(June 2016)
Plant sterols (phytosterols, phytostanols and their fatty acid esters) are cholesterol-like substances that occur naturally at low levels in fruits, vegetables, nuts and cereals.

When eaten at the recommended amount, between 2 and 3 grams a day, plant sterols can reduce low-density lipoprotein (LDL) cholesterol levels in our blood (based on recommendation of Food Standards Australia New Zealand.) Most people obtain between 150 and 360 milligrams of plant sterols daily, depending on diet.

This ingredient reduces absorption of cholesterol in the small intestines and lowers LDL, the “bad” cholesterol in blood.  The European Food Safety Authority suggested daily intake of 1.5-2.4g of phytosterol,8  which is unlikely to be fulfilled eating a normal diet.  Hong Kong University Studies demonstrated a reduction of 7-10% in LDL cholesterol by taking 1.5-2.4g phytosterol daily for 2 to 3 weeks.  Long term intake of phytosterol has a sustained effect on the LDL cholesterol level, especially in conjunction with a low fat diet and sufficient exercise.  Every reduction of 0.6mmol/L cholesterol is associated with approximately 50% reduction in the risk of coronary heart disease.9

References
http://www.foodstandards.gov.au/consumer/nutrition/plantsterol/Pages/default.aspx
http://www.elderly.gov.hk/english/newsletter/vol45/p2.html
https://www.hku.hk/press/news_detail_13642.html