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National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands
Department of Human Biology, Maastricht University, 6229 ER Maastricht, The Netherlands
* To whom correspondence should be addressed. Email: heidi.fransen{at}rivm.nl.
Dear Editor,
Dr. Jones considered risks of plant sterol consumption and concluded that ingestion of phytosterols is "not potentially hazardous." In our opinion, results from cross-sectional and prospective studies suggest that there is an association between increased plant sterol levels and coronary heart disease (CHD) risk (1–4). We do, however, agree that there are no data supporting a view that the consumption of sterol-enriched products increases the risk for CHD. We explain our views below.
Together with studies in sitosterolemic patients that present atherosclerosis in the absence of hypercholesterolemia, results from observational studies initiated discussion about a potential atherogenic effect of plant sterols (1–4). The findings suggested that plant sterol concentrations are an independent risk marker for CHD; however, these observational studies are not comparable and the results are not conclusive (5). Because consumption of plant sterol–enriched products has been found to increase plant sterol levels in humans, we think it is important to keep this potential negative effect in mind.
Our plasma data showed an increase in plant sterol concentration in consumers of plant sterol–enriched margarines (6). As Dr. Jones stated, the reduction in cholesterol concentration exceeds the increase in plant sterol concentrations, resulting in a net positive effect. Chan et al. (7) also stated that the benefits of plant sterols appear to outweigh the risks. Our goal was not to investigate the effect of increased plasma plant sterol levels on CHD, nor to perform a risk assessment or a complete risk-benefit analysis on plant sterols, but to investigate the changes in plant sterol and plant stanol concentrations after (long-term) consumption of plant sterol- or stanol-enriched margarine, in a free-living population in a nonexperimental setting. We confirmed that elevations of plasma plant sterol concentrations seen in controlled trials also occur in a free-living population over a 5-y follow-up period (6). Whether these increased plant sterol levels could contribute to an increased risk of CHD and, subsequently, partly counteract the established beneficial effects of lowering serum total cholesterol concentrations needs to be investigated in future studies (e.g., long-term trials or epidemiological studies of sufficient size and with firm endpoints). We think further research is needed on plasma plant sterol levels and CHD before solid conclusions can be reached, as is also stated by Chan (7). As such, it remains to be established whether this "potential hazard" is or is not an actual risk, as in a standard risk-characterization paradigm (8). Subsequently, this information could also be used in future risk-benefit analysis.
In conclusion, we agree that there are no data supporting a view that the consumption of sterol-enriched products increases the risk for CHD, but we emphasize the importance of further research into their potential atherogenic effect, the conversion of such potential hazard into a risk, and, finally, a balanced risk-benefit assessment.
Manuscript received 5 September 2007.
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LITERATURE CITED |
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 TOP LITERATURE CITED |
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1. Assmann G, Cullen P, Erbey J, Ramey DR, Kannenberg F, Schulte H. Plasma sitosterol elevations are associated with an increased incidence of coronary events in men: results of a nested case-control analysis of the Prospective Cardiovascular Munster (PROCAM) study. Nutr Metab Cardiovasc Dis. 2006;16:13–21.[Medline]
2. Miettinen TA, Strandberg TE, Gylling H. Noncholesterol sterols and cholesterol lowering by long-term simvastatin treatment in coronary patients: relation to basal serum cholestanol. Arterioscler Thromb Vasc Biol. 2000;20:1340–6.
3. Sutherland WHF, Williams MJA, Nye ER, Restieaux NJ, de Jong SA, Walker HL. Associations of plasma noncholesterol sterol levels with severity of coronary artery disease. Nutr Metab Cardiovasc Dis. 1998;6:386–91.
4. Sudhop T, Gottwald BM, von Bergmann K. Serum plant sterols as a potential risk factor for coronary heart disease. Metabolism. 2002;51:1519–21.[Medline]
5. Patel MD, Thompson PD. Phytosterols and vascular disease. Atherosclerosis. 2006;186:12–9.[Medline]
6. Fransen HP, de Jong N, Wolfs M, Verhagen H, Verschuren WM, Lutjohann D, von Bergmann K, Plat J, Mensink RP. Customary use of plant sterol and plant stanol enriched margarine is associated with changes in serum plant sterol and stanol concentrations in humans. J Nutr. 2007;137:1301–6.
7. Chan YM, Varady KA, Lin Y, Trautwein E, Mensink RP, Plat J, Jones PJ. Plasma concentrations of plant sterols: physiology and relationship with coronary heart disease. Nutr Rev. 2006;64:385–402.[Medline]
8. Renwick AG, Barlow SM, Hertz-Picciotto I, Boobis AR, Dybing E, Edler L, Eisenbrand G, Greig JB, Kleiner J, et al. Risk characterisation of chemicals in food and diet. Food Chem Toxicol. 2003;41:1211–71.[Medline]
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