Riboflavin deficiency is caused by a dietary lack of vitamin B 2.It occurs when the chronic (long-term) failure to eat sufficient amounts of foods that contain riboflavin produces skin lesions, lesions of smooth surfaces in the digestive tract, or nervous disorders.
Riboflavin, also called vitamin B2, is a water-soluble vitamin. The recommended daily allowance (RDA) is 1.7 mg/day for an adult man and 1.3 mg/day for an adult woman. The best sources of this vitamin are meat, dairy products, and dark green vegetables, especially broccoli. Grains and legumes (beans and peas) also contribute riboflavin to the diet. Riboflavin is requiredfor the processing of dietary fats, carbohydrates, and proteins to convert these nutrients to energy. It is also used for the continual process of renewaland regeneration of all cells and tissues in the body.
Riboflavin is sensitive to light. For this reason, commercially available milk is sometimes supplied in cartons rather than in clear bottles. Milk contains about 1.7 mg riboflavin/kg, cheese contains about 4.3 mg/kg, beef has 2.4 mg/kg, and broccoli has about 2.0 mg/kg. Riboflavin is not rapidly destroyed by cooking.
A deficiency in riboflavin alone has never occurred in the natural environment. Although poorer populations in the United States have a higher rate of riboflavin deficiency, the affected individuals are also deficient in a number of other nutrients, as well. In contrast, diseases where people are deficientin one vitamin only--such as thiamin, vitamin C, or vitamin D, for example--have been clearly documented. When riboflavin deficiency is actually detected,it is often associated with low consumption of milk, chronic alcoholism, orchronic diarrhea.
The symptoms of riboflavin deficiency include:
- Swelling and fissuring(breaking or cracking) of the lips (cheilosis)
- Ulceration and cracking of the angles of the mouth (angular stomatitis)
- Oily, scaly skin rashes on the scrotum, vulva, or area between the nose and lips
- Inflammation of the tongue
- Red, itchy eyes that are sensitive to light.
The nervous symptoms of riboflavin deficiency include:
- Numbness of thehands
- Decreased sensitivity to touch, temperature, and vibration.
Riboflavin status is diagnosed using a test conducted on red blood cells thatmeasures the activity of an enzyme called glutathione reductase. An extractof the red blood cells is placed in two test tubes. One test tube contains noadded riboflavin, while the second test tube contains a derivative of riboflavin, called flavin adenine dinucleotide. The added riboflavin derivative results in little or no stimulation of enzyme activity in patients with normal riboflavin levels. A stimulation of 20% or less is considered normal. A stimulation of more than 20% means the patient is deficient in riboflavin.
Riboflavin deficiency can be treated with supplemental riboflavin (0.5 mg/kgbody weight per day) until the symptoms disappear. The prognosis (expected cure rate) for riboflavin deficiency is excellent, and it can be prevented by including milk, cheese, yogurt, meat, and/or certain vegetables in the daily diet. Of the vegetables, broccoli, asparagus, and spinach are highest in riboflavin, having a content ratio similar to that of milk, yogurt, or meat.