Vitamin A is essential for vision, immunity, reproduction, and normal cell growth.
However, excessive intake of **preformed vitamin A**, such as retinol or retinyl palmitate, can accumulate in the body because vitamin A is fat-soluble.
Very high or prolonged doses can potentially cause:
* liver enzyme abnormalities
* liver injury
* headaches
* nausea
* bone problems
* dry or peeling skin
The risk mainly applies to
high-dose supplements containing preformed vitamin A rather than beta-carotene naturally found in fruits and vegetables.
The NIH Office of Dietary Supplements specifically warns that excessive preformed vitamin A can damage the liver.
### Be especially careful if:
* you take multiple supplements containing vitamin A
* you use high-dose retinol products
* you already have liver disease
* you regularly consume large amounts of alcohol
More vitamin A is not necessarily better.
## 2. Vitamin D
