Nutrition and Health Sciences, Department of


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A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science Major: Nutrition Under the Supervision of Professor Timothy P. Carr Lincoln, Nebraska May, 2010 Copyright 2010 Mark Ash


Naturally occurring compounds and lifestyle modifications as combination and mono-therapy are increasingly used for dyslipidemia. Specficially, phytosterols and fatty acids have demonstrated an ability to modulate cholesterol and triglyceride metabolism in different fashions. In two separate studies, the lipid-lowering effects of black raspberry seed oil and three different phytosterol stearates were examined in order to elucidate the effects of these dietary components and the factors influencing their therapeutic actions.

The first study examined high cholesterol diets supplemented with crude and refined black raspberry seed oils, coconut oil or soybean oil. The crude and refined raspberry seed oil (RSO) treatments significantly altered lipid metabolism, lowering plasma and liver triglycerides while increasing cholesterol ester liver accumulation. Despite the typical reduction of phytosterol content in oils upon processing, both the composition and metabolic effects of the oils did not differ with the exception of increase bile acid excretion in the refined oil.

The second study investigated three phytosterol stearates varying in their phytosterol composition: sitosterol, stigmasterol, or sitostanol. All diets were high in cholesterol and fat to induce dyslipidemia. The phytosterol stearate treatments did not significantly lower plasma cholesterol levels; however, free cholesterol concentrations in the liver were beneficially reduced by both the stanol stearate and sitosterol stearate dietary treatments. Fecal neutral sterol excretion was elevated in the stanol stearate and sitosterol stearate groups versus the cornstarch control, an effect absent in the stigmasterol stearate treatment, indicating that sitosterol stearate may be more effective than stigmasterol stearate at inducing neutral sterol loss via fecal excretion during this study at a 2.5% (g/g) dose.

In summary, both studies demonstrated beneficial but conservative impacts upon cholesterol metabolism by the specified treatments, indicating that RSOs may be a beneficial therapy and that phytosterol stearates do not dramatically differ in their effects upon cholesterol metabolism at a 2.5% dose.