Phytosterols are a family of compounds similar to cholesterol which have been shown to lower cholesterol levels when supplemented in the diet. A daily dose of 2–3 g of phytosterols has been shown to reduce LDL-cholesterol levels by 5–15%. Phytosterol supplementation can be undertaken using phytosterol enriched functional foods or nutraceutical preparations. The type of phytosterol supplemented, such as plant sterol or saturated plant stanol appear to be equally effective in lowering cholesterol levels. Phytosterols, whether in esterified or free form have both been shown to lower cholesterol levels, with esterified phytosterol formulations having a greater number of clinical trials demonstrating efficacy. The functional food or nutraceutical matrix which is used to deliver supplemental phytosterols can significantly affect cholesterol lowering efficacy. Effective cholesterol lowering by phytosterols depends on delivery of phytosterols to the intestine in a form which can compete with cholesterol for absorption. New phytosterol functional food and nutraceuticals products should always be tested to demonstrate adequate delivery of phytosterol dose and effective total and LDL-cholesterol lowering. Phytosterol products which do not effectively lower cholesterol will negatively impact the perception and use of phytosterols, and must not be allowed on the marketplace.