retinol
2 interactions related to retinol
vitamin d3 + vitamin a
Vitamin D and vitamin A act through partnered nuclear receptors. Vitamin D's active form binds the vitamin D receptor (VDR), which pairs with the retinoid X receptor (RXR) — whose ligand comes from vitamin A — to switch on genes for immunity, epithelial health, and bone. Adequate levels of both support this signaling, but at extreme doses they can work against each other for calcium and bone endpoints, where a controlled human study showed high preformed vitamin A blunting vitamin D's calcium response.
alcohol + vitamin a
Alcohol depletes the liver's vitamin A by inducing cytochrome P450 enzymes (notably CYP2E1) that break retinol down into toxic byproducts. Adding high-dose vitamin A or beta-carotene supplements on top of regular drinking can worsen liver injury rather than correct the deficiency, so repletion in drinkers is not as simple as taking a pill.