I'm no expert but from the link you provided, I believe what happens is this. You eat something that when broken down by digestion has cholesterol in it. Normally, the cholesterol would be absorbed into the blood stream through the intestines. When saponins are present, they stick with the bile the body uses to digest fats. They use cholesterol as the "glue" to bind with the bile. If the cholesterol is busy working as glue it cannot be absorbed into the bloodstream.
I hope this helps.