Side effects of Vitamin A

Data source: http://www.exrx.net/Nutrition/Antioxidants/VitaminA.html

The use of acne medicines (i.e. Acutane) has led to birth defects and even death (11) in children born to mothers using these compounds (6). This has helped make the public more aware of the toxic properties of vitamin A.

In adults a condition known as hypervitaminosis exhibits itself after chronic ingestion of the vitamin in doses that are ten times the RDA (10 mg RE).

Symptoms of vitamin A toxicity include:

anorexia,

headache,

bone and muscle pain,

vomiting,

alopecia,

liver damage,

and coma.

These symptoms slowly reside as vitamin A intake levels are reduced. To date the only side effect of excess beta-carotene has been yellowing of the skin, most commonly in the fatty areas of the hands and palms. The yellowing disappears as beta-carotene intake decreases. This commonly ingested dietary precursor to vitamin A has yet to exhibit any signs of toxicity even at levels as high as 180 mg per day. Researchers believe that the presentation of unbound retinol to the cell is a major factor in toxicity. Excessive intakes of vitamin A saturate RBP and instead of retinol being transferred bound to RBP, it is transferred to the tissue via plasma lipoproteins. When retinol reaches the tissue by a carrier other than RBP it is hypothesized that the retinol is released and causes toxic side effects.

Side Effects

Data source: http://health.nytimes.com/health/guides/nutrition/vitamin-a/overview.html

If you don't get enough vitamin A, you are more susceptible to infectious diseases and vision problems.

If you get too much vitamin A, you can become sick. Large doses of vitamin A can also cause birth defects. Acute vitamin A poisoning usually occurs when an adult takes several hundred thousand IU.  Symptoms of chronic vitamin A poisoning may occur in adults who regularly take more than 25,000 IU a day. Babies and children are more sensitive and can become sick after taking smaller doses of vitamin A or vitamin A-containing products such as retinol (found in skin creams).

See Hypervitaminosis A.

Increased amounts of beta-carotene can turn the color of skin to yellow or orange. The skin color returns to normal once the increased intake of beta-carotene is reduced.