Abstract
OBJECTIVES: Chronic inflammation is associated with obesity and chronic disease risk. Intake of dairy foods is associated with reduced risk of type 2 diabetes and cardiovascular disease; however, the impact of dairy intake on inflammation is not well established. The objective of this study was to conduct a systematic review of the literature to evaluate the effect of dairy product and dairy protein consumption on low-grade systemic inflammation in adults without severe inflammatory disorders. METHODS: This systematic review was conducted in accordance with the PRISMA statement and registered on PROSPERO (CRD42019129639). A literature search was completed in December 2018 and updated September 2019 using PubMed, CENTRAL, and review of reference lists from relevant review articles. The search resulted in identification and inclusion of 27 randomized controlled trials in this analysis, 19 trials which evaluated dairy products and 8 trials which evaluated dairy proteins. RESULTS: In the 19 trials which evaluated dairy products, 10 reported no inflammatory effect of the intervention, 8 reported a reduction in at least one biomarker of inflammation, and 1 reported a greater anti-inflammatory effect in the control as compared to the dairy product intervention. All 8 trials that investigated dairy protein intake on markers of inflammation reported no effect of the intervention. In the 17 trials which evaluated CRP following dairy product interventions, 12 studies reported no change, 4 studies in overweight and obese populations reported a decrease, and 1 study reported an increase in overweight and obese populations. In the 12 trials which evaluated an inflammatory-related cytokine (IL-6, TNF-α and receptors, IL-1β, and/or MCP-1), 7 studies reported no change in markers assessed, and 5 studies (4 of which were in overweight and obese populations) reported a decrease in at least one pro-inflammatory cytokine. A majority of the trials received neutral or positive quality ratings. CONCLUSIONS: The available literature suggests dairy products and dairy proteins have neutral to beneficial effects on biomarkers of inflammation. Additional clinical studies designed using an inflammatory biomarker as the primary outcome, are needed to fully elucidate the effects of dairy intake on inflammation. FUNDING SOURCES: National Dairy Council.