Effects of long term plant sterol and -stanol consumption on the retinal vasculature: A randomized controlled trial in statin users

As sitosterolemic patients have an increased cardiovascular risk, there is concern that reducing serum LDL-cholesterol concentrations by plant sterols enriched functional foods might adversely affect vascular function. Whether increased concentrations of plant sterols truly affect vascular function and whether these effects are exclusive to the larger vessels remains unknown. We compared the effects of long-term plant sterol and -stanol consumption on changes in retinal vessels diameter which reflex alterations in the microcirculation. Three randomized groups were studied at baseline and after 85-weeks. Group one (N = 11) consumed plant sterol enriched margarine (2.5 g/day), the second (N = 8) plant stanol enriched margarine (2.5 g/day), and the control group (N = 11) non-enriched margarine (2.5 g/day). Serum cholesterol-standardized campesterol and sitosterol concentrations increased by 354.84 ± 168.22·102 μmol/mmol and 84.36 ± 48.26·102 μmol/mmol (p < 0.001), respectively in the sterol group, while decreasing non-significantly in the plant stanol group. Serum LDL-cholesterol concentrations decreased significantly in both the plant sterol (−0.33 ± 0.33 mmol/L, p = 0.016) and -stanol groups (−0.38 ± 0.34 mmol/L, p = 0.018) compared to the increase in the controls (0.29 ± 0.34 mmol/L). The mean change in venular diameters for the plant sterol group (2.3 ± 3.1 μm), plant stanol groups (−0.8 ± 3.4 μm) and control group (−0.8 ± 5.1 μm) did not reach significance but the change in cholesterol-standardized campesterol concentrations correlated positively with the change in venular diameter independent of changes in serum LDL-cholesterol concentrations (r = 0.39, N = 30, p = 0.033). Increased serum campesterol concentration correlated positively with increased retinal venular diameter, independent from changes in serum LDL-cholesterol concentrations. This may constitute an explanation for the suggested effects of plant sterols on vascular function. However, this novel finding needs confirmation and further study.