Plant sterols, also known as phytosterols, are natural compounds found in various plant-based foods. They have garnered interest for their health implications.
Understanding Plant Sterols
Plant sterols are compounds structurally similar to cholesterol, found in animal cells. Over 250 types of phytosterols exist, with beta-sitosterol, campesterol, and stigmasterol being common. In plants, these compounds maintain cell membrane fluidity and permeability, much like cholesterol in animals. They also contribute to plant growth and development, acting as precursors to plant hormones called brassinosteroids. Plant sterols influence how plants respond to environmental challenges like temperature extremes, drought, and pathogens.
Sources of Plant Sterols
Plant sterols are naturally present in many everyday foods. Unrefined plant oils, such as vegetable, nut, and olive oils, contain high concentrations of these compounds. Other natural sources include nuts, seeds, whole grains like rice bran and wheat germ, and legumes such as dried peas, beans, and lentils. Fruits and vegetables, including oranges, apples, avocados, broccoli, and Brussels sprouts, also contribute to plant sterol intake.
Beyond naturally occurring sources, plant sterols are frequently added to certain foods to enhance their nutritional profile. These fortified foods often include margarines, yogurts, milks, and orange juices. The amount of plant sterols in these fortified products can vary, so checking food labels is helpful to determine the specific content per serving.
How Plant Sterols Support Health
The primary way plant sterols support health is by interfering with the absorption of cholesterol in the digestive tract. Due to their similar structure to cholesterol, plant sterols compete with cholesterol for incorporation into mixed micelles, which are necessary for cholesterol absorption in the intestines. This competition reduces the amount of dietary cholesterol that can be absorbed by the body.
Consequently, less cholesterol enters the bloodstream, leading to lower levels of low-density lipoprotein (LDL) cholesterol, often referred to as “bad” cholesterol. While the body may slightly increase its own cholesterol production in response to reduced absorption, this increase is generally not enough to fully compensate for the lower absorption from the diet. The absorbed plant sterols are efficiently excreted from the liver, maintaining low circulating levels in the body.
Adding Plant Sterols to Your Diet
To effectively incorporate plant sterols for their health benefits, a daily intake of approximately 2 grams is often recommended for cholesterol-lowering effects. This amount has been shown to reduce LDL cholesterol levels by about 5% to 15% over a few weeks. It is generally advised to consume plant sterols with meals or snacks throughout the day, as this helps them mix with food and optimize their cholesterol-lowering action.
While natural food sources contribute to plant sterol intake, the typical Western diet provides only about 200 to 400 milligrams per day, which is generally insufficient to achieve significant cholesterol reduction. Therefore, fortified foods or supplements are often needed to reach the recommended 2-gram daily target. For instance, two teaspoons of fortified spread, one fortified yogurt, or one glass (250 ml) of fortified milk can each provide around 0.8 grams of plant sterols.