Vitamin Deficiency Diseases

Thiamine (B1)

Thiamine converts to a coenzyme in its active form, catalyzing the conversion of amino acids and the metabolism of carbohydrates. Primary food sources of thiamine include pork, beans, and other legumes, nuts, beef, and whole grains. Deficiency is primarily a result of poor dietary intake; however, in developed countries, thiamine deficiency more often results from chronic illness (e.g., cancer) or alcoholism.

A person in the early stages of thiamine deficiency will show symptoms of irritability and poor food intake. The full manifestation of thiamine deficiency is known as beriberi, and is characterized by muscle weakness and wasting, an enlarged heart (cardiomyopathy), pain in the legs and hands (peripheral neuropathy), weakness of one or more eye muscles (opthalmoplegia) and possible swelling of the extremities (edema). If the deficiency arises as a result of chronic alcoholism, the person may also experience central nervous dysfunction that may include loss of balance and psychosis.

The diagnosis of thiamine deficiency is confirmed by functional enzymatic assay. Treatment consists of intravenous or oral thiamine supplementation.

Riboflavin (B2)

Riboflavin is essential as a contributing factor in carbohydrate, fat, and protein metabolism. The most important sources of this vitamin are dairy products and whole grains. Other foods containing riboflavin include broccoli, legumes, eggs, fish, and other meats. Deficiency usually results from lack of dietary intake, and those who follow particularly strict diets (e.g., vegetarians and vegans) are at particular risk if they do not ensure adequate intake of vegetable sources of riboflavin.

The clinical manifestations of riboflavin deficiency include red or purple coloration of the tongue, cracking of the skin around the corners of the mouth, and dandruff. Additional indications of deficiency may include anemia, irritability, or other personality changes.

The diagnosis of riboflavin deficiency can be confirmed with laboratory testing of the blood or urine. Lab diagnostic tools are commonly used, because the clinical symptoms are nonspecific and similar to other vitamin deficiencies. Riboflavin deficiency is treated with supplementation of riboflavin.

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