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Glutamine supplementation in serious illness


Clinical bottom line

There is no convincing evidence that glutamine supplementation in serious illness has any significant benefit.

Although glutamine is an amino acid synthesised in large quantities in normal circumstances, it has been hypothesised that glutamine could become a conditionally essential amino acid when synthesis is reduced in serious illness. Supplementation with glutamine might therefore be expected to improve outcomes.


F Novak et al. Glutamine supplementation in serious illness: a systematic review of the evidence. Critical Care Medicine 2002 30: 2022-2029.

Systematic review

There was a thorough search for studies involving glutamine supplementation compared with placebo or standard care in randomised trials. The search included the Cochrane register. Included studies had to be randomised, involve elective surgical or critically ill adult patients, and have as outcomes mortality, complications, or length of stay. Methodological quality was assessed using a 14-point scale.


Critical illness

There were six studies, five of which had quality scores above 8/14 (413 patients (Figure 1). Overall there was no significant difference between mortality with glutamine (48/207, 23%) and with usual care (62/206, 30%). The relative risk was 0.8 (95% confidence interval 0.6 to 1.1). There was no difference in infectious complications (three trials) or length of hospital stay (four trials).

Figure 1: Trials of glutamine supplementation compared with control in critically ill patients


There were eight studies, only two of which had quality scores above 8/14. In the eight trials one patient died with glutamine and one with control. Infectious complications were few. Length of hospital stay appeared to be shorter with glutamine, but with only two small trials likely to be unbiased, this was impossible to interpret.


The evidence for using glutamate is not convincing. Trials were generally of low quality, and where quality was adequate there was no difference in mortality. This may not rule out some small difference, perhaps in length of stay after surgery, but more substantial studies would be needed to demonstrate this.