Cryptoxanthin is a garnet-red carotenoid pigment with vitamin A activity that occurs naturally in egg yolks, butter, blood serum and many plants. It is slightly soluble in ethanol and methanol, and soluble in chloroform and benzene. Also known as provitamin A, it can be converted to retinol in the human body, giving it nutritional as well as colouring importance. Food scientists measure it when assessing the nutritional value and colour quality of eggs, dairy products and plant foods, and its levels in animal products respond directly to the carotenoid content of feeds.