In a patient with cholestasis, why might vitamin K absorption be impaired?

Vitamin K absorption can be impaired in patients with cholestasis primarily due to its reliance on micelle formation for effective absorption in the intestine. Vitamin K is a fat-soluble vitamin, which means it requires the presence of bile salts to be incorporated into micelles. Micelles are essential for the intestinal absorption of lipid-soluble substances, as they help to solubilize these compounds in the aqueous environment of the intestinal lumen, facilitating their uptake by enterocytes.

In cholestasis, the flow of bile is decreased or blocked, leading to inadequate bile salts in the intestine. Without sufficient bile salts, micelle formation is compromised, thus impairing the absorption of fat-soluble vitamins, including vitamin K. This can lead to deficiencies, which are particularly problematic as vitamin K is crucial for the synthesis of clotting factors in the liver.

Although activation in the liver is relevant for the biological activity of vitamin K, it is not the direct reason for impaired absorption in the context of cholestasis. Similarly, while specific enzymes play a role in various metabolic processes, they are not the primary factor influencing the absorption of vitamin K in this scenario. Alterations in intestinal pH can affect absorption but are less significant compared to the effect of bile salts and mic