"Blood cholesterol levels remained stable over a period of five years in users of phytosterol and -stanol enriched margarines whereas it increased in non-users," wrote lead author Marion Wolfs.
"Although this effect seems to be modest, it can still reduce the risk of coronary heart disease and thereby result in health benefits in the general population."
Numerous clinical trials in controlled settings have reported that daily consumption of 1.5 to 3 grams of phytosterols/-stanols can reduce total cholesterol levels by eight to 17 per cent, representing a significant reduction in the risk of cardiovascular disease, but whether such benefits are repeated by everyday people in everyday life is not known, said the Dutch researchers.
"Until now the effects of phytosterol/-stanol enriched foods have only been studied with controlled intake of phytosterols or -stanols," explained Wolfs, from the Dutch National Institute for Public Health and the Environment.
"To our knowledge, no study has been published in which the effect of foods enriched with phytosterols/-stanols on blood lipids has been investigated under free-living conditions without a controlled diet."
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.
The new study, published in the journal Food and Chemical Toxicology (Vol. 44, pp. 1682-1688), used data from the Dutch Doetinchem cohort study. Over 4500 subjects were examined initially between 1994 and1998 and then again five years later (1999 to 2003). Seventy-two people were found to be regular enriched margarine users.
Dietary intake was assessed using validated food frequency questionnaires, and participants were asked to quantify use of the bread-spreads Becel pro-activ (phytosterol-enriched) and Benecol (phytostanol-enriched). These were the main sources of these substances on the Dutch market up to 2003, said the researchers.
It was found that men used significantly more enriched margarine than women, and that the average daily consumption of the phytosterol/-stanol margarines was 15 and 9 grams, respectively.
The ratio of total cholesterol to HDL cholesterol, reported to be the most specific lipid risk factor for CVD, decreased for the users by 0.29 millimoles per litre after five years. This ratio increased slightly for non-users by 0.26 millimoles per litre of serum.
However, only 26 per cent of the users achieved the 10 per cent reductions in total blood cholesterol concentrations that are "claimed by the producers of the phytosterol/-stanol enriched margarines," reported Wolfs.
The overall net effect in this free-living population, said Wolfs, is less than most clinical trials, and is a stabilisation of cholesterol levels, rather than the slight increase observed naturally with age.
Even though the effects are modest this can still translate into cardiovascular disease risk reduction, said the researchers.
"To our knowledge, this study is the first to present achieved effects of customary phytosterol and -stanol enriched margarine use. As such this confirms to the extensive database on efficacy of these in controlled clinical trials," concluded Wolfs.
The researchers called for extension of this post-launch monitoring method to other functional foods and functional food ingredients as an important way of analysing consumption patterns, as well as for notification, analysis and evaluation of possible averse effects.
The study has been welcomed by Ingmar Wester, vice president regulatory and scientific affairs at Raisio and inventor of the Benecol ingredient, who told NutraIngredients.com that it clearly confirmed the beneficial effects on serum cholesterol of phytosterol/-stanol-enriched margarine-type spreads, even though the recorded intake was surprisingly lower than the recommended.
"The recorded mean spontaneous daily intake of spreads with added sterols (15g) or stanols (9g) are far from the recommended (which was 25 g Benecol spread/day) for optimal cholesterol reduction. The estimated recorded daily intake of sterols and stanols was 1.2g and 0.7g respectively, which is lower than recommended daily intake of about 2 g," said Wester.
Yet, this lower than recommended daily intake appears to show that the concern raised by certain EU Member States regarding over consumption of phytosterols/-stanols seemed unfounded, said Wester.
"The fact that more subjects amongst users were diagnosed with high cholesterol and that the mean serum cholesterol levels of users was significantly higher than that of the non-users shows that the products efficiently have found the target group, indicating that the marketing messages have been appropriate."