Phytosterols
Phytosterols are compounds synthesized in plants, with a structure and function very similar to cholesterol. Cholesterol, of course, is only found in animal products. Phytosterols actually inhibit the absorption of cholesterol in the intestines. Usually when absorption of cholesterol is inhibited, your body will compensate by making more cholesterol, but if there are phytosterols present this process is also inhibited. As a result, consuming phytosterols can lower your serum cholesterol levels. This has been demonstrated by many studies and is pretty well accepted in the scientific community.
Nature always seems to do things on a grand scale, and it's the same with phytosterols - there are many varieties. Sitosterol and campesterol are found most abundantly in the foods we eat.
In lab tests, sitosterol can induce apoptosis in cancer cells. This is the death signal that tells a cancer cell to shut itself down. There have also been several epidemiological studies where phytosterols are associated with a lowered cancer risk. These are studies in the general population, but it's hard to sort out whether the phytosterols are responsible for the protection against cancer, or whether it is some other compound in the plant diet. There have been a few studies showing that beta-sitosterol can help with urinary tract symptoms in men who have benign enlarged prostate glands. In fact, herbal remedies for this condition often include phytosterols.
Phytosterols are found in most plant based foods, but the best sources are unrefined oils such as vegetable oils, olive oil and nut oils. Good sources of phytosterols are wheat germ, sesame oil, canola and corn oil, peanuts, almonds, brussel sprouts, olive oil and coconuts. Many foods enriched with phytosterols are available in the US, UK, Australia, Europe, New Zealand and some Asian countries. Phytosterols are added to a wide variety of foods like margarines and spreads, mayonnaise, oils, salad dressing, chocolate, milk, soy milk, juices, yogurt and snacks. Studies have found that the most effective enrichment for lowering cholesterol levels is in foods containing fats and a certain amount of moisture, such as milk, yogurt, fat-containing spreads, salad dressings and mayonnaise.
No one can argue that a diet with lots of plant based foods is healthy, but is it safe to eat foods enriched with phytosterols? In the US, phytosterols are on the GRAS list, or foods "generally recognized as safe". But then again, so are a handful of food dyes that are strongly suspected of causing behavioural problems in children. Studies have shown no adverse effects on people who used phytosterol enriched spreads for one year. Some people did experience GI problems such as diarrhea or constipation. This is not a really long time to study the effects of a chemical. One group of people who should NOT use these products are those with a rare hereditary condition called phytosterolemia (also known as sitosterolemia). In this condition the absorbtion of phytosterols is increased in the intestine, causing dramatically high serum levels of the chemicals, which can cause atherosclerosis. Also, it's not known what effect high levels of phytosterols can have on pregnant and lactating women, so they should stay away from enriched products.
If you have high serum cholesterol and are having trouble keeping it under control, talk to your doctor about whether it is safe for you to use products enriched with phytosterols. Otherwise, you can get the benefit of this phytonutrient by eating a wide variety of plant based foods like vegetables, nuts, seeds, legumes, and oils from plants. Remember, cholesterol comes from meats, and phytosterols come from plants.
The information on this page is not meant to be used in treatment of medical conditions. Please seek the advice of a physician about any medical condition or symptom. Those with medical conditions should consult a medical professional about the appropriateness of taking dietary supplements or diet therapy, and how these methods will interact with their medications.
Phytochemical Society of North America
Phytochemical Society of Europe
For detailed information about the chemical structure, formula, and molecular weight of various phytonutrients, visit
The US Dept of Agriculture.
Phytochemicals also gives detailed information on specific phytochemicals.
Search for herbs at the Sloan Kettering Memorial Cancer Center website.