Table 1.

Vitamin C status in patients with COVID-19.

Population Location	Method	Findings	Reference
18 patients with ARDS 1 Barcelona, Spain.	Plasma HPLC-PDA 2	17 patients had <8 µM vitamin C 1 patient had 14 µM vitamin C	[23]
21 ICU 3 patients Thornton, Colorado, USA	Serum	Total cohort (n = 21) had 22 µM vitamin C (45% were deficient, 70% were hypovitaminosis C) Survivors (n = 11) had 29 µM vitamin C Non-Survivors (n = 10) had 15 µM vitamin C	[22]
31 hospitalised patients 51 healthy controlsShanghai, China	Plasma UHPLC-MS 4	6 patients (no IVC 5) had 11 µM vitamin C 25 patients given 100 mg/kg/day IVC had 76 µM 51 healthy controls had 52 µM vitamin C	[21]
50 symptomatic patients 21 healthy controls Jigwa, Nigeria	Serum Colourimetric	Patients had 19 µM vitamin C Controls had 25 µM vitamin C	[25]
9 ICU patients with severe pneumonia Liège, Belgium		Patients had 22 µM vitamin C (reference range: 35–86 µM)	[26]
67 patients with ARDS Barcelona, Spain	Plasma HPLC	Mean vitamin C concentration was 8 ± 3 µM 55 patients (82%) had values <23 µM 12 patients (18%) had values <6 µM	[24]

¹ ARDS: acute respiratory distress syndrome, ² PDA: photo diode array, ³ ICU: intensive care unit, ⁴ UHPLC-MS: ultra-high-performance liquid chromatography-mass spectrometry, ⁵ IVC: intravenous vitamin C. Note: vitamin C concentrations <11 µM are considered deficient, and <23 µM are considered hypovitaminosis C.