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The Effects of Excess Riboflavin

Riboflavin, also known as vitamin B2, is a water-soluble vitamin that helps produce energy in all of the body's cells. It is needed for healthy skin, hair, liver, heart, nerves, blood cells, digestive system lining and metabolism of fats, carbohydrates and protein. Since dairy, liver, mushrooms, eggs, green leafy vegetables, beans, fish, enriched bread and grain products contain riboflavin, the American diet usually provides adequate amounts. Because excess amounts are removed through urine, few side effects are known, but testing shows that excessive amounts may cause effects.

  1. Adverse Cellular Effects

    • According to Smart Publication's analysis of nutritional studies, riboflavin has the ability to react with light, resulting in adverse cellular effects. In the article "Excess Vitamin B2 - Riboflavin Can Be Toxic!", Dr. Joseph Pizzorno speculates that exposure to sun and ultraviolet light for individuals with excessive riboflavin intake may cause the problems it usually prevents. The combination of riboflavin and light is used by scientist to induce cataracts, liver dysfunction and mutations in animal studies, and according to Sigma-Aldrich, high levels of riboflavin combined with light can cause build up of toxic hydrogen peroxides and a riboflavin-tryptophan photo adduct that damages the liver and cells. According to Oregon State University's Linus Pauling Institute, studies in cell culture indicate that excess riboflavin may increase the risk of DNA strand breaks when chromium, which is a carcinogenic, is present.

    Test Result Effects

    • According to Drugs.com, certain drugs, such as alcohol, probenecid and antidepressants can interact with excess riboflavin that is normally absorbed by the intestines and excreted from the body. During diagnostic tests, riboflavin may produce fluorescent substances that falsely elevate results or produce false-positive results for blood tests or urinalysis.

    Urine Discoloration

    • The most obvious, universal effect of excess riboflavin is urine discoloration. Large doses of riboflavin may cause a bright orange-yellow discoloration of urine. Oregon State University Linus Pauling Institute claims this is a harmless side effect and that the color returns to normal as excess riboflavin is removed from the system, but according to Natural Reliefs, the discoloration could affect urine analysis results.

    Excess Riboflavin Reactions

    • According to the Health Supplements Nutritional Guide, toxicity is rarely seen even in high levels of riboflavin. Both the nutritional guide and Natural Reliefs list possible reactions to excessive overdosing that include such skin reactions as itching, numbness, sensations of burning or prickling and sensitivity to sunlight. According to Natural Reliefs, high doses of riboflavin can reduce the effectiveness of the anticancer drug methotrexate.

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