Safety evaluation of certain food additives - ipcs inchem

140 PHYTOSTEROLS, PHYTOSTANOLS AND THEIR ESTERS
In a study submitted to the SCF, healthy human volunteers consumed 20 g
fat spread per day containing 8% phytosterols for 1 year. After adjustment for lipid
content, the only significant change consisted of a decrease in -carotene (21%
compared with the baseline at the start of the study). This decrease occurred despite
the fact that the fat spread was supplemented with 50 mg carotenoids/kg fat (mainly
-carotene and lycopene added for coloration) (Scientific Committee on Food,
2000).
In a review, 18 human studies were evaluated for observations regarding
effects of phytosterols and phytostanols on serum levels of (pro)vitamins. After
consumption of 1.5 g/day or more, absolute serum concentrations of -carotene,
-carotene, lycopene and -tocopherol were decreased by 9%, 20%, 7% and 6%,
respectively. Only -carotene remained statistically significantly decreased after
adjustment for change in total serum cholesterol. On average, levels of vitamins D
and A were not different between subjects consuming phytosterols or phytostanols
and controls. Vitamin K–dependent clotting factors were not influenced by
consumption of phytostanols (Katan et al., 2003). Interestingly, a meta-analysis
based on standardized data available in the literature concluded that the decrease
in plasma -carotene levels plateaus when the daily intake of phytosterols and
phytostanols reaches 2.2 g (Plat et al., 2000).
In addition to the beneficial effects on lipid concentrations summarized
above, some of the new placebo-controlled human trials also investigated
potentially harmful effects on (pro)vitamins and other parameters. Effects on
carotenoid and tocopherol levels observed in these studies are summarized in Table
6. Some of the studies in addition investigated possible effects on plasma
concentrations of vitamins D and K. Levels of these vitamins were not influenced
by consumption of phytosterols or phytostanols (Raeini-Sarjaz et al., 2002; Korpela
et al., 2006).
As with the older studies, effects on most (pro)vitamins in the new studies
(see Table 6) diminished when concentrations were lipid adjusted. In a 1-year study,
serum concentrations of -carotene, -carotene, -tocopherol and lycopene were
lower after phytosterol consumption (1.7 g phytosterols/day as esters in fat spread),
compared with controls. -Carotene concentrations after 52 weeks, but not carotene
levels, remained statistically significantly lower in the exposed group,
when expressed per millimole LDL cholesterol, compared with the placebo control.
Also, differential decreases in - and -carotene concentrations per time between
weeks 0 and 52 were significantly lower compared with controls, with or without
adjustment to changes in LDL cholesterol. Within the study period, lipid-adjusted
concentrations of - and -carotene decreased by 4% and 28%, respectively. No
differences in levels of vitamins A, B12 and K1 and folic acid were observed between
persons consuming phytosterol-enriched fat spread and those consuming control
spread (Hendriks et al., 2003). Another study investigated the effect on carotenoid
levels after long-term (1-year) administration of sitostanol esters in margarine to
humans. In this study, absolute plasma levels of -carotene, -carotene and tocopherol
were significantly reduced in 102 individuals with moderate
hypercholesterolaemia after ingestion of sitostanol esters (equivalent to 3.0 g sitostanol/day)
in margarine. After normalization to cholesterol concentration, only
reduction of -carotene (33%) remained statistically significant (Gylling et al., 1999).