Based on a systematic review and search of multiple online academic and medical databases, the researchers identified nine eligible research studies including 15 country-specific cohorts representing 636,151 unique individuals with a total of 6.5 million person-years of follow-up. Over the total follow-up period, the combined group of studies included 28,271 deaths, 9,783 cases of cardiovascular disease, and 23,954 cases of new-onset type 2 diabetes. The researchers combined the nine studies into a meta-analysis of relative risk.
Butter consumption was standardized across all nine studies to 14 grams/day, which corresponds to one U.S. Department of Agriculture estimated serving of butter (or roughly one tablespoon). Overall, the average butter consumption across the nine studies ranged from roughly one-third of a serving per day to 3.2 servings per day. The study found mostly small or insignificant associations of each daily serving of butter with total mortality, cardiovascular disease, and diabetes.
“Even though people who eat more butter generally have worse diets and lifestyles, it seemed to be pretty neutral overall,” said Pimpin, now a data analyst in public health modelling for the UK Health Forum. “This suggests that butter may be a “middle-of-the-road” food: a more healthful choice than sugar or starch, such as the white bread or potato on which butter is commonly spread and which have been linked to higher risk of diabetes and cardiovascular disease; and a worse choice than many margarines and cooking oils – those rich in healthy fats such as soybean, canola, flaxseed, and extra virgin olive oils – which would likely lower risk compared with either butter or refined grains, starches, and sugars.”
“Overall, our results suggest that butter should neither be demonized nor considered “back” as a route to good health,” said Mozaffarian. “More research is needed to better understand the observed potential lower risk of diabetes, which has also been suggested in some other studies of dairy fat. This could be real, or due to other factors linked to eating butter – our study does not prove cause-and-effect.”
Additional authors of this study are Jason HY Wu, M.Sc., Ph.D., and Hila Haskelberg, Ph.D., both of The George Institute for Global Health, University of Sydney, Australia; and Liana Del Gobbo, Ph.D., formerly a postdoctoral fellow at the Friedman School and currently a research fellow in cardiovascular medicine at Stanford School of Medicine.
This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health, under award number 5R01HL085710. For conflicts of interest disclosure, please see the study.
Pimpin L, Wu JHY, Haskelberg H, Del Gobbo L, Mozaffarian D (2016) Is Butter Back? A Systematic Review and Meta-Analysis of Butter Consumption and Risk of Cardiovascular Disease, Diabetes, and Total Mortality. PLoS ONE 11(6): e0158118. doi:10.1371/journal.pone.0158118
About the Friedman School of Nutrition Science and Policy at Tufts UniversityThe Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school’s eight degree programs – which focus on questions relating to nutrition and chronic diseases, molecular nutrition, agriculture and sustainability, food security, humanitarian assistance, public health nutrition, and food policy and economics – are renowned for the application of scientific research to national and international policy.
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