Vitamin A Overdosage
Article Highlights
- Vitamin A overdosage may develop from a single large dose or prolonged intake of moderate doses of vitamin A.
- Overdosage may be toxic to the brain, liver, skin and many other organ systems.
- Overdosage with beta-carotene is not dangerous but will turn your skin yellow!
It is easy to get too much vitamin A, especially if also taking supplemental vitamin A by itself or in a multivitamin. A single vitamin A dose of 300,000 IU or intake of 50,000 IU per day for prolonged periods may result in toxicity in a healthy adult. Ingestion of 20,000 IU or more per day for a month or more may result in toxity in healthy infants and children. Normal vitamin A plasma levels are between 30 and 70 mcg/dl. For individuals who receive sufficient vitamin A in their diet and desire a multivitamin free of vitamin A, ebA (everything but “A”) Multivitamin Supplement is available.
Acute vitamin A toxicity includes symptoms that mimic a brain tumor (pseudotumor cerebri) including headaches, irritability, drowsiness, fatigue, blurred vision, papilledema and vomiting. Other signs include swelling of the optic nerve (papilledema), swelling of the arms and legs (peripheral edema) and, 24 hours after taking a single toxic dose, widespread skin peeling. In infants, acute toxicity may manifest as bulging fontanels and vomiting.
Chronic vitamin A toxicity may mimic a brain tumor as well but also may include liver and spleen enlargement or liver cirrhosis leading to yellowing of the skin (jaundice) and whites of the eyes (icterus), and fluid in the abdomen (ascites). Other signs and symptoms include lymph node enlargement, sleep difficulty, bone, joint and/or muscle pains, constipation, dry itchy or peeling skin, dry mucous membranes, fissuring of the lips, gingivitis, hypomenorrhea, and hair loss.
Excessive ingestion of carotenoids causes yellow discoloration of the skin (hypercarotonemia), especially of the palms and soles, which is reversible. This is not to be confused with jaundice, is not dangerous, and can be distinguished from jaundice by the absence of yellowing of the whites of the eyes. Individuals with diabetes or hypothyroidism may not convert beta-carotene to vitamin A as efficiently and may develop hypercarotonemia more readily.