Vitamin C, which is present in oranges and other citrus fruits, may reduce the time some patients spend in the ICU.
Dr. Harri Hemilä of the University of Helsinki in Finland and Dr. Elizabeth Chalker of the University of Sydney in Australia have written a study paper that features in the journal Nutrients in which they explain how they found the "statistically highly significant evidence" that led to their conclusion.
A pooled analysis of data from a dozen trials found that giving patients vitamin C reduced time spent in the intensive care unit (ICU) by an average of 8 percent.
The authors are not claiming that the evidence is enough to justify changes to ICU practice.
They do, however, maintain that their findings serve as "proof of concept" and call for further research to investigate the effect of vitamin C on ICU patients.
"In further studies," they write, "the dose-response relationship should be carefully investigated, and oral and intravenous administration should be compared directly."
Critical care and vitamin C
The ICU is a hospital department that takes care of people who are critically ill with life-threatening conditions. There, they receive 24-hour care and life support from a specialized team.
Vitamin C is "crucial to human health." And yet, the human body depends entirely on dietary sources for its supply as it cannot make or store it.
Scientists have described vitamin C as a "functional food ingredient" because it is "biologically active" and has "clinically proven effects" that help to prevent, manage, and treat chronic diseases.
The ways that vitamin C works in the body are complex and intricate. The compound serves many roles in many processes. For instance, it helps make proteins that are essential for energy production in cells, maintains blood pressure, and has other cardiovascular functions. Also, through its ability to interact with DNA, vitamin C can activate and silence many genes.
Controlled trials have also revealed that, among other things, vitamin C can shorten the duration of the common cold, reduce blood glucose in people with diabetes, lower blood pressure, open constricted airways, and decrease rates of atrial fibrillation.
Because certain illnesses and conditions can result in dramatic reductions in the body's supply of vitamin C, people in hospitals often have very low levels of it in their blood.
For instance, infections, surgery, burns, and other types of physiological stress can cause a sudden drop in vitamin C because of the way they affect the body's metabolism.
To maintain blood levels of vitamin C that are on a par with those of healthy people, a critically ill individual needs to consume about 4 grams (g) of vitamin C per day. This is significantly more than the 0.1 g of daily vitamin C that a healthy person needs.
Vitamin C reduced time in ICU
Because of the widespread impact of vitamin C in the human body, and the fact that very ill people need much higher daily doses than healthy individuals, Drs. Hemilä and Chalker decided to investigate the evidence on how vitamin C impacts the length of time that people spend in the ICU.
By searching databases for published studies that could be relevant to such a question, the authors identified 18 controlled trials covering a total of 2,004 patients. Of these trials, 13 had investigated heart surgery patients.
A pooled analysis of 12 of the trials, which covered a total of 1,766 patients, revealed that administration of vitamin C cut the length of stay in the ICU by an average of 7.8 percent.
An analysis of six of the trials also revealed that giving patients doses of vitamin C ranging from 1 to 3 g per day cut time spent in the ICU by an average of 8.6 percent.
In three of the trials, the ICU patients had required more than 24 hours of "mechanical ventilation." An analysis of their data showed that vitamin C reduced the length of time people required mechanical ventilation by 18.2 percent.
The authors conclude:
"Given the insignificant cost of vitamin C, even an 8 percent reduction in ICU stay is worth exploring."