Whey supplementation is beneficial for human health, possibly by reducing the circulating C-reactive protein (CRP) level, a sensitive marker of inflammation. Thus, a meta-analysis of randomized controlled trials was conducted to evaluate their relationship. A systematic literature search was conducted in July, 2014, to identify eligible studies. Either a fixed-effects model or a random-effects model was used to calculate pooled effects. The meta-analysis results of nine trials showed a slight, but no significant, reduction of 0.42 mg/L (95% CI −0.96, 0.13) in CRP level with the supplementation of whey protein and its derivates. Relatively high heterogeneity across studies was observed. Subgroup analyses showed that whey significantly lowered CRP by 0.72 mg/L (95% CI −0.97, −0.47) among trials with a daily whey dose ≥20 g/day and by 0.67 mg/L (95% CI −1.21, −0.14) among trials with baseline CRP ≥3 mg/L. Meta-regression analysis revealed that the baseline CRP level was a potential effect modifier of whey supplementation in reducing CRP. In conclusion, our meta-analysis did not find sufficient evidence that whey and its derivates elicited a beneficial effect in reducing circulating CRP. However, they may significantly reduce CRP among participants with highly supplemental doses or increased baseline CRP levels.

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Context A high amount of red meat consumption has been associated with higher risks of coronary heart disease (CHD) and all-cause mortality in a single food-exposure model. However, this model may overlook the potentially differential influence of red meat on these outcomes depending on the foods replaced by red meat. Objective A PRISMA-compliant meta-analysis of prospective observational studies was performed to quantify the risks of CHD and all-cause mortality associated with the replacement of total, unprocessed, or processed red meat with fish/seafood, poultry, dairy, eggs, nuts, and legumes. Data sources The PubMed and Web of Science databases were searched to identify relevant articles published in any language from database inception to October 30, 2021. Data extraction The prospective observational studies were considered relevant if they reported relative risks (RRs) and 95%CIs for the associations of interest. Data analysis Thirteen articles were included. A random-effects model was used to estimate the summary RRs and 95%CIs for the associations of interest. Replacing total red meat with poultry (RR, 0.88, 95%CI, 0.82–0.96; I2 = 0%), dairy (RR, 0.90, 95%CI, 0.88–0.92; I2 = 0%), eggs (RR, 0.86, 95%CI, 0.79–0.94; I2 = 7.1%), nuts (RR, 0.84, 95%CI, 0.74–0.95; I2 = 66.8%), or legumes (RR, 0.84, 95%CI, 0.74–0.95; I2 = 7.3%) was associated with a lower risk of CHD, whereas substituting fish/seafood (RR, 0.91, 95%CI, 0.79–1.04; I2 = 69.5%) for total red meat was not associated with the risk of CHD. The replacement of total red meat with fish/seafood (RR, 0.92, 95%CI, 0.89–0.96; I2 = 86.9%), poultry (RR, 0.92, 95%CI, 0.90–0.95; I2 = 61.6%), eggs (RR, 0.91, 95%CI, 0.87–0.95; I2 = 33.8%), or nuts (RR, 0.92, 95%CI, 0.87–0.97; I2 = 81.9%) was associated with a lower risk of all-cause mortality, whereas the substitution of dairy (RR, 0.97, 95%CI, 0.93–1.01; I2 = 33.9%) or legumes (RR, 0.97, 95%CI, 0.93–1.01; I2 = 53.5%) for total red meat was not associated with the risk of all-cause mortality. Lower risks of CHD and all-cause mortality were more consistently observed for processed red meat replacements than for unprocessed red meat replacements. The results did not materially change when the analyses of total, processed, and unprocessed red meat were restricted to the studies that used a uniform substitution amount per unit of 1 serving/d. Conclusion Keeping red meat, particularly processed red meat, consumption to a minimum along with increasing healthier alternative protein sources to replace red meat in the diet may contribute to the prevention of CHD and premature death. Systematic review registration PROSPERO registration no. CRD42021259446.