The users of plant stanol ester margarine are a self-selected group of persons who have taken an active interest in their health. They use plant stanol ester margarine as part of a generally healthy life-style and diet. Nevertheless, they commonly have a history of cardiovascular disease or are at risk to have it. Thus plant stanol ester margarine seems to be used by persons for whom it was designed and in a way it was meant: as part of efforts for cardiovascular disease risk reduction.
Users of plant stanol ester margarine appear in this early post-marketing adoption phase to be elderly people. They reported generally good or average health status and took more commonly cholesterol-lowering drugs as compared with nonusers. Overall, users with cardiovascular disease seemed to share similar characteristics compared with users without cardiovascular disease, although users with cardiovascular disease tended to be slightly older.
As the plant stanol ester margarine has been recommended in Finland for the primary and secondary prevention of coronary heart disease , we assume that the users with cardiovascular disease attempt to control elevated cholesterol levels and prevent the progress of the disease. Users of plant stanol ester margarine who do not have cardiovascular disease probably also aim to control cholesterol levels and thus prevent cardiovascular disease. Unfortunately, we were unable to directly evaluate this issue, since data on indication for use of plant stanol ester margarine was not collected.
However, the plant stanol ester margarine users both with and without cardiovascular disease obviously had more cholesterol problems than nonusers as they reported more of elevated blood cholesterol and dietary counseling for lowering of blood cholesterol. Furthermore, as the price of the plant stanol ester margarine is 3–5 times higher than other margarines, its use is likely based on clearly perceived need, i.e. the control of blood cholesterol levels.
The use of plant stanol ester margarine may also result from "practical reasons": if one spouse uses it, the other may be more likely to use it too. Previous studies show spouse concordance for physiological and behavioral indicators such as plasma cholesterol and triglyceride, blood pressure, diet, body mass index, smoking and physical exercise [14–17]. The similarity in the characteristics of plant stanol ester margarine users with and without cardiovascular disease might well be explained by family reasons.
Our information on the use of plant stanol ester margarine was based on a single question concerning the type of bread spread usually used. Although we have not validated the question against real use, we assume that the question reliably measures current use and that conclusions can be drawn concerning the characteristics of the users. Information concerning the quantity of the plant stanol ester margarine use was obtained from the Finrisk survey and was shown to be 20 g per day, on an average. A picture from a portion size picture booklet describing the amount of spread on bread was used to improve the validity of the estimation . The quantity should be 20–25 g per day to achieve an optimal cholesterol-lowering effect [6, 7], but it is clear from our data that higher levels of use are common.
The age and geographic distributions of the study cohort of 42 406 persons differ slightly from the general Finnish population. The proportion of persons aged 55–64 years is greater (24% versus 20%) and 65–84 years smaller (19% versus 24%) than in the general population. The proportion of persons living in eastern Finland is greater (20% versus 11%) and southern Finland smaller (30% versus 40%) compared with the general population. As the proportion of users is high among less represented groups, i.e. persons aged 65–74 years and those living in southern and thus urban areas of Finland, our cohort probably underestimates the frequency of the use of plant stanol ester margarine in the Finnish population.
Functional foods are usually carefully examined with respect to their health effects and safety before they come to market. These studies often have limitations such as short length of follow-up. Also effects in certain population or patient subgroups might be unknown due to small sample size. Therefore there is a need for post-marketing surveillance. Until now only few post-marketing studies concerning functional foods have been carried out namely with a food additive sweetener aspartame  and a non-energy fat substitute olestra  as the most notable exceptions.
The LDL-cholesterol reducing effect of plant sterols and stanols may result in reduced heart disease rates. However, they appear to somewhat lower lipid-standardized concentrations of the plasma carotenoids [2, 5]. Also the health effects of high daily amounts of plant sterols and stanols are unknown. In our future follow-up studies, we will evaluate possible health effects, both beneficial and adverse, of the long-term use of the plant stanol ester margarine by linking available Finnish health outcome registries to the study cohort .