Influence of Chitosan Treatment on Surrogate Serum Markers of Cholesterol Metabolism in Obese Subjects

Dieter Lütjohann (1*), Milka Marinova (2), Karsten Wolter (2), Winfried Willinek (2,3), Norman Bitterlich (4), Martin Coenen (1), Christoph Coch (1) and Frans Stellaard (1)

1 Institute for Clinical Chemistry and Clinical Pharmacology, University Clinics of Bonn, D-53127 Bonn, Germany; martin.coenen@ukb.uni-bonn.de (M.C.); ccoch@uni-bonn.de (C.C.); fstellaard@hotmail.com (F.S.)

2 Department of Radiology, University Clinics of Bonn, D-53127 Bonn, Germany; milka.marinova@ukb.uni-bonn.de (M.M.); karsten.wolter@ukb.uni-bonn.de (K.W.); w.willinek@bk-trier.de (W.W.)

3 Department of Radiology, Neuroradiology, Sonography and Nuclear Medicine, Krankenhaus der Barmherzigen Brüder Trier, D-54292 Trier, Germany

4 Medizin & Service GmbH, Abt. Biostatistik, Boettcherstraße 10, D-09117 Chemnitz, Germany; bitterlich@medizinservice-sachsen.de

* Correspondence: dieter.luetjohann@ukbonn.de; Tel.: +49-228-2871-4027

Abstract: Chitosan treatment results in significantly lower serum low density lipoprotein (LDL) cholesterol concentrations. To assess the working mechanisms of chitosan, we measured serum surrogate markers of cholesterol absorption (campesterol, sitosterol, cholestanol), synthesis (lathosterol, lanosterol, desmosterol), and degradation to bile acids (7α-hydroxy-cholesterol, 27-hydroxy cholesterol), corrected for cholesterol concentration (R_sterols). Over 12 weeks, 116 obese subjects (Body Mass Index, BMI 31.7, range 28.1–38.9 kg/m2) were studied under chitosan (n = 61) and placebo treatments (n = 55). The participants were briefly educated regarding improvement of nutrition quality and energy expenditure. Daily chitosan intake was 3200 mg. Serum LDL cholesterol concentration decreased significantly more (p = 0.0252) under chitosan (−8.67 ± 18.18 mg/dL, 5.6%) than under placebo treatment (−1.00 ± 24.22 mg/dL, 0.9%). This reduction was not associated with the expected greater decreases in markers of cholesterol absorption under chitosan treatment. Also, increases in markers of cholesterol synthesis and bile acid synthesis under chitosan treatment were not any greater than under placebo treatment. In conclusion, a significant selective reduction of serum LDL cholesterol under chitosan treatment is neither associated with a reduction of serum surrogate markers of cholesterol absorption, nor with increases of markers for cholesterol and bile acid synthesis.