Phytosterol esters are
phytosterols derived from
vegetable oils following esterification to
fatty acids. When
phytosterols are added to foods, they inhibit the absorption of dietary and endogenous
cholesterol and thereby reduce blood
cholesterol concentrations. As part of a comprehensive programme of safety assessment, the mutagenic potential of
phytosterols and
phytosterol esters has been assessed in a bacterial mutation assay and an in vitro
chromosome aberration assay. In addition, an in vitro mammalian cell gene mutation assay and two in vivo mutagenicity studies, namely rat bone marrow micronucleus and liver unscheduled
DNA synthesis (UDS) assays, were conducted on
phytosterol esters only.
Phytosterols and
phytosterol esters did not show any evidence of mutagenic activity in any of these assays. A breakdown product of
cholesterol is
4-cholesten-3-one and thus the amount of
4-cholesten-3-one in the gut may increase following supplementation of foods with
phytosterol-
esters.
4-cholesten-3-one had been previously reported as mutagenic but, due to various shortcomings, these data could not be used to assess the mutagenic activity of
4-cholesten-3-one. The mutagenic activity of
4-cholesten-3-one and its major faecal by-products,
5beta-cholestan-3-one, was assessed in two in vitro assays, a bacterial mutation assay and an in vitro
chromosome aberration assay. Neither
4-cholesten-3-one nor
5beta-cholestan-3-one showed evidence of mutagenic activity in these assays.