Abstract 27: Is Butter Back? A Systematic Review and Meta-analysis of Butter Consumption and Risk of Cardiovascular Disease, Diabetes, and Total Mortality

Abstract

Introduction: Dietary guidelines recommend avoiding foods high in saturated fat. Yet, emerging evidence suggests potential cardiometabolic benefits of dairy products and dairy fat. Evidence on the role of butter, with high saturated dairy fat content, for total mortality, CVD, and diabetes remains unclear. Objective: To systematically investigate the prospective association of butter consumption with all-cause mortality, CVD, and type 2 diabetes. Methods: We searched 9 databases from inception to May 2015 without restriction on publication year, setting, or language, using keywords related to butter intake and outcomes of interest. We included prospective cohorts or randomized clinical trials providing estimates of effects of butter intake on mortality, CVD (including CHD or stroke), or diabetes in general adult populations. Inclusion decisions and data extractions were performed independently and in duplicate, including on study and participant characteristics, exposure and outcome definitions and assessments, analysis methods, and adjusted risk estimates and uncertainty of prospective multivariate associations. Study quality was evaluated by a modified Newcastle-Ottawa score. Findings were pooled by random and fixed effects meta-analysis, with heterogeneity assessed by the I2 statistic and publication bias by Egger’s test and funnel plots. Results: We identified 9 publications including 15 country-specific cohorts, with 636,151 unique participants, 6.5 million person-years of follow-up, and 28,271 total deaths, 9,783 cases of incident CVD, and 23,954 cases of incident diabetes. Quality ratings were high for all studies. Butter consumption was weakly associated with all-cause mortality (N=9 country-specific cohorts; per 14 g (1 tablespoon)/day: RR=1.01, 95%CI=1.00, 1.03, P=0.045); was not significantly associated with any CVD (N=4; RR=1.00, 95%CI=0.98, 1.02; P=0.79), CHD (N=3; RR=0.99, 95%CI=0.96, 1.03; P=0.605), or stroke (N=3; RR=1.00, 95%CI=0.98, 1.03; P=0.79), and was inversely associated with incidence of diabetes (N=11; RR=0.96, 95%CI=0.93, 0.99; P=0.02). We did not identify evidence for heterogeneity nor publication bias. Conclusions: This systematic review and meta-analysis identified a weak association of butter intake with total mortality, no association with CVD, and a modest protective association with diabetes. The studies identified indicate that many global cohorts have not reported on these associations; if publication bias exists, it would likely be for unpublished reports with null findings, rather than significant associations. In sum, these results suggest relatively neutral effects of butter consumption on major health outcomes, with a possible modest benefit for diabetes.