Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis

source extracted confidence: high 2026-04-09
#cytokines #dietary-supplements #female #flavonoids #humans

Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis

Somerville et al., 2016 | Adv Nutr | Meta Analysis

Citation

Somerville Vaughan S, Braakhuis Andrea J, Hopkins Will G. Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis. Adv Nutr. 2016-May;7(3):488-97. doi:10.3945/an.115.010538

Abstract

Previous research on animals indicates flavonoid compounds have immunomodulatory properties; however, human research remains inconclusive. The aim of this systematic review was to assess the efficacy of dietary flavonoids on upper respiratory tract infections (URTIs) and immune function in healthy adults. A created search strategy was run against Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and EMBASE classic, CINAHL, and AMED. The returned studies were initially screened, and 2 reviewers independently assessed the remaining studies for eligibility against prespecified criteria. Fourteen studies, of 387 initially identified, were included in this review, and the primary outcome measure was the effect of flavonoids on URTI incidence, duration, and severity. Of the included studies, flavonoid supplementation ranged from 0.2 to 1.2 g/d. Overall, flavonoid supplementation decreased URTI incidence by 33% (95% CI: 31%, 36%) compared with control, with no apparent adverse effects. Sick-day count was decreased by 40% with flavonoid supplementation, although unclear. Differences in bio-immune markers (e.g., interleukin-6, tumor necrosis factor-α, interferon-γ, neutrophils) were trivial between the intervention and control groups during the intervention and after exercise when a postintervention exercise bout was included. These findings suggest that flavonoids are a viable supplement to decrease URTI incidence in an otherwise healthy population.

Key Findings

These findings suggest that flavonoids are a viable supplement to decrease URTI incidence in an otherwise healthy population.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population healthy adults
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Cytokines
  • Dietary Supplements
  • Female
  • Flavonoids
  • Humans
  • Immunity
  • Male
  • Neutrophils
  • Phytotherapy
  • Plant Extracts
  • Respiratory Tract Infections

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Systematic Review
  • Vertical: quercetin

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09