20a-Hydroxycholesterol is primarily used in research settings to study its role in biological processes, particularly in the context of cholesterol metabolism and steroidogenesis. It serves as a key intermediate in the biosynthesis of steroid hormones, making it valuable for investigating pathways involved in hormone production. Researchers also utilize it to explore its potential effects on cell signaling and membrane fluidity, as well as its interactions with nuclear receptors like LXR (liver X receptor), which are involved in lipid homeostasis. Additionally, it is employed in studies related to immune regulation and inflammation, as it may influence immune cell function. Its applications are largely confined to laboratory studies aimed at understanding its physiological and biochemical significance.