Vitamin C and Neutrophil Function: Findings from Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review of randomized controlled trials
PubMed 31487891 · doi:10.3390/nu11092102
What was done
A systematic review was conducted across nine databases (including PubMed, EMBASE, and Cochrane CENTRAL) to identify randomized controlled trials evaluating mono- or multi-supplement vitamin C on neutrophil chemotaxis, phagocytosis, oxidative burst, enzyme activity, or apoptosis. Quality appraisal was performed using the Cochrane Risk of Bias tool. Sixteen RCTs met inclusion criteria.
What was found
Overall, 44% of the 16 included RCTs reported an effect of vitamin C supplementation on neutrophil function. Two of 3 trials evaluating chemotaxis reported improvements following intravenous administration in hospitalized patients or outpatients. Two of 10 trials evaluating phagocytosis or oxidative burst showed differences: increased post-exercise oxidative burst in athletes and decreased oxidant generation in myocardial infarction patients (both multi-supplement regimens). Two trials showed altered antioxidant enzyme activity (decreased in divers, increased in athletes), and one trial observed decreased neutrophil apoptosis in septic surgical patients receiving intravenous vitamin C.
Why it matters
Neutrophils accumulate millimolar concentrations of vitamin C, but clinical trial evidence for functional enhancement remains inconsistent and varies widely by patient health status, co-supplements, and administration route.
Limits
The included studies exhibited marked clinical heterogeneity in participant populations (ranging from healthy volunteers and athletes to surgical and myocardial infarction patients), dosing regimens, and co-supplementations. Most studies did not prescreen participants for baseline vitamin C deficiency. Total aggregate participant sample size across the 16 RCTs was not reported in the abstract.
Cited by
- supports Neutrophils and leukocytes have vitamin C concentrations between 50 to 100 times higher than plasma.