Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes

Crit Care. 2017 Dec 11;21(1):300. doi: 10.1186/s13054-017-1891-y.

Abstract

Background: Vitamin C is an essential water-soluble nutrient which cannot be synthesised or stored by humans. It is a potent antioxidant with anti-inflammatory and immune-supportive roles. Previous research has indicated that vitamin C levels are depleted in critically ill patients. In this study we have assessed plasma vitamin C concentrations in critically ill patients relative to infection status (septic shock or non-septic) and level of inflammation (C-reactive protein concentrations). Vitamin C status was also assessed relative to daily enteral and parenteral intakes to determine if standard intensive care unit (ICU) nutritional support is adequate to meet the vitamin C needs of critically ill patients.

Methods: Forty-four critically ill patients (24 with septic shock, 17 non-septic, 3 uncategorised) were recruited from the Christchurch Hospital Intensive Care Unit. We measured concentrations of plasma vitamin C and a pro-inflammatory biomarker (C-reactive protein) daily over 4 days and calculated patients' daily vitamin C intake from the enteral or total parenteral nutrition they received. We compared plasma vitamin C and C-reactive protein concentrations between septic shock and non-septic patients over 4 days using a mixed effects statistical model, and we compared the vitamin C status of the critically ill patients with known vitamin C bioavailability data using a four-parameter log-logistic response model.

Results: Overall, the critically ill patients exhibited hypovitaminosis C (i.e., < 23 μmol/L), with a mean plasma vitamin C concentration of 17.8 ± 8.7 μmol/L; of these, one-third had vitamin C deficiency (i.e., < 11 μmol/L). Patients with hypovitaminosis C had elevated inflammation (C-reactive protein levels; P < 0.05). The patients with septic shock had lower vitamin C concentrations and higher C-reactive protein concentrations than the non-septic patients (P < 0.05). Nearly 40% of the septic shock patients were deficient in vitamin C, compared with 25% of the non-septic patients. These low vitamin C levels were apparent despite receiving recommended intakes via enteral and/or parenteral nutritional therapy (mean 125 mg/d).

Conclusions: Critically ill patients have low vitamin C concentrations despite receiving standard ICU nutrition. Septic shock patients have significantly depleted vitamin C levels compared with non-septic patients, likely resulting from increased metabolism due to the enhanced inflammatory response observed in septic shock.

Keywords: C-reactive protein; Critical illness; Enteral nutrition; Hypovitaminosis C; Intensive care; Parenteral nutrition; Sepsis; Septic shock; Vitamin C.

Publication types

  • Observational Study

MeSH terms

  • Aged
  • Ascorbic Acid / metabolism
  • Ascorbic Acid / pharmacokinetics*
  • Ascorbic Acid / therapeutic use
  • Ascorbic Acid Deficiency / drug therapy*
  • Ascorbic Acid Deficiency / prevention & control
  • Biomarkers / analysis
  • Biomarkers / blood
  • C-Reactive Protein / analysis
  • Critical Illness / therapy*
  • Enteral Nutrition / methods
  • Female
  • Humans
  • Intensive Care Units / organization & administration
  • Male
  • Middle Aged
  • New Zealand
  • Nutritional Requirements / drug effects*
  • Nutritional Requirements / physiology
  • Organ Dysfunction Scores
  • Parenteral Nutrition / methods
  • Shock, Septic / complications
  • Shock, Septic / diet therapy

Substances

  • Biomarkers
  • C-Reactive Protein
  • Ascorbic Acid