Vitamin C Levels in Critically Ill COVID-19 Patients

From [HERE] From the COVID-19 pandemic, we continue to learn about the critical importance of maintaining adequate levels of essential nutrients. When the body is under stress from an illness such as an infection, merely eating an excellent diet may not provide sufficient nutrients to support the immune system. To stave off a fast-moving infection may require higher levels of essential vitamins and minerals. Vitamin C has an essential role in empowering the immune system. Its oxidized form can be recycled by red blood cells (erythrocytes), but a fast-moving illness can overpower this system, causing vitamin C levels to precipitously drop.

A recent study in Spain measured plasma vitamin C levels in 67 critically ill hospitalized adult COVID-19 patients meeting the Berlin criteria for acute respiratory distress syndrome (ARDS).1 The results fell into three categories: undetectable (<0.1 mg/dL), low (0.1 – 0.4 mg/dL), and “normal” (0.4 – 2 mg/dL). Twelve (18%) patients had undetectable plasma vitamin C, 43 (64%) patients had low levels of plasma vitamin C (mean for this group was 0.14 mg/dL with a standard deviation of 0.05), and 12 (18%) patients had vitamin C levels within the normal range (mean for this group was 0.59 mg/dL with a standard deviation of 0.18). In summary, 82% of patients had low or undetectable plasma vitamin C levels, and 18% had values within the reference range, mostly on the low side of the reference range. (Riordon Clinic Bio-Center Laboratory has an established reference range of 0.6 – 2.0 mg/dL for plasma vitamin C). A smaller study of 18 adult COVID-19 patients with ARDS found similar results: 17 (94%) patients had undetectable plasma vitamin C, and 1 (6%) patient had a plasma vitamin C level of 0.24 mg/dL.2 The assay used in this study had a lower limit of detection of 0.15 mg/dL, above the mean of the low-level group in the first study.

Finding low levels of vitamin C in critically ill patients is not new and has been reported in a variety of studies over the last several decades. In 2017, a study of 44 critical care patients receiving recommended amounts of enteral and parenteral vitamin C (125 +/- 88 mg/day, max 448 mg/day) showed 70% of patients had vitamin C deficiency.3 Among septic shock patients, 90% had vitamin C deficiency. Borrelli et al published findings in 1996 showing that the lower the plasma ascorbic acid level in septic patients the greater the risk of organ failure and death.4 Even in presumed healthy people in the USA, vitamin C deficiency is found. In 2003-2004, NHANES samples from noninstitutionalized civilians found a vitamin C deficiency prevalence of 7.1% +/- 0.9%.5 This was a 44% reduction in vitamin C deficiency from the 1988 – 1994 national study. Smoking and low income were associated with higher rates of vitamin C deficiency. People in a deficient state can avoid acute illness for a time but have impaired capacity to respond to infections and other stress challenges.

Why Critically Ill People Require More Vitamin C to Maintain Adequate Levels of Plasma Vitamin C

Increased consumption. White blood cells, such as neutrophils and monocytes, actively take up ascorbic acid from plasma (fluid portion of blood) to achieve intracellular levels of 1 mM, 50-100 -fold higher than the typical vitamin C level of plasma. When stimulated to produce an oxidative burst, these white blood cells will pull in more vitamin C to increase intracellular concentrations ten-fold to 10 mM. If there is not enough vitamin C available, the white blood cell’s oxidative burst intended to kill an invading pathogen may destroy the WBC itself instead. Cytokines, inflammation, fever, and other biological stresses of illness also increase the metabolic demand for vitamin C throughout the body.6 [MORE]