The key step in cholesterol synthesis is the formation of mevalonate from beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA), which is catalyzed by HMG-CoA reductas

The key step in cholesterol synthesis is the formation of mevalonate from beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA), which is catalyzed by HMG-CoA reductase. You can be certain that that HMG-CoA reductase is really, really important in cholesterol biosynthesis because statins work by blocking this enzyme. HMG-CoA reductase activity is induced by insulin, and reduced by glucagon. To really control cholesterol, it's more important to cut carbs, not dietary sources of cholesterol (which fall anyway when appetite control is restored as leptin receptors in the hypothalamus regain function.)