What it does
Preformed vitamin A is found in animal foods, while provitamin A carotenoids occur in colorful plant foods and can be converted by the body. These forms differ in potency and risk at high intake.
Food sources and absorption
Liver, dairy, eggs, and fortified foods provide preformed vitamin A. Sweet potatoes, carrots, squash, spinach, kale, and other orange or dark-green produce provide carotenoids.
Safety and individual context
Excess preformed vitamin A from supplements or frequent liver intake can be harmful, particularly during pregnancy. Beta-carotene supplements are not equivalent to eating carotenoid-rich vegetables and have specific risks for smokers.
Primary reference
NIH Office of Dietary Supplements consumer fact sheet
How to use this information
Reference values describe population needs and are not a diagnosis. Food patterns, health conditions, pregnancy, laboratory results, and medications can change what is appropriate. Avoid high-dose supplementation unless there is a clear reason and qualified guidance.