AUTHOR=Liu Fang-Hua , Liu Chuan , Gong Ting-Ting , Gao Song , Sun Hui , Jiang Yu-Ting , Zhang Jia-Yu , Zhang Meng , Gao Chang , Li Xin-Yu , Zhao Yu-Hong , Wu Qi-Jun 

TITLE=Dietary Inflammatory Index and Health Outcomes: An Umbrella Review of Systematic Review and Meta-Analyses of Observational Studies

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.647122

DOI=10.3389/fnut.2021.647122

ISSN=2296-861X

ABSTRACT=<p><bold>Background and Aims:</bold> The dietary inflammatory index (DII) is associated with non-communicable disease. We conducted an umbrella review to systematically evaluate meta-analyses of observational studies on DII and diverse health outcomes.</p><p><bold>Methods:</bold> We comprehensively searched the PubMed, Web of Science, and Embase databases to identify related systematic reviews and meta-analyses of observational studies. Those investigating the association between DII and a wide range of health outcomes in humans were eligible for inclusion. For each meta-analysis, we estimated the summary effect size by using fixed and random effects models, the 95% confidence interval, and the 95% prediction interval. We assessed heterogeneity, evidence of small-study effects, and excess significance bias.</p><p><bold>Results:</bold> The umbrella review identified 35 meta-analyses assessing associations between DII and various health outcomes: cancer (<italic>n</italic> = 24), mortality (<italic>n</italic> = 4), metabolic (<italic>n</italic> = 4), and other (<italic>n</italic> = 3). The methodological quality was high or moderate. Of the 35 meta-analyses, we observed highly suggestive evidence for harmful associations between digestive tract cancer, colorectal cancer, overall cancer, pharyngeal cancer, UADT cancer, and CVD mortality. Moreover, 11 harmful associations showed suggestive evidence: hormone-dependent cancer, rectal cancer, colon cancer, breast and prostate cancer, gynecological cancer, breast cancer, ovarian cancer, colorectal cancer, prostate cancer, all-cause mortality, and depression.</p><p><bold>Conclusion:</bold> DII is likely to be associated with harmful effects in multiple health outcomes. Robust randomized controlled trials are warranted to understand whether the observed results are causal.</p><p><bold>Systematic Review Registration:</bold> CRD42021218361</p>