Effects of whey and soy protein supplementation on inflammatory cytokines in older adults: a systematic review and meta-analysis
What this study found
Overall, whey and soy protein showed modest, biomarker-specific anti-inflammatory effects rather than broad reductions across all markers. Whey protein was associated with lower IL-6 overall (MD -0.79 pg/ml, 95% CI -1.15 to -0.42), while effects on CRP, hs-CRP, and TNF-alpha were not statistically clear. Soy protein was associated with a reduction in TNF-alpha (MD -0.16 pg/mL, 95% CI -0.26 to -0.05), and adding isoflavones further lowered TNF-alpha (MD -0.20, 95% CI -0.31 to -0.08) but increased CRP in one subgroup analysis (MD 0.53, 95% CI 0.12 to 0.94). Benefits appeared more evident in…
- Study & population
- Systematic review and meta-analysis of 31 studies involving 3274 participants, with 1611 in intervention arms and 1663 in comparators.
- Intervention
- Included trials evaluated isolated whey protein or soy protein supplementation, usually taken orally once daily for 6 weeks to 24 weeks, with doses ranging from 15 g/d to 52 g/d.
- Key limitation
- Results were limited by substantial heterogeneity for several outcomes, especially whey IL-6 and CRP and soy CRP and hs-CRP.
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Open PDFOriginal abstract
Abstract Background and aims: Low-grade inflammation is a mediator of muscle proteostasis. This study aimed to investigate the effects of isolated whey and soy proteins on inflammatory markers. Methods: We conducted a systematic literature search of randomised controlled trials (RCT) through MEDLINE, Web of Science, Scopus and Cochrane Library databases from inception until September 2021. To determine the effectiveness of isolated proteins on circulating levels of C-reactive protein (CRP), IL-6 and TNF-α, a meta-analysis using a random-effects model was used to calculate the pooled effects (CRD42021252603). Results: Thirty-one RCT met the inclusion criteria and were included in the systematic review and meta-analysis. A significant reduction of circulating IL-6 levels following whey protein [Mean Difference (MD): −0·79, 95 % CI: −1·15, −0·42, I2 = 96 %] and TNF-α levels following soy protein supplementation (MD: −0·16, 95 % CI: −0·26, −0·05, I2 = 68 %) was observed. The addition of soy isoflavones exerted a further decline in circulating TNF-α levels (MD: −0·20, 95 % CI: −0·31, −0·08, I2 = 34 %). According to subgroup analysis, whey protein led to a statistically significant decrease in circulating IL-6 levels in individuals with sarcopenia and pre-frailty (MD: −0·98, 95 % CI: −1·56, −0·39, I2 = 0 %). These findings may be dependent on participant characteristics and treatment duration. Conclusions: These data support that whey and soy protein supplementation elicit anti-inflammatory effects by reducing circulating IL-6 and TNF-α levels, respectively. This effect may be enhanced by soy isoflavones and may be more prominent in individuals with sarcopenia.