Correlation Between Plasma Vitamin C Concentration and COVID-19 Outcomes among Patients Seen at a Major Hospital in the United Arab Emirates.

Background and objective: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a newly emerged coronavirus that causes coronavirus disease-2019 (COVID-19) with varying degrees of disease manifestations. Vitamin C is an essential water-soluble vitamin with anti-inflammatory, antioxidant, antiviral, and immunomodulatory functions. The study aimed to investigate the association between serum vitamin C concentration and outcomes of COVID-19 among adults in the United Arab Emirates (UAE).

Methods: This retrospective observational study included 67 COVID-19 patients aged 30-59 years old. Measurement of vitamin C levels was performed at the National Reference Laboratory, UAE using liquid chromatography-tandem mass spectrometry (LC/MS-MS). The cut-off value was 0.4 mg/dl; plasma levels that ranged from 0.4 to 2 mg/dl were defined as sufficient. Values above 2 mg/dl were recognized as high and values less than 0.4 mg/dl are considered low or deficient.

Results: Among the included patients, 58.2% suffered from vitamin C deficiency. We found a statistically significant correlation between the concentration of serum vitamin C and age (p=0.03), the presence of hypertension (p=0.013), diabetes (p=0.01), and the development of pneumonia (p=0.012). There was no significant correlation between the concentration of serum vitamin C and the need for mechanical ventilation, Intensive Care Unit (ICU) admission, COVID-19 severity, or mortality. The risk of COVID-19 severity decreased in patients with sufficient vitamin C levels by 52% compared to patients with vitamin C deficiency (p=0.177). There was a statistically significant correlation between vitamin C sufficiency and low lactate dehydrogenase, C-reactive protein (CRP), and fibrinogen. However, the odds of vitamin C sufficiency in COVID-19 patients were significantly associated with lowering CRP levels (OR=0.99, 95% CI (0.98-1.00), p=0.024).

Conclusion and global health implications: Low serum vitamin C concentrations were associated with several demographic characteristics of patients, the presence of pneumonia, and inflammation. Furthermore, improving our social determinants, such as how we live, eat, drink, and vitamin C supplementation could positively impact the future health of the individual, community, and population.