Expert Q&A

Vitamin A: How much is too much?

When should I worry about taking too much Vitamin A?

The risk of taking too much vitamin A mostly depends on the form in which you ingest it. While beta-carotene is less biologically active than vitamin A (retinol), it also has fewer risks than vitamin A. Only a third of the beta carotene ingested is absorbed by the body, whereas 90% of the retinol is absorbed. 

Toxicity symptoms from vitamin A in retinol form are most common in children and include fatigue, irritability, vomiting, and drowsiness. Adults will complain of bone pain, dry scaly skin, headaches, brittle nails, hair loss, gingivitis, and visual disturbances. These symptoms usually occur at high doses (more than 200,000 IU/day) for greater than 6 months. The risks with beta carotene include a yellow discoloration of the skin and depletion of other fat soluble vitamins. Vitamin E should be taken in addition to beta carotene. 

Vitamin A enhances immunity, treats and prevents cancer, treats acne, enhances wound healing, heals skin rashes, and resolves follicular hyperkeratosis (bumps on the back of the upper arms). The recommended dose of vitamin A depends upon the condition being treated. Optimal daily intake with food and supplementation is about 15,000 IU. 

Most people can use vitamin A safely for short periods of time. However, vitamin A can cause birth defects if taken early in pregnancy, and women who are pregnant or who could become pregnant (because they are not using effective birth control methods) should avoid the retinol form of vitamin A.

For more information on taking vitamins during pregnancy see the following article from TheDietChannel: Prenatal Vitamins: Why Preganant Women Should Take Them?

Wendy Hodsdon, ND
Contributing Expert

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