# Bioavailability of Liposomal Vitamin C in Powder Form: A Randomized, Double-Blind, Cross-Over Trial
###### Abstract  
The purpose of this study was to evaluate the properties and pharmacokinetics of liposomal vitamin C in powder form obtained by a method devoid of organic solvents. The powder and liposome morphology were analyzed using scanning electron microscopy (SEM) and cryogenic transmission electron microscopy (cryo-TEM), respectively. Additionally, the carrier particle size, size distribution (STEP-Technology)2; L.U.M. GmbH, Berlin, Germany), and zeta potential value were determined. The pharmacokinetic parameters of liposomal and non-liposomal vitamin C (AUC, C\({}_{\text{max}}\), C\({}_{\text{1 fb}}\), and C\({}_{\text{2 dh}}\)) were compared in a randomized, single-dose, double-blind, cross-over trial (ClinicalTrials.gov ID: NCT05843617) involving healthy adult volunteers (n = 10, 1000 mg dose). The process of spray drying used to transform liquid suspensions of the liposomes into powder form did not adversely affect the quality of the carrier particles obtained. Compared to non-encapsulated vitamin C, oral administration of the liposomal formulation resulted in significantly better absorption of ascorbic acid into the bloodstream, which equated to a higher bioavailability of the liposomal product (30% increase in AUC, \(p<0.05\)). The duration of elevated vitamin C blood levels was also longer (C\({}_{\text{2 dh}}\) increase of 30%, \(p<0.05\)). Although the results obtained are promising and suggest higher bioavailability for the liposomal form of vitamin C, the limited sample size necessitates further research with a larger cohort to confirm these findings. 2024 14 7718  
enzyme L-gulonolactone oxidase (GLO, EC 1.1.3.8) in their bodies [3]. Hence, they need to derive vitamin C from their food [1; 2; 3; 4]. The daily requirement for vitamin C varies according to age, gender, physiological state (pregnancy and lactation in women), and lifestyle [2]. Nevertheless, the recommended daily intake of the vitamin may also differ depending on the expert institution formulating the recommendations. Those given by the Health and Medicine Division (formerly known as the Institute of Medicine, IoM), EFSA, and FAO/WHO range from 15 to 50 mg/day for infants and children up to three years of age, and from 25 to 90-100 mg/day for older children and adolescents. For adult men, they are 45-110 mg/day, and for adult women, 45-95 mg/day. The recommended intake of vitamin C increases by a further 10 mg/day and 25-60 mg/day for pregnant and lactating adult women, respectively [5; 6; 7]. Increasing the intake of the vitamin by a further 35-40 mg/day is also sometimes recommended for habitual smokers [5; 8]. Although the main dietary sources of vitamin C are fruits and vegetables [4], their consumption does not always guarantee an adequate supply of this active substance. The ascorbic acid content of plant materials fluctuates [1] depending largely on their type. For instance, in the case of fresh fruits, it can vary from 3.2 mg/100 g of grapes to 181.0 mg/100 g of blackcurrants, and for fresh vegetables, from 9.2 mg/100 g of lettuce (green leaf) to 133.0 mg/100 g of parsley [9]. The vitamin C content of fruits and vegetables is also impacted by the duration of transportation to the point of sale [1], the storage period and conditions, and the thermal processing parameters of the raw and/or semi-finished product [1; 4; 10]. The supply of vitamin C in food ratios is also negatively affected by modern lifestyles, including the increased consumption of energy-dense, low-nutrient foods [11] and the more frequent consumption of meals--usually low in vegetables--when eating out or consuming take-away meals [12; 13]. For seniors, especially women (\(\geq\)65 years old), the average intake of vitamin C also decreases with age [14]. Therefore, vitamin C is increasingly being added to foods, beverages, and premixes [4; 15; 16]. The results of published studies indicate that it is also one of the most commonly supplemented micronutrients [17; 18; 19; 20].