Natural trans fats in dairy do not raise heart disease risk

Trans fats found naturally in dairy foods such as milk, butter and cheese do not increase the risk of heart disease or type 2 diabetes, a new study has found.

Researchers analysed evidence from 22 studies involving thousands of people across Europe, Canada and the United States

and found that natural trans fats behave very differently in the body from the industrial kind. Unlike industrial trans fats, which are strongly linked to heart disease, those found in dairy appear to pose no risk.

The first-of-its-kind research, published in the journal Nutrition Research, will also raise consumer’s awareness of this topic and provide clarity on trans fat labelling policies which may cause confusion.

Professor Ian Givens, one of lead authors, and from the University of Reading, said: “People hear the words ‘trans fats’ and assume the worst, but the trans fats in your morning milk, yogurt, butter or cheese are not the same as the ones from industrial partially hydrogenated fats. This research should give people reassurance that dairy, eaten as part of a balanced diet, is not something to worry about for your heart.”

Two types of trans fat, two different stories

Trans fats, a type of unsaturated fat, occur naturally in the milk of animals such as cows, sheep and goats, but can also be made artificially during the production of partially hydrogenated fats. The industrial type, can be found in some processed and fried foods, are strongly linked to heart disease.

To test whether dairy trans fats affect heart health, the researchers looked at two types of evidence. The first was ten dietary controlled trials in which people consumed dairy foods with naturally enhanced trans fats and compared with regular dairy foods. Scientists then measured the effect on blood lipid biomarkers, which are used to determine heart disease risk. Across all ten trials, covering trans fat intakes ranging from 1.3 to 13.2 grams per day, there were no meaningful differences in blood lipid levels between trans fat-enhanced dairy foods versus regular dairy foods.

The second type of evidence came from twelve long-term cohort studies that tracked thousands of people over many years, in some cases more than two decades, and measured the levels of dairy trans fats in their blood. None of these studies found that higher levels of dairy trans fats were linked to a greater risk of heart disease, stroke or cardiovascular death.

Likewise, higher levels of dairy trans fats in their blood were not linked with type 2 diabetes risk.