Davis, Janelle Lynn, authorBell, Christopher, advisorHamilton, Karyn, committee memberFrye, Melinda, committee member2015-08-272016-06-032015http://hdl.handle.net/10217/166978Intravenous delivery of vitamin C to adult humans decreases indices of oxidative stress and in some instances improves physiological function. Oral delivery of vitamin C is more practical than intravenous but typically results in lower circulating vitamin C concentrations. The hypotheses for this study were, oral consumption of vitamin C encapsulated in liposomes would: 1) result in higher circulating vitamin C concentrations than a traditional oral supplement, and 2) better attenuate oxidative stress induced by ischemia-reperfusion. Eleven overweight/obese adults [age: 52±7 years; body mass index: 34.1±1.0 kg/m²; mean±SE] were administered a 4 g supplement of placebo, or vitamin C via different delivery methods, on four separate occasions, in a random order. The four treatments were: placebo, oral vitamin C, liposomal vitamin C, and intravenous (IV) administration of vitamin C. Concentrations of ascorbic acid, thiobarbituric acid reactive substances (TBARS), and oxidized low-density lipoproteins (Ox-LDL) were measured in venous blood at baseline, and over four hours following supplement administration. At three hours a blood pressure cuff was placed around the upper arm and inflated to 200 mmHg for 20 minutes to evoke an ischemia-reperfusion injury. Plasma ascorbic acid concentrations were significantly greater after IV vitamin C compared with all other treatments at all time points (P<0.01). At two hours, all subsequent ascorbic acid concentrations were greater after liposomal vitamin C treatment compared with oral vitamin C and placebo treatments. Plasma ascorbic acid concentrations were greater after oral vitamin C compared with placebo (P<0.01). Neither vitamin C nor ischemia-reperfusion influenced Ox-LDL. In the placebo condition, ischemia-reperfusion increased plasma TBARS concentration; all of the vitamin C treatments prevented this increase. These data suggest that liposomal encapsulation of vitamin C increases bioavailability of oral vitamin C. Additionally, the antioxidant protection provided by liposomal vitamin C is not inferior to intravenously administered vitamin C.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text