Sterols of plants are called phytosterols and sterols of animals are called zoosterols. The most important zoosterol is cholesterol; notable phytosterols include campesterol, sitosterol, and stigmasterol.
Ergosterol is a sterol present in the cell membrane of fungi, where it serves a role similar to cholesterol in animal cells. Sterols and related compounds play essential roles in the physiology of eukaryotic organisms.
For example, cholesterol forms part of the cellular membrane in animals, where it affects the cell membrane’s fluidity and serves as a secondary messenger in developmental signaling.
In humans and other animals, corticosteroids, such as cortisol act as signaling compounds in cellular communication and general metabolism. Sterols are common components of human skin oils.
Plant sterols differ from sterols of other origins in their diversity. In the plant kingdom, about 250 sterols have been reported and as many as 60 sterols have been detected from a single plant.1,2 Many of these compounds comprise intermediates in the various biosynthetic pathways to Δ5-sterols.
Plant sterols are a group of plant substances that resemble cholesterol. They might help reduce cholesterol levels by limiting the amount of cholesterol that is able to enter the body. Some plant sterols might also reduce how much cholesterol is made in the body. Plant sterols are LIKELY SAFE for most people when taken by mouth. They can cause some side effects, such as diarrhea or fat in the stool.
Plant sterol esters or plant stanol esters have been added to some margarines and spreads because of their cholesterol-lowering effect. Several studies have indicated that consumption of about 2 grams per day provides a reduction in LDL cholesterol of about 10%. (Katan & et al., 2003) (IFIC, July 2007)