Ascorbic Acid Supplementation: Influence of Delivery Method on Vitamin C Bioavailability and Capacity to Protect Against Ischemia‐Reperfusion Injury

Intravenous administration of vitamin C has been shown to decrease oxidative stress and, in some instances, improve physiological function in adult humans. Oral vitamin C administration is typically less effective, due in part to decreased vitamin C bioavailability. The purpose of this study was to determine the efficacy of oral delivery of vitamin C encapsulated in liposomes. On 4 separate occasions, occurring in random order, 11 obese adults (age: 53 ± 2 years; body mass index: 34.1 ± 1.0 kg/m 2 (mean ± SE)) were administered an oral placebo, or 4 g of vitamin C via: oral, oral liposomal, or intravenous delivery. The area under the plasma vitamin C concentration curve, determined over 4 hours, was greatest ( P < 0.001) following intravenous administration (57.0 ± 6.9 (mg/dL)·h). Liposomal vitamin C delivery (10.3 ± 0.9) evoked a greater ( P = 0.002) area under the curve than oral (7.6 ± 0.4) that in turn was greater ( P < 0.001) than placebo (3.1 ± 0.4). Forearm ischemia‐reperfusion (20 minutes of occlusion) increased circulating thiobarbituric acid reactive substances, a marker of oxidative stress, 40 minutes post‐reperfusion ( P < 0.03); this increase was prevented by all of the vitamin C treatments ( P > 0.05). These data suggest that oral delivery of vitamin C encapsulated in liposomes: 1) produces circulating concentrations of vitamin C that are greater than traditional oral administration; and, 2) provides protection from ischemia‐reperfusion that is similar to the protection provided by intravenous administration. Support: Empirical Labs