Phytosterols and related derivatives phytostanols are naturally occurring
bioactive compounds present mainly in plant cell membranes. These lipophilic steroid
alcohols contain a tetracyclic cyclopenta [a] phenanthrene structure which is
substituted with a hydroxyl group at position C3 and have a side chain at position C17,
usually containing one or more double bonds in the steroid skeleton. Phytosterols
derived from isopentenyl pyrophosphate belong to the terpene family and are generally
synthesized by the mevalonate pathway. They have similar structural and biological
functions to cholesterol. It is not possible to synthesize by a human; as a result of their
intake in diet, they are present in the human body as cereals, legumes, vegetables,
fruits, nuts, vegetable oils, oilseeds, cereal grains, cereal-based products and related
products which contain phytosterols in relatively high amount, consumed daily by the
whole world population. Phytosterols are known as part of the normal human diet.
Increasing interest has been given to phytosterols in recent years as epidemiological
and experimental studies suggest that they have an important role in the protection
from cancer besides their several beneficial effects, such as anti-inflammatory,
antioxidative, anticarcinogenic, antifungal, antibacterial, antipyretic, antineoplastic,
anti-ulcerative activity and cholesterol-lowering capacity. Inhibition tumor cell growth,
multiplication, invasion and metastasis; reducing cell proliferation and increasing
apoptosis; decreasing tumor size; inhibition of carcinogen production; reduction of
angiogenesis and adhesion of cancer cells; inhibition of reactive oxygen species
production and oxidative stress and increased antioxidant enzymes have been
suggested as responsible mechanisms for anticancer activity of phytosterols. The
current review aims to summarize the occurrence, safety, toxicity and chemistry of
phytosterols to explain their potential activities in cancer with suggested mechanisms in
detail. Furthermore, epidemiological and experimental studies related to treating the
activity of phytosterols in gastrointestinal system cancers have been described.
Keywords: Gastric cancer, Molecular mechanisms, Phytonutrients, Phytosterols, β-sitosterol.
