Mechanisms of action of plant sterols on inhibition of cholesterol absorption. Comparison of sitosterol and sitostanol.
Level 2 - randomized trial
Randomized clinical perfusion trial
What was done
Normal volunteers underwent an intestinal perfusion study to compare the effects of two plant sterols on cholesterol absorption. Following a baseline control period, subjects were randomized to receive a high-dose intestinal infusion (3.6 µmol/min) of either sitosterol (Group I) or sitostanol (Group II).
What was found
Baseline cholesterol absorption during the control period was similar between groups: 0.88 ± 0.48 µmol/min (32 ± 11%) in the sitosterol group and 0.68 ± 0.33 µmol/min (29 ± 9%) in the sitostanol group. Sitosterol infusion significantly reduced cholesterol absorption to 0.47 µmol/min (16%), representing an overall reduction of almost 50%. Sitostanol infusion reduced cholesterol absorption to 0.15 ± 0.11 µmol/min (5.1 ± 2.9%), representing an overall reduction of almost 85%.
Why it matters
This study provides direct physiological evidence in humans that sitostanol is markedly more effective than sitosterol at inhibiting cholesterol absorption, supporting the mechanism of competitive displacement of cholesterol from mixed micelles due to higher sterol hydrophobicity.
Limits
The abstract does not state the sample size or participant characteristics beyond describing them as normal volunteers. The experimental setup used acute, direct high-dose intestinal infusions rather than chronic oral dietary intake, and long-term lipid outcomes were not measured.
Cited by
- supports High intake of plant sterols (phytosterols) reduces total cholesterol absorption by outcompeting cholesterol at enterocytes in the gut.