Vitamin B1 (Thiamin)
Thiamin is a water-soluble vitamin that functions as a coenzyme in the conversion of glucose into energy. It is particularly vulnerable to loss during food preparation, as it is easily destroyed by heat, air, and water. Thiamin is found primarily in the germ and bran of grains. It is absorbed rapidly in the upper and lower portions of the small intestine.
The body does not store significant amounts of thiamin, making a regular daily intake necessary. High intake of refined sugar increases the body’s demand for thiamin, and habits such as smoking and alcohol consumption can further deplete thiamin levels.
Thiamin deficiency interferes with carbohydrate metabolism, leading to the accumulation of pyruvic acid in the blood. This buildup can result in reduced mental alertness, labored breathing, and damage to cardiac tissue. Early signs of deficiency include fatigue, loss of appetite, irritability, and emotional instability. With ongoing deficiency, confusion and memory loss may develop.
Beriberi is the disease caused by severe thiamin deficiency. The most advanced neurological changes occur in the peripheral nerves, particularly those supplying the lower extremities. The distal portions of nerves are affected first and most severely. Degeneration of the myelin sheath has been observed in multiple tracts of the spinal cord, especially in the posterior columns and in the anterior and posterior nerve roots. Changes may also be seen in anterior horn cells and posterior root ganglia.
Cardiac involvement includes dilation and enlargement of the heart. Muscle fibers may become swollen, fragmented, and vacuolated, with fluid accumulation in the interstitial spaces. Edema and serous effusions may develop in advanced cases.
Early thiamin deficiency may present with fatigue, irritability, poor memory, sleep disturbances, chest discomfort, loss of appetite, abdominal discomfort, and constipation.
Peripheral neurological signs are typically bilateral and symmetrical, most often affecting the lower extremities. Early symptoms include tingling of the toes, burning sensations in the feet (especially at night), calf muscle cramps, leg pain, reduced vibratory sensation in the toes, and difficulty rising from a squatting position. As the condition progresses, reflexes are lost—first the ankle jerk, then the knee jerk—followed by loss of position and vibratory sense, muscle wasting of the calves and thighs, and eventually foot drop and toe drop. In advanced deficiency, the arms may also become involved after leg symptoms are well established.
