Supports Healthy Cholesterol Levels already within the normal range With CardioAid-S Plant Sterol Esters Plus added Fish Oil CardioAid-S Plant Sterol Esters is a combination of the ester forms of Beta-Sitosterol, Campesterol and Stigmasterol. Plant Sterols are plant-derived compounds that are structurally similar to cholesterol so that they help to limit the absorption of cholesterol from the digestive tract. In this way, CardioAid-S can help to maintain cholesterol levels already within the normal range.