Relationships between viscosity of hydroxypropyl methylcellulose and plasma cholesterol in hamsters

Dietary high viscosity hydroxypropyl methylcellulose (HPMC) lowered plasma and liver cholesterol concentrations in cholesterol-fed hamsters. To determine the level of viscosity needed to effect a significant reduction in total plasma cholesterol, hamsters were fed for 3 wk diets containing 0.12% cholesterol and either 4% cellulose or one of four preparations of HPMC that varied in viscosity between 14 and 1698 centipoise (cP), as estimated in vitro. Blood was collected for plasma cholesterol determination, and intestinal contents were obtained by finger-stripping of the excised small intestine. Contents were centrifuged and the supernatant (ex vivo) viscosity determined. In vitro and ex vivo viscosities were correlated (R² = 0.96). Plasma cholesterol concentrations declined as in vitro or ex vivo viscosity increased. Maximal plasma cholesterol reduction occurred at an ex vivo viscosity of ~150 cP. There was a linear relationship between plasma cholesterol and the logarithm of ex vivo viscosity (R² = 0.98). Our results suggest that materials that increase the viscosity of intestinal contents can be effective in reducing plasma cholesterol and that only moderate increases in viscosity are necessary to achieve this effect.