A cohort study in the USA, suggests that butter and margarine consumption increases heart disease mortality while oilve oil reduces it.
A prospective study of cardiometabolic disease mortality and consumption of six oils and fats suggests butter and margarine increase mortality while olive oil reduces it and canola or corn oil had little effect. The study also suggests that substituting oils for butter or margarine would reduce cardiometabolic mortality. These findings support evidence from studies on individual fats and translate them to everyday food patterns. The study by Zhang and colleagues from Zhejiang University in China and the Karolinska Institute in Sweden is in BMC Medicine.
Dietary fats and heart disease have been under debate ever since the diet-heart hypothesis was proposed by Ancel Keys in the 1950’s. An article by Nita Forouchi and colleagues in BMJ (2018) explains the state of the debate highlighting the facts that that the type of fat as well as how much is consumed is important and what nutrient replaces a fat when it is reduced is also important. They also point out the need to base guidelines not on single nutrients but on foods.
Research on individual foods (as opposed to nutrients) and cardiometabolic mortality is sparse according to Yu Zhang and colleagues. They decided to explore the effects of 6 oils and fats on heart disease, stroke and diabetes mortality (cardiometabolic mortality) in a cohort study.
Zhang and colleagues used data from the NIH-AARP diet study. This study follows the health and diet of US men and women aged 50 years and above. The 567,169 participants completed a diet history questionnaire at the start of the study in 1995-1996 that asked questions about the fats they used in cooking and at table as well as the fat content of food they ate. They were then followed up until the end of 2011 and data collected on causes of death. Over that period 129,328 participants died.
The researchers constructed multivariable adjusted models. In those, butter and margarine consumption was strongly associated with all-cause and with cardiometabolic mortality (death from cardiovascular disease, stroke and diabetes) while olive oil was negatively associated with it. Compared with those who didn’t consume olive oil, those who consumed most olive oil had a 5% lower risk of CVD mortality while those who consumed most butter and margarine had 8% and 10% higher risks of CVD mortality. For diabetes, similar trends occurred. Those consuming the highest amounts of butter and margarine had an 18% higher risk of mortality from diabetes and those consuming the highest amounts of olive oil had a 13% lower risk of mortality from diabetes.
The researchers also modelled the effects of substituting 8 g of corn, canola or olive oils for the same amount of butter in the diet in study participants. The change reduced cardiometabolic mortality 5, 6, and 8% respectively.
The researchers conclude their study supports the current US diet recommendations to decrease butter intake: “Taken together, current dietary recommendations should continue to highlight shifting the intake from solid fats, including butter and margarine, to non-hydrogenated vegetable oils, such as corn oil, canola oil, and olive oil, for the prevention of cardiometabolic diseases and premature deaths.”
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Reference:
Zhang, Y., Zhuang, P., Wu, F. et al. Cooking oil/fat consumption and deaths from cardiometabolic diseases and other causes: prospective analysis of 521,120 individuals. BMC Medicine 19, 92 (2021). https://doi.org/10.1186/s12916-021-01961-2