Plant sterols and plant stanols are collectively known as phytosterols. Plant sterols are plant compounds with chemical structures similar to that of cholesterol. Especially high sterol levels are found in rice bran, wheat germ, corn oils, and soybeans. In a more concentrated form, these substances are called plant stanols. Structurally these compounds are chemically similar to cholesterol. However, unlike cholesterol derived from animal sources--which absorbs easily and raises the body's own cholesterol levels--phytosterols are present only at very low levels in the body because they are difficult to absorb.
Interestingly, phytosterols so closely resemble cholesterol that they can actually block food-based cholesterol from being absorbed into the bloodstream. The result is that both phytosterols and dietary cholesterol end up excreted in waste matter.
Recently food manufacturers have begun to incorporate plant sterols and stanols into such "functional foods" as vegetable oil spreads (Benecol or Take Control, for example). Nutritional supplement manufacturers also offer phytosterols in tablet form for those individuals who don't want the extra calories of cholesterol-lowering margarine.
Concentrated extracts of another phytosterol called beta sistosterol have been tested for lessening such discomforts of benign prostatic hyperplasia (BPH) as frequent and painful urination (see the library entry on beta-sistosterol for more detailed information).
Health Benefits
Because of their ability to block dietary cholesterol absorption, phytosterols can help lower your cholesterol levels. In the last few years, clinical research has also discovered other effects, including reducing symptoms of an enlarged prostate, improving the control of blood sugar among people with diabetes, and reducing inflammation among patients with autoimmune diseases such as rheumatoid arthritis and lupus.
Because much of this research is still in a preliminary phase, nutritionally oriented physicians are currently recommending phytosterols only for prostate disorders and cholesterol-lowering.
Specifically, phytosterols may help to:
Prevent heart disease. By lowering total and LDL cholesterol levels, plant sterols and stanols may reduce your risk of heart disease. Studies have shown that daily phytosterols can lower these cholesterol measurements by an average of 10% to 14%. Because of these strong findings, the National Cholesterol Education Panel issued a new recommendation in 2001 that plant stanols and sterols be added to cholesterol-lowering regimens, along with the more traditional cholesterol-fighting tools, such as regular exercise, weight loss, and a low-fat diet. Phytosterols do not appear to lower triglycerides, another blood lipid that is harmful in excess, or to raise levels of HDL, the "good" cholesterol.
Ease enlarged prostate. For the last 20 years, an herbal preparation containing phytosterols has been available in Germany for treatment of benign prostate hypertrophy (BPH). More recently, two six-month studies on 350 men with BPH given the phytosterol beta-sitosterol showed an increase in their urinary flow rate and a decrease in pain and burning.
Calm inflammation in rheumatoid arthritis (RA). Most traditional treatments for RA involve drugs that suppress the body's immune response, which can often cause troubling side effects. A mixture of the phytosterols beta-sitosterol and beta-sistosterolin has shown promise in helping to decrease inflammation and calm the overactive immune response that characterizes RA and other autoimmune diseases. More research is needed, however.
Control blood sugar in diabetes. Some phytosterols stimulate insulin secretion and may contribute to better blood sugar control, a problem in people with diabetes. Animal studies have suggested that beta-sitosterol and beta-sistosterolin might be beneficial for people with diabetic and pre-diabetic conditions. More research is necessary before these findings are recommended to people with diabetes.
Dosage Information
Special tips:
--The cholesterol-controlling margarines such as Benecol and Take Control suggest a dose of 2 tablespoons daily to help lower total and LDL cholesterol levels.
For lowering cholesterol: Take 200-250 mg three times a day, with meals.
For enlarged prostate (BPH): Take 125-250 mg a day, on an empty stomach.
[Guidelines for Use]
Because phytosterols help block dietary cholesterol adsorption, they should be taken with meals.
Beta-sitosterol, when used for prostate enlargement, is generally taken on an empty stomach to enhance its absorption into the bloodstream.
Some research has shown that phytosterols can slightly lower concentrations of fat-soluble vitamins such as beta-carotene, but other studies show no such effect. Although carotene levels normally vary with the seasons, it may be a reasonable precaution to increase your intake of beta-carotene (or carotene-containing foods such as carrots, yellow squash, and sweet potatoes) while taking phytosterol supplements.
If you are taking phytosterols in the margarine form, simply replace your usual spread. You may need to eat somewhat larger amounts than you are accustomed to in order to achieve an effective dose.
Be sure to check out our Dosage Recommendations Chart which lists therapeutic dosages for specific ailments at a glance.
General Interaction
There are no known drug or nutrient interactions associated with phytosterols in typical doses. There may be some reduction in the body's levels of carotenoids, but this finding is under debate.
Possible Side Effects
At typical doses, there are no known side effects or adverse reactions. However, in one study in which participants took three to four times the suggested dose, some gastrointestinal upset occurred.
Cautions
There are no known cautions associated with plant sterols.
Ailments Dosage
High Cholesterol Take 200-250 mg three times a day, with meals.
Prostate Problems Take 125-250 mg a day.