gut. Pregnant women are at a greater risk of loss in extreme motion sickness (hyperemesis gravidarum) as well as the increased utilization of thiamine due to the developing fetus. Iatrogenic causes may include the use of certain diuretics (“water pills”) and dialysis (hemodialysis and peritoneal dialysis).
Thiamine and Diabetes
Diagnosis of Beriberi
There are several tests that can be conducted to confirm the diagnosis of beriberi. However, administering thiamine intravenously and noting a good clinical response is often sufficient to reach a diagnosis. Beriberi should be suspected in alcoholics displaying the abovementioned symptom but there are various other high risk groups like patients with genetic beriberi. There is an array of blood tests that can confirm the diagnosis of beriberi and urine tests may also be conducted to detect the loss of thiamine via the kidneys.
Treatment of Beriberi
Beriberi can be treated with thiamine supplementation. Initially approximately 50mg of thiamine is administered intravenously or intramuscularly. Then patient can be prescribed oral doses of 5mg to 10mg of thiamine on a daily basis until the symptoms of beriberi resolves. At the same time patients need to be made aware of a good diet and encouraged to eat thiamine-rich foods. A registered dietitian should assist a patient with constructing a simple but effective eating plan. Foods that hamper thiamine absorption or destroy the vitamin should be eaten in moderation and does not need to be avoided entirely. Various other therapeutic measures may be undertaken depending on the cause.