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High intake of saturated fats is linked to increased risk of heart disease

BMJ 2016; 355 doi: (Published 24 November 2016) Cite this as: BMJ 2016;355:i6347
  1. Jacqui Wise

Eating more saturated fatty acids such as those found in cheese, whole milk, butter, beef, and chocolate, is associated with an increased risk of coronary heart disease, a large observational study published in The BMJ has found.1

Researchers from Harvard University, USA, found that a 5% higher intake of longer chain dietary saturated fatty acids was associated with a 25% increased risk of coronary heart disease during 24 to 28 years of follow-up.

The team analysed data from two longitudinal cohort studies: the Health Professionals Follow-Up Study, which included 42 625 men from 1986 to 2010, and the Nurses Health Study, which included 73 147 women from 1984 to 2012. All participants were free of major chronic diseases at baseline and completed a detailed food questionnaire every four years.

The participants self reported any coronary heart disease, but this was confirmed by examining medical records. Fatal coronary heart disease was identified by searching the National Death Index or through reports from next of kin, which were then confirmed by a review of hospital records. A total of 7035 incident cases of coronary heart disease were identified, of which 2687 cases were fatal.

The mean intake of saturated fatty acids accounted for 9.0-11.3% of energy intake and mainly comprised lauric acid, myristic acid, palmitic acid, and stearic acid. Participants with the highest intake of total saturated fatty acids had a higher risk of coronary heart disease than those in the lowest intake group (hazard ratio 1.18 (confidence interval 1.09 to 1.28); P trend<0.001) after adjustment for lifestyle factors and total energy intake. When considered separately, each saturated fatty acid was associated with an increased risk of coronary heart disease.

Using statistical models, the researchers calculated that replacing 1% of the daily energy intake from saturated fatty acids with equivalent energy from unsaturated fats, whole grain carbohydrates, or plant proteins would reduce the coronary heart disease risk by 6-8%. Replacing 1% of the daily energy intake from palmitic acid was associated with a 10-12% reduction in this risk.

The researchers calculated that, if saturated fat intake decreased from the highest level to the lowest, the absolute risk reductions in coronary heart disease per 100 000 person years would be 106 cases if it was replaced by polyunsaturated fat, 71 cases if replaced by monounsaturated fat, 83 cases if replaced by whole grain carbohydrates, and 95 cases if replaced by plant proteins.

The researchers said that their study supports current dietary guidelines that focus on reducing total saturated fat intake through unsaturated fats—for example, by replacing animal fats, such as butter and lard, with vegetable oils high in unsaturated fat, such as olive oil.

They added that palm oil has increased in use in recent years, particularly in developing countries and in snacks and bakery products, and that this trend might lead to adverse consequences.


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