# Bioavailability of Liposomal Vitamin C in Powder Form: A Randomized, Double-Blind, Cross-Over Trial
## 3 Results and Discussion
### Clinical Trial Results
#### 3.3.2 Results of Analysis of Pharmacokine Properties of the Tested Formulations  
Figure 5B highlights the changes in the average plasma concentrations of vitamin C within 24 h of administration of the dietary supplements tested. The most important primary parameter compared in this study was the total absorbed dose of the active ingredient, defined as the area under the curve (AUC). For the liposomal vitamin C powder, the AUC value was 445 \(\pm\) 97 mg\(\cdot\)h/L and was statistically significantly higher (\(p\) = 0.0131) than the value obtained for non-liposomal ascorbic acid (AUC = 342 \(\pm\) 45 mg\(\cdot\)h/L) (Figure 5C). The mean of differences for AUC was 6170 (95% CI, 1691 to 10,650; dz =1.22), indicating that the liposomal formulation was superior to the reference formulation with respect to this parameter. The value of the second primary parameter, i.e., the maximum vitamin C concentration achieved in plasma (C\({}_{\text{max}}\)), was numerically but not statistically higher for the liposomal form (28.0 \(\pm\) 6.5 mg/L) than for its non-liposomal counterpart (22.5 \(\pm\) 3.4 mg/L) (\(p\) = 0.0573) (Figure 5D). For the liposomal formulation, the C\({}_{\text{24h}}\) value was 15.85 \(\pm\) 3.26 mg/L and was statistically significantly higher (\(p\) = 0.0199) than the concentration obtained for the non-encapsulated ascorbic acid (12.18 \(\pm\) 2.07 mg/L) (Figure 5F). Moreover, the concentration of vitamin C reached in the blood 10 h after administration of both forms of vitamin C (C\({}_{\text{10h}}\)) (a parameter not subject to analysis planned in the clinical trial protocol) was also statistically significantly higher (\(p\) = 0.004) for the liposomal formulation (17.8 \(\pm\) 4.2 mg/L). For non-liposomal ascorbic acid, C\({}_{\text{10h}}\) was 12.7 \(\pm\) 2.1 mg/L (Figure 5E). The mean of differences for C\({}_{\text{10h}}\) and C\({}_{\text{24h}}\) was 5.1 (95%CI, 2.24-8.1; dz = 1.38) and 3.67 (95% CI, 0.75-6.58; dz = 1.28), respectively. These results demonstrate that the liposomal formulation surpassed the reference formulation in each of the aforementioned parameters. There was no statistical difference (\(p\) = 0.4468) between the T\({}_{\text{max}}\) values obtained for the liposomal (2.56 \(\pm\) 0.53 h) and non-liposomal forms of ascorbic acid (2.33 \(\pm\) 0.70 h). This study shows that compared to non-liposomal vitamin C, oral administration of liposomal vitamin C powder to healthy volunteers resulted in a significantly better absorption of ascorbic acid into the bloodstream, which equated to its higher bioavailability (30% increase in AUC, \(p\) < 0.05). The duration of elevated vitamin C blood levels was also longer (C\({}_{\text{24h}}\) increase of 30%, \(p\) < 0.05), which can reflect a prolonged effect of supplementation. There are studies indicating that liposomal vitamin C has higher bioavailability compared to the non-liposomal form, as reflected in higher AUC values, C\({}_{\text{max}}\), and T\({}_{\text{max}}\). A clinical bioavailability study using an identical 1000 mg dose of liposomal vitamin C but in liquid form was conducted by [PERSON] and [PERSON] [31]. In this case, the liquid suspension of liposomes containing vitamin C had a 1.77 times higher bioavailability (55.86 mg\(\cdot\)h/dL compared to 31.53 mg\(\cdot\)h/dL) and was absorbed 2.41 times faster than its conventional counterpart. In our study, we demonstrated that the AUC for liposomal vitamin C powder was 1.3 times higher. Similarly, [PERSON] et al. [29] reported a 1.35-fold increase in bioavailability (10.3 \(\pm\) 0.9 mg\(\cdot\)h/L compared to 7.6 \(\pm\) 0.4 mg\(\cdot\)h/L) but when 4.25 g of sodium ascorbate (equivalent to 4 g of vitamin C) was administered in liposomal form. In another study, supplementation with 10 g of liposomal vitamin C was shown to enhance ascorbate bioavailability by 1.79 times, with a C\({}_{\text{max}}\) that was 1.67 times higher (300 uM compared to 180 uM) for the liposomal form than for the equivalent dose of the non-liposomal form [30].