Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes.
Level 3 - non-randomized controlled study
Prospective observational cohort study comparing septic shock and non-septic ICU subgroups
PubMed 29228951 · doi:10.1186/s13054-017-1891-y
What was done
Researchers measured daily plasma vitamin C and C-reactive protein (CRP) concentrations over 4 days in 44 critically ill patients (24 with septic shock, 17 non-septic, and 3 uncategorised) admitted to the Christchurch Hospital Intensive Care Unit. Daily vitamin C intake from enteral or parenteral nutrition was recorded. Differences between septic shock and non-septic patients were evaluated using mixed-effects statistical models, and vitamin C bioavailability was evaluated against a four-parameter log-logistic response model.
What was found
Across the cohort, mean plasma vitamin C concentration was 17.8 ± 8.7 μmol/L, meeting the threshold for hypovitaminosis C (< 23 μmol/L), and one-third of all patients had severe deficiency (< 11 μmol/L) despite receiving standard nutritional therapy providing a mean intake of 125 mg/day. Patients with hypovitaminosis C had significantly higher CRP levels (P < 0.05). Compared to non-septic patients, those with septic shock had significantly lower plasma vitamin C concentrations and higher CRP levels (P < 0.05), with nearly 40% meeting deficiency criteria versus 25% of non-septic patients.
Why it matters
This study indicates that standard ICU nutritional guidelines and formulas supplying baseline vitamin C intakes (~100–125 mg/day) do not maintain normal plasma concentrations in critically ill patients, particularly during septic shock where inflammatory consumption is heightened.
Limits
The sample size was small (n = 44) and recruited from a single intensive care unit over a short observation window (4 days). Clinical outcomes associated with deficiency were not evaluated, and 3 patients remained uncategorised in the subgroup analysis.
Cited by
- supports Critically ill patients with conditions such as viral infections can have plasma vitamin C levels that are less than 25% of the levels observed in healthy individuals.