Vitamin C and Neutrophil Function: Findings from Randomized Controlled Trials.

Area of Science:

• Immunology
• Nutritional Science
• Cell Biology

Background:

• Vitamin C (ascorbic acid) is crucial for immune function, accumulating in neutrophils to millimolar concentrations.
• Neutrophils play a vital role in the innate immune system, responding to pathogens and injury.
• Understanding vitamin C's influence on neutrophil function is key to optimizing immune responses.

Purpose of the Study:

• To systematically review randomized controlled trials (RCTs) assessing vitamin C's effects on neutrophil function.
• To evaluate vitamin C's impact as a mono- or multi-supplement therapy on neutrophil migration, phagocytosis, oxidative burst, enzyme activity, and apoptosis.

Main Methods:

• Systematic literature search across multiple databases (e.g., PubMed, EMBASE, CINAHL) for eligible RCTs.
• Inclusion of 16 RCTs assessing primary or secondary outcomes related to neutrophil function.
• Quality appraisal using the Cochrane Risk of Bias tool.

Main Results:

• Two of three studies on neutrophil chemotaxis showed improvement with intravenous vitamin C.
• Ten RCTs on phagocytosis/oxidative burst yielded mixed results, with some showing increased activity in athletes and decreased oxidant generation in myocardial infarction patients.
• One study indicated decreased neutrophil apoptosis in septic surgical patients receiving intravenous vitamin C.

Conclusions:

• Approximately 44% of reviewed RCTs demonstrated effects of vitamin C supplementation on neutrophil functions.
• Significant heterogeneity in participant cohorts and dosing regimens across studies limits definitive conclusions.
• Future RCTs should focus on specific populations with low vitamin C status and optimized dosing strategies.