Non-esterified plant sterols solubilized in low fat milks inhibit cholesterol absorption--a stable isotope double-blind crossover study

Summary. Background: The cholesterol absorption inhibiting properties of plant sterols in milks are unknown. The milk fat globule membrane components may enhance the absorption of cholesterol and could make plant sterols less efficient in this complex matrix. Aim of the study: To evaluate in hypercholesterolemic men the cholesterol absorption inhibiting properties of verified properly solubilized, non-esterified plant sterols in partly vegetable oil containing milks. Methods: The plant sterols in milk were determined to be properly solubilized, and to have effective in vitro functionality. Sixteen hypercholesterolemic adult men (initial total cholesterol 5.8–8.6 mM) then consumed milk containing sterols (1.8 g of non-esterified pure plant sterols/d) and control milk, alternatively, during two 6-day periods in a double blind cross over design. During the trial, cholesterol absorption was evaluated from the ratio of plasma isotopic enrichment of 26, 26, 26, 27, 27, 27–²H₆]cholesterol from oral intake (35.6 ± 0.2 μmol, ± SEM) over enrichment of 23, 24, 25, 26, 27–¹³C₅]cholesterol from intravenous injection (77.9 ± 0.5 μmol). Results: Plant sterols in low fat milks contained very few crystals > 11 μm in the presence and absence of bile salts and lysophospholipids, and inhibited cholesterol uptake in Caco-2 cell. This assured that the sterols were properly solubilized prior to the clinical trial. In the clinical study, compliance of volunteers was excellent. After tracer injections (72 h), the plasma ²H] and ¹³C] isotopic enrichments changed from 0.024 ± 0.001 and 0.072 ± 0.003 MPE (control) to 0.015 ± 0.001 and 0.074 ± 0.002 MPE during sterol treatment, respectively. Cholesterol absorption was reduced from 70.1 ± 4.2 % with control to 41.1 ± 4.0 % with milks containing plant sterol (P < 0.001). Conclusions: These results demonstrate that properly solubilized non-esterified plant sterols in milks significantly inhibit cholesterol absorption in mildly hypercholesterolemic men. Received: 10 October 2002, Accepted: 8 January 2003 Correspondence to: Etienne B. Pouteau