Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions.
Level 2 - randomized trial
Scoping review of mixed randomized and non-randomized pharmacokinetic trials without pooled meta-analysis
PubMed 40506693 · doi:10.1111/bcpt.70067
What was done
A scoping review searched databases and manual records to identify studies comparing the pharmacokinetic bioavailability of liposomal versus non-liposomal ascorbate (vitamin C). From 321 identified records, 10 studies were included: seven randomized crossover trials, one parallel-group trial, and two non-randomized studies. Study protocols evaluated ascorbate doses ranging from 0.15 g to 10 g and post-dose sample collection windows between 4 and 24 hours.
What was found
Nine of the 10 studies reported higher bioavailability for liposomal compared to non-liposomal ascorbate, with increases of 1.2- to 5.4-fold in peak concentration (Cmax) and 1.3- to 7.2-fold in area under the curve (AUC). None of the 10 studies measured urinary ascorbate elimination. Only two studies evaluated in vivo cellular uptake, and only two evaluated potential biological effects.
Why it matters
Liposomal delivery appears to enhance plasma vitamin C concentrations compared to standard formulations across various doses. However, the lack of elimination and tissue uptake data means higher circulating levels cannot yet be equated with superior physiological retention or biological efficacy.
Limits
Substantial heterogeneity in liposomal formulation types, doses (0.15-10 g), and pharmacokinetic sampling durations (4-24 h) prevented direct cross-study comparisons. Two of the 10 studies were non-randomized, overall participant sample sizes were not reported in the abstract, and baseline vitamin C status was not factored into study designs.
Cited by
- supports In a study of 20 people, a single 10-gram dose of liposomal vitamin C increased plasma levels to 300 micromoles per liter, took an hour longer to reach peak concentration, and had a half-life two hours longer than non-encapsulated vitamin C.