retinotaurine are excreted in the bile, and this retinol conjugate is thought to be an excretory form, as it has little biological activity. Red yeast rice ("cholestin") – significantly reduces toxic effects in rats. Vitamin K prevents hypoprothrombinemia in rats and can sometimes control the increase in plasma/cell ratios of vitamin A. See also Vitamin poisoning Far Eastern Party Retinoic acid syndrome Piblokto References External links Facts about Vitamin A and Carotenoids, from the National Institutes of Health's Office of Dietary Supplements. Effects of external causes Hypervitaminosis