No description available.

Whey protein isolates (WPI) have been indicated to have potent cholesterol lowering and antioxidative properties. Such effects, however, are not consistently observed, which could be the result of major differences in the processing, isolation and composition of WPI. Moreover, the mechanisms of action or the bioactive component(s) in WPI are poorly understood although the relatively high cysteine content in WPI has been suggested to play an important role. Although high dietary cysteine has been shown to lower plasma homocysteine concentrations, the impact of WPI in this regard has not been investigated. The overall objective of this thesis was to examine the antioxidative and plasma cholesterol and homocysteine lowering properties of two WPI that were produced via different industrial processing and isolation techniques with the milk protein, casein, used as the control protein. We also examined for the mechanism(s) of action of WPI in terms of possible antioxidative, and plasma cholesterol and homocysteine lowering effects. In this regard, the intake of bovine serum albumin (BSA), a major cysteine-rich whey protein was also studied since this protein has been implicated as a key bioactive component for the antioxidant effects of WPI. Four studies were performed. The first involved the characterization of a variety of commercially prepared WPI by high performance capillary electrophoresis for identification of two WPI products that showed major differences in protein composition for subsequent feeding trials. Most of the WPI had similar characteristic electrophoretic profiles, however, significant differences in protein and macronutrient (Ca, Mg, P) composition were noted in two commercial WPI that were chosen as the test proteins in subsequent feeding trials. In the first two feeding studies, hamsters were fed different commercial WPI or milk protein (BSA or casein) containing diets that were either matched or unmatched in terms of macro

No description available.

The objective of this study was to examine the effects of a medium chain triglyceride oil mixture (MCTo), designed to increase energy expenditure and improve lipid profiles containing medium chain triglycerides, phytosterols and n-3 fatty acids in the form of flaxseed oil, versus the antioxidant alpha-lipoic acid (ALA). Forty-eight hamsters were fed (i) hypercholesterol emic (HC) control, (ii) HC MCTo, (iii) HC ALA, (iv) HC MCTo/ALA diets for 4 weeks. No effects on food intake, body weight, total body water, lean body mass, fat mass, and tissue thiobarbituric acid-reactive substances (TBARS) were observed. ALA alone had no effect on total cholesterol (TC); however, MCTo feeding increased TC with (p < 0.03) and without (p < 0.003) ALA when compared to control. ALA increased HDL levels compared to control (p 0.04) and MCTo/ALA (p < 0.007) groups. MCTo, with (p < 0.0001) or without (p < 0.006) ALA, increased non-HDL cholesterol levels versus control. The non-HDL:HDL ratio was decreased by ALA compared to MCTo (45%) and MCTo/ALA (68%) (p < 0.0001), a similar trend was seen when compared to the HC control (22%) group (p < 0.14). Triglyceride levels were not altered by any of the dietary treatments. Liver and heart tissue reduced glutathione (GSH) was increased (p < 0.05) by all three treatments when compared to control. Both tissues showed an increase (p < 0.05) in oxidized glutathione (GSSG) when fed ALA compared to all other treatments. Hamsters fed ALA had a lower (p < 0.05) GSH/GSSG ratio compared to all treatment groups. In conclusion, MCTo feeding does not elicit beneficial effects on circulating plasma lipids and measures of body composition. In addition, our results do not clearly support an improvement in oxidative status through supplementation of ALA. However, our results do support the existence of beneficial effects of ALA on circulating lipoprotein content in the hamster.

No description available.