The vitamin B complex includes not only niacin and thiamin but also riboflavin and other substances. When riboflavin is deficient the symptoms noted include principally fissures and soreness at the corners of the mouth, redness of the white portion, or cornea, of the eye with pain on seeing strong light, and also some changes in the tongue and skin.
Seldom is a deficiency of riboflavin observed alone, since it is so closely associated with other portions of the vitamin B complex. Most of the symptoms are regularly associated with pellagra, which is chiefly the result of lack of niacin.
Dr. William Darby has described the appearances around the corners of the mouth which are typical. First the lips get pale at the comers, then they seem chewed or softened, after which the fissures appear. As these heal, pink scars appear. The sore spots may become covered with crusts. The surface of the tongue gets a mushroom-like appearance and the color has been described as magenta.
Patients with ariboflavinosis complain of a sandy feeling of the eyelids, with blurring of vision and burning on exposure to strong light. As in pellagra these patients have a record of failure to include in their diets such substances as lean meat, green leafy vegetables, milk, eggs or liver.
Once the diet of the patient is supplemented with adequate amounts of the food mentioned, the symptoms disappear. In difficult cases doctors prescribe a normal dosage of riboflavin itself. Since, however, few patients have an uncomplicated shortage of riboflavin, but rather a shortage of all of the vitamin B complex and since B complex is so easy to secure and administer, the whole B complex is given.