To assess the effectiveness (extent to which an intervention works in daily medical practice) of the use of phytosterol/phytostanol-enriched margarines to lower total and non-HDL cholesterol levels in users and non-users of statins.

Retrospective cohort study.

Data were obtained from questionnaires on health and food intake from a population-based longitudinal cohort linked to pharmacy-dispensing records.

The analysis included 3829 men and women (aged 31–71 years) who were examined during 1998–2002 and re-examined at 5-year follow-up during 2003–2007.

Recommended doses of margarines were consumed by only 9 % of the subjects. Serum total cholesterol decreased by respectively −0·16 (95 % CI −0·26, −0·05) mmol/l, −1·40 (95 % CI −1·51, −1·30) mmol/l and −1·64 (95 % CI −1·91, −1·37) mmol/l in subjects who started to use phytosterols/phytostanols only, statins only or a combination of both compounds at some point in time between examination and re-examination, compared with subjects who did not start using phytosterols/phytostanols or statins. Cholesterol-lowering effects of the phytosterols/phytostanols were similar in statin users and statin non-users and increased with increasing intake of enriched margarine (no intake, 0; low intake, −0·017 (95 % CI −0·16, 0·13) mmol/l; medium intake, −0·089 (95 % CI −0·22, 0·038) mmol/l; high intake, −0·32 (95 % CI −0·50, −0·14) mmol/l).

Although recommended intake levels of the enriched margarines were not reached by all persons, these data show that under customary conditions of use phytosterols/phytostanols are effective in lowering cholesterol levels in both statin users and non-users.