Family doctor

Butter has been flung into the dietary limelight by a recent, comprehensive study that has found it may not be as bad as we once thought. Contrary to popular belief, the study found only a weak association between butter consumption and overall mortality and found no association with increased heart disease, diabetes and stroke.

Butter contains a particularly high amount of saturated fat. Saturated fat is known to increase the risk of diabetes and heart disease, and it is for this reason that butter has been so strongly discouraged from our diets. However, the danger of butter on its own has never been clearly identified.

The study published in PLOS ONE journal, was a well-designed review of multiple studies that investigated the link between butter and outcomes such as overall mortality, heart disease and stroke. The study, known as a meta-analysis, synthesised the results of 9 studies over 15 countries and included data from more than 600,000 participants. Overall the study found that butter consumption was very weakly associated with mortality, giving a 1.01 increased risk of death per 1 tablespoon of butter a day. The study found no association between butter and heart disease, coronary artery disease or stroke, and found a mild, inverse relationship between butter and diabetes.

The trials included were all randomised controlled or prospective trials in adults with a follow up period of more than 3 months. For the studies to be included, the consumption of butter had to be distinguishable from other fat sources and the endpoints had to be easily measurable such as mortality or stroke rather than vague measures of heart disease. 28,000 total deaths occurred during the study periods as well as 10,000 new cases of heart disease, and 24,000 cases of diabetes. These volumes strengthen the study findings.

The study results come as a surprise to many health researchers, yet they are part of a growing body of evidence to suggest that our thinking needs to change about the harms of butter and fat. The study also calls us to recognise that a healthy diet is far less about individual components, than it is about overall eating patterns.

The 2015 dietary guidelines committee reflect this idea in their recommendation that we should focus on variability within our food, rather than focussing on specific nutrients. The guidelines still recommend replacing all saturated fats (including butter) with plant-based/vegetable oils containing mono and poly-unsaturated fats where possible.

Another recent study published in JAMA last month suggested that replacing just 5% of our saturated fat intake with mono or poly unsaturated fats could reduce mortality by 13% and 27% respectively.

While we’d be foolish to write the potential harms of butter off completely as saturated fats are still known to cause harm, the study is a step further in our understanding that fat is a lot more complex than originally imagined. It is not perhaps as definitively harmful as once thought. However, the consensus remains clear that mono and poly-unsaturated fats are better for our body than saturated fats. Butter may not be the enemy, but olive oil is certainly a kinder option.  

References:

1. Pimpin, Laura et al. "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 (2016): e0158118. Web. 20 Aug. 2016.

2. Wang, Dong D. et al. "Association Of Specific Dietary Fats With Total And Cause-Specific Mortality". JAMA Internal Medicine 176.8 (2016): 1134. Web. 20 Aug. 2016.