- A review of 22 studies found no clear evidence that naturally occurring trans fats in dairy products increase the risk of heart disease, stroke, cardiovascular death, or type 2 diabetes.
- Unlike industrially produced trans fats, naturally occurring trans fats found in foods such as milk, cheese, butter, and yogurt may affect the body differently and did not significantly worsen cholesterol or other cardiovascular risk markers.
- The findings suggest that current concerns around trans fats may not apply equally to naturally occurring dairy trans fats, highlighting the importance of distinguishing between industrial and natural sources.
Trans fats are a type of unsaturated fat that
Artificial trans fats, often produced through partial hydrogenation of vegetable oils, have
Due to these risks, many countries, including the
Naturally occurring trans fats, however, are found in smaller amounts in dairy products and some meats, and researchers have debated whether they have the same harmful effects as industrial trans fats or may even have neutral or beneficial metabolic effects.
Now, a new analysis adds to growing evidence suggesting that naturally occurring trans fats may not carry the same cardiovascular risks
The findings, published in Nutrition Research, found no clear link between dairy-derived trans fats and an increased risk of heart disease, stroke, cardiovascular death, or type 2 diabetes.
The research team reviewed evidence from 22 studies involving participants from Europe, Canada, and the United States.
First, they reviewed 10 controlled dietary trials in which participants consumed dairy products with naturally elevated trans fat levels, then measured the effect on blood lipid biomarkers, which can help determine heart disease risk.
Across the trials, participants consumed between 1.3 and 13.2 grams (g) of dairy trans fats daily. The analysis found no meaningful differences in cholesterol or other blood lipid markers when compared with regular dairy consumption.
The team also reviewed 12 long-term observational studies that followed thousands of participants for years, in some cases more than 20 years. These studies measured levels of dairy-derived trans fats in the bloodstream and tracked health outcomes over time.
Again, the studies found no association between higher levels of dairy trans fats and increased risk of heart disease, stroke, cardiovascular death, or type 2 diabetes.
Michelle Routhenstein, MS, RD, CDCES, CDN, a cardiology dietitian and owner of Entirely Nourished, who was not involved in the study, was not surprised by the study findings.
“I was not surprised by these findings because previous research has shown that handmade trans fat behaves differently in the body than trans fats that naturally occur in dairy foods. We also have previous research suggesting that dairy foods have a pretty neutral effect on cardiovascular health,” Routhenstein told us.
“What is important to differentiate in this study is that it looked specifically at blood markers of dairy trans fats and still found no meaningful association with cardiovascular disease risk.”
– Michelle Routhenstein, MS, RD, CDCES, CDN
Although awareness around trans fats has increased significantly over the past two decades, particularly following global campaigns from the
Ian Givens, PhD, DFdSci(h.c.), one of the study’s lead authors and Professor of Nutrition at the University of Reading, told Medical News Today that many people still have misconceptions about dairy-derived trans fats, not knowing that, broadly speaking, there are two types.
Givens hopes the findings help clarify the differences between natural and artificial trans fats, which differ slightly in structure.
“I think that not all trans fatty acids are the same health-wise. Broadly, there are those industrially produced and those naturally produced by the microbes in an animal’s digestive system,” he explained.
“Trans fatty acids are defined as unsaturated fatty acids that contain a double bond in the so-called trans conformation. If the hydrogen atoms bonded to each of the carbons in this double bond are on the same side, this is called cis (generally natural),” the researcher detailed.
“If the two hydrogens are on opposite sides, this is called trans (industrial and natural), but natural trans differ from industrial mainly by the position of the double bond in the fatty acid chain,” continued Givens.
The researchers also add that the findings could also influence future food labeling policies, which often do not distinguish between industrial and naturally occurring trans fats.
“Put simply, the limits imposed on dietary trans-fat intake should be only based on the amounts of industrial trans not the total trans. There are now quick ways of identifying which are which,” Givens emphasized.
Although the findings may ease concerns around trans fats present in dairy products, it is still advisable to focus on overall dietary patterns rather than single nutrients.
Dietary guidance continues to encourage limiting industrial trans fats while consuming dairy in moderation as part of a balanced diet. The current Dietary Guidelines for Americans advises 3 servings of dairy per day as part of a 2,000-calorie dietary pattern, adjusting as necessary depending on individual caloric requirements.
Additionally, the researchers note that dairy products contain a complex mix of nutrients, including calcium, protein, and saturated fats, meaning their health effects cannot be explained by trans fat content alone.
While this review highlights the differences between natural and artificial trans fats, further research is still necessary to fully understand how naturally occurring trans fats interact with metabolism and cardiovascular health.
“If someone tolerates dairy well and enjoys it, it can fit into a heart-healthy diet when it complements an overall eating pattern rich in vegetables, fruits, whole grains, legumes, nuts, and seeds. If someone chooses to avoid dairy for ethical reasons, allergies, intolerances, or personal preferences, that is perfectly okay. Dairy is not required for a heart healthy diet. The key is ensuring they obtain the nutrients commonly provided by dairy, such as protein, calcium, potassium, and vitamin D, from other foods they tolerate and enjoy while maintaining a heart healthy eating pattern.
– Michelle Routhenstein, MS, RD, CDCES, CDN, MS, RD, CDCES, CDN
“When choosing dairy products, try to focus on minimally processed options such as plain yogurt, milk, and cheese, while limiting dairy high in added sugar or sodium,” Routhenstein advised.
“The full dietary pattern matters most since dairy is just one component of an overall eating pattern, and its impact on Health depends on what it is replacing and what the rest of the diet looks like,” she concluded.
