From the Guidelines
Vitamin A overdose should be treated by immediately discontinuing all vitamin A supplements and seeking medical attention, as there is no recognized treatment for toxicity other than stopping supplementation 1. Vitamin A overdose, also known as hypervitaminosis A, occurs when excessive amounts of vitamin A accumulate in the body. This condition can develop from taking high-dose supplements over time or, rarely, from consuming extremely large amounts at once. Symptoms of vitamin A toxicity include:
- Nausea
- Headache
- Dizziness
- Blurred vision
- Skin irritation
- Joint and bone pain
- In severe cases, liver damage According to the espen micronutrient guideline, acute toxicity develops when quantities of natural vitamin A above 300,000 IU (adults) or > 60,000 IU (children) are ingested within a few hours or days 1. Chronic toxicity results from the ingestion of daily amounts of >25,000 IU for more than 6 years or >100,000 IU for more than 6 months, with a high inter-individual variability 1. The recommended daily allowance for vitamin A is below the upper limit of 3,000 mcg per day, set by the IOM for women of childbearing age 1. Vitamin A toxicity occurs because it's fat-soluble, meaning excess amounts aren't excreted but instead stored in the body's fat tissues and liver. Pregnant women should be especially cautious with vitamin A supplements as excessive amounts can cause birth defects. Most people can get adequate vitamin A through a balanced diet including foods like carrots, sweet potatoes, spinach, and liver without needing supplements.
From the Research
Vitamin A Overdose Symptoms
- Hypercalcemia, hepatomegaly, and dermatological and neurological effects are common symptoms of vitamin A toxicity, as described in 2
- Osteoporosis and hip fracture are associated with preformed vitamin A intakes that are only twice the current RDA, according to 3
Vitamin A Toxicity Effects
- The acute and chronic effects of vitamin A toxicity are well documented in the literature, including liver injury ranging from acute hepatitis to cirrhosis, as mentioned in 3 and 4
- Subtoxicity without clinical signs of toxicity may be a growing concern, especially in developed countries, as suggested by 3
Treatment and Prevention
- Assessing vitamin A status in persons with subtoxicity or toxicity is complicated, and further research is needed to evaluate the effects of subclinical toxicity on overall health and well-being, as stated in 3
- Vitamin A supplementation can alleviate extrahepatic cholestasis liver injury through Nrf2 activation, as found in 5
- Steroids, such as prednisolone, can be used as rescue therapy for vitamin A-induced acute liver failure, as reported in 4
Diagnosis and Interpretation
- Abnormal liver biochemical tests can be categorized based on the pattern and magnitude of aminotransferases elevation, and vitamin A-induced liver injury can be classified as a hepatocellular pattern, as discussed in 6
- Accurate interpretation of liver biochemical tests is crucial for appropriate further workup, treatment, and referral, as emphasized in 6