Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes
Open accessAbstract
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.
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Septic patients typically have very low or undetectable serum levels of vitamin C despite recommended enteral and parenteral intakes.
“Septic patients typically have very low or undetectable serum levels of vitamin C despite recommended enteral and parenteral intakes [80].”
From Nutrition in Sepsis: A Bench-to-Bedside Review. (2020) · cites this paper as [80]
The Results (Plasma vitamin C status of critically ill patients; page unavailable) report low plasma vitamin C in septic shock patients: 88% had hypovitaminosis C despite recommended enteral and/or parenteral intakes. The study measured plasma rather than serum, studied septic shock rather than septic patients generally, and does not report that levels were undetectable. (LLM, conf=0.87)
Experimental — accuracy not yet measuredVitamin C is crucial for immune system function.
“Vitamin C is crucial for immune system function [1,2,3,4] and protects against damage from reactive oxygen species [5,6].”
From Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement Forms in Healthy Adults (2025) · cites this paper as [3]
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- Authors
- Carr, A. C., Rosengrave, P. C., Bayer, S., Chambers, S., Mehrtens, J., & Shaw, G. M.
- Affiliations
- University of Otago (NZ)
- Christchurch Hospital (NZ)
- Corresponding author
- Carr, Anitra C.
- Venue
- Critical Care
- Published
- 2017-12
- Volume
- 21
- Issue
- 1
- Pages
- 300-300
- ISSN
- 1364-8535 (ISSN-L)
- PMC
- PMC5725835
- OpenAlex
- W2773432284
- Cited by
- 413
- References
- 56
- Citations by year
- 2026: 24 · 2025: 27 · 2024: 35 · 2023: 51 · 2022: 59 · 2021: 76 · 2020: 69 · 2019: 39 · 2018: 32 · 2017: 1
- FWCI
- 32.06
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- cc-by
- Locations
- Critical Care (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- Health Research Council of New Zealand (16/037)
- Canterbury Medical Research Foundation (15/06)
- Intensive Care Foundation
- Topics
- Health Sciences › Nursing › Nutrition and Dietetics › Vitamin C and Antioxidants Research
- Health Sciences › Nursing › Nutrition and Dietetics › Clinical Nutrition and Gastroenterology
- Health Sciences › Medicine › Biochemistry › Antioxidant Activity and Oxidative Stress
- Keywords
- scurvy, hypovitaminosis C, critically ill patients, septic shock, C-reactive protein, inflammation, plasma vitamin C concentration, enteral nutrition, parenteral nutrition, intensive care nutrition, vitamin C intake, vitamin C metabolism
- MeSH terms
- Aged, Ascorbic Acid, Ascorbic Acid Deficiency, C-Reactive Protein, Enteral Nutrition, Female, Humans, Intensive Care Units, Male, Middle Aged, New Zealand, Nutritional Requirements, Parenteral Nutrition, Shock, Septic, Biomarkers, Critical Illness, Organ Dysfunction Scores
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