Dietary Supplements

Effects of Nutritional Supplements on Inflammatory Biomarkers in Overweight and Obese Adults: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials.

TL;DR

Probiotics combined with omega-3 fatty acids, synbiotics, green tea extract, and curcumin may improve selected inflammatory biomarkers in overweight and obese adults, though effects were biomarker-specific and warrant cautious interpretation.

Key Findings

Green tea extract and curcumin both significantly reduced IL-6 levels compared to placebo in overweight and obese adults.

  • Green tea extract reduced IL-6 with MD = -2.57 (95% CI [-3.99, -1.15])
  • Curcumin reduced IL-6 with MD = -1.75 (95% CI [-2.74, -0.76])
  • Analysis was based on 60 randomized controlled trials included in the network meta-analysis
  • A frequentist random-effects network meta-analysis framework was used, with effects reported as mean differences with 95% confidence intervals

Synbiotics, curcumin, and probiotics combined with omega-3 fatty acids all significantly reduced TNF-α levels.

  • Synbiotics showed the largest reduction in TNF-α: MD = -12.25 (95% CI [-16.7, -7.8])
  • Probiotics combined with omega-3 showed MD = -6.19 (95% CI [-9.12, -3.26])
  • Curcumin reduced TNF-α with MD = -2.59 (95% CI [-3.83, -1.35])
  • Interventions were ranked using the surface under the cumulative ranking curve (SUCRA)

Four nutritional supplements — probiotics combined with omega-3, synbiotics, zinc, and curcumin — significantly reduced CRP levels.

  • Probiotics combined with omega-3 showed the greatest CRP reduction: MD = -1.74 (95% CI [-3.03, -0.46])
  • Synbiotics reduced CRP with MD = -1.19 (95% CI [-1.85, -0.53])
  • Zinc reduced CRP with MD = -1.18 (95% CI [-2.24, -0.11])
  • Curcumin reduced CRP with MD = -1.11 (95% CI [-2.14, -0.07])

Synbiotics significantly increased adiponectin levels in overweight and obese adults.

  • Synbiotics increased adiponectin with MD = 15.37 (95% CI [12.13, 18.61])
  • No other nutritional supplement was reported to significantly increase adiponectin levels
  • Adiponectin is an anti-inflammatory adipokine implicated in metabolic function

No nutritional supplement examined in the network meta-analysis significantly reduced leptin levels.

  • Leptin was one of the inflammatory biomarkers assessed across the 14 supplementation strategies
  • The finding contrasts with the significant effects observed for IL-6, TNF-α, CRP, and adiponectin
  • This null finding applied across all 14 supplementation strategies evaluated

Exploratory meta-regression suggested that age, exercise co-interventions, and the proportion of male participants may partly explain heterogeneity in selected outcomes.

  • Meta-regression was described as exploratory in nature
  • Three moderating variables were identified: participant age, presence of exercise co-interventions, and proportion of male participants
  • These variables were examined in the context of selected, not all, outcomes
  • The analysis was conducted within a frequentist random-effects framework

The systematic review included 60 randomized controlled trials examining 14 supplementation strategies against inflammatory biomarkers in overweight or obese adults.

  • Literature search covered PubMed, Embase, EBSCO, Web of Science, and the Cochrane Library
  • Trials published between January 2000 and January 2026 were eligible
  • Confidence in network estimates was assessed using the Confidence in Network Meta-Analysis (CINeMA) framework
  • Supplementation strategies included green tea extract, curcumin, synbiotics, probiotics combined with omega-3, zinc, and others up to 14 total interventions

The authors concluded that nutritional supplement effects were biomarker-specific, and that differences in supplement dose, intervention duration, and participant characteristics warrant cautious interpretation.

  • Effects differed across IL-6, TNF-α, CRP, adiponectin, and leptin outcomes
  • Authors called for further high-quality trials to clarify these relationships
  • The study addressed a gap in comparative evidence, as prior literature had not clearly ranked 14 supplementation strategies head-to-head on inflammatory biomarkers in this population

What This Means

This research suggests that certain nutritional supplements can help reduce markers of inflammation in people who are overweight or obese, but the benefits depend on which specific marker is being measured. The study pooled data from 60 clinical trials comparing 14 different supplement types. It found that green tea extract and curcumin (the active compound in turmeric) reduced levels of IL-6, an inflammatory protein. Synbiotics (a combination of probiotics and prebiotics), curcumin, and probiotics taken with omega-3 fatty acids reduced TNF-α, another inflammation marker. CRP, a commonly measured inflammation marker, was lowered by probiotics with omega-3, synbiotics, zinc, and curcumin. Synbiotics also raised adiponectin, a hormone associated with better metabolic health. Notably, none of the supplements significantly reduced leptin, a hormone related to appetite regulation and fat storage. This research matters because chronic low-grade inflammation associated with excess body weight is linked to conditions like type 2 diabetes and cardiovascular disease. Finding supplements that can safely reduce this inflammation could be a meaningful tool in managing metabolic health. However, the results varied depending on which inflammatory marker was studied, and the researchers noted that differences in supplement dosages, how long people took them, and participant characteristics make it difficult to draw firm conclusions. The study's authors emphasize that these findings should be interpreted cautiously and that more high-quality clinical trials are needed before strong recommendations can be made. Factors like a person's age, sex, and whether they were also exercising appeared to influence results, which highlights that the effects of these supplements are likely not one-size-fits-all.

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Citation

Chen Z, Liu A, Bian S, Zhou Z, Zhang D. (2026). Effects of Nutritional Supplements on Inflammatory Biomarkers in Overweight and Obese Adults: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials.. Nutrients. https://doi.org/10.3390/nu18172936