Plant Sterols and Cholesterol
Plant sterols are the plant version of cholesterol. Plant cell membranes contain plant sterols, and animal cell membranes contain cholesterol. We produce cholesterol in the liver and consume some in animal-based foods. Plant sterols are naturally present in plant foods, are structurally similar to cholesterol, and serve similar functions in plant cell membranes to those of cholesterol in animal cell membranes.
Plant sterols (also known as phytosterols) naturally occur in a range of plant sources such as vegetables, beans, grains, seeds and nuts. The richest whole food sources of plant sterols are pistachio nuts, Mediterranean pine nuts and sunflower seeds; followed by cashews, split peas, kidney beans, almonds and other nuts.
When we consume plant sterols, these substances appear similar to cholesterol to the cells lining the small intestine, which allows them to bind to the sites on those cells that cholesterol would bind to in order to be absorbed. This is one way; plant sterols block the absorption of cholesterol from food and the re-absorption of cholesterol produced by the liver, which lowers cholesterol levels. More than forty human trials have collectively shown that plant sterol supplements can safely reduce LDL levels by up to 15%.1
Plant sterols are one of the many components of a healthful diet based on whole plant foods that keep cholesterol levels in check. For people who have difficulty getting their LDL cholesterol levels into the favorable range, plant sterol supplements are a safe and effective choice.
In addition to lowering cholesterol, plant sterols have also been shown to have anti-cancer, anti-inflammatory, anti-atherogenic and antioxidant activities.2 Observational studies have shown that higher plant sterol intake is associated with a lower risk of cancers of the lung, esophagus, stomach and breast.3-7
Additionally, dietary plant sterols are reported to play a protective therapeutic role in benign prostatic hypertrophy (BPH or enlarged prostate), a common medical condition in older men.8 Clinical symptoms of BPH have been shown to be improved by supplementation of small doses (60-130 mg) of plant sterols. Supplementation was also associated with improvements in prostatic function compared to placebo. 9
1. Weingartner O, Bohm M, Laufs U: Controversial role of plant sterol esters in the management of hypercholesterolaemia. Eur Heart J 2009;30:404-409.
2. Berger A, Jones PJ, Abumweis SS: Plant sterols: factors affecting their efficacy and safety as functional food ingredients. Lipids Health Dis 2004;3:5.
3. Woyengo TA, Ramprasath VR, Jones PJ: Anticancer effects of phytosterols. Eur J Clin Nutr 2009;63:813-820.
4. Mendilaharsu M, De Stefani E, Deneo-Pellegrini H, et al: Phytosterols and risk of lung cancer: a case-control study in Uruguay. Lung Cancer 1998;21:37-45.
5. Ronco A, De Stefani E, Boffetta P, et al: Vegetables, fruits, and related nutrients and risk of breast cancer: a case-control study in Uruguay. Nutr Cancer 1999;35:111-119.
6. De Stefani E, Brennan P, Boffetta P, et al: Vegetables, fruits, related dietary antioxidants, and risk of squamous cell carcinoma of the esophagus: a case-control study in Uruguay. Nutr Cancer 2000;38:23-29.
7. De Stefani E, Boffetta P, Ronco AL, et al: Plant sterols and risk of stomach cancer: a case-control study in Uruguay. Nutr Cancer 2000;37:140-144.
8. Klippel KF, Hiltl DM, Schipp B: A multicentric, placebo-controlled, double-blind clinical trial of beta-sitosterol (phytosterol) for the treatment of benign prostatic hyperplasia. German BPH-Phyto Study group. Br J Urol 1997;80:427-432.
9. Berges RR, Kassen A, Senge T: Treatment of symptomatic benign prostatic hyperplasia with beta-sitosterol: an 18-month follow-up. BJU Int 2000;85:842-846.