Dairy products like cheese, butter, and whole milk contain saturated fats. Past research has shown that diets with high levels of saturated fats can increase the risk of cardiovascular disease, such as heart disease and stroke. Saturated fats have also been linked to increased mortality rates. Understanding the health effects of dairy fats is challenging because dairy products are complex. They contain many nutrients like calcium that have health benefits.

When we digest dairy foods, the fatty acids from the food travel through the bloodstream. These fatty acids can be used in research studies as biomarkers of dairy fat consumption.

A research team led by Dr. Marcia C. de Oliveira Otto at the University of Texas Health Science Center at Houston and Dr. Dariush Mozaffarian of Tufts University explored the connections between dairy fatty acids and cardiovascular disease and death. Their work was funded in part by NIH’s National Heart, Lung, and Blood Institute (NHLBI) and other NIH components.

The study included nearly 3,000 adults in California, Maryland, North Carolina, or Pennsylvania who were older than 65 and free of heart disease at the start of the study. The participants had physical exams and lab tests, and answered questionnaires. The team assessed three fatty acids that reflect dairy intake (pentadecanoic, heptadecanoic, and trans-palmitoleic fatty acids) in blood samples obtained at the start, at 6 years, and at 13 years. The results appeared online in the American Journal of Clinical Nutrition on July 11, 2018.

More than 2,400 people died over the course of the 22-year study period. The researchers accounted for demographic, lifestyle, cardiovascular, and dietary factors. They found no significant links between overall risk of death and long-term exposure to the three dairy fatty acids.

Next, the team investigated specific causes of death. More than 800 people died from cardiovascular causes, such as heart attacks and strokes. About 1,600 deaths were from other causes, such as cancer and infection. The team noted a lower risk of death from cardiovascular disease—in particular, stroke—for those with higher levels of heptadecanoic acid. On the other hand, those with higher levels of heptadecanoic acid had a higher risk of death for non-cardiovascular causes. The other two dairy fatty acids did not have significant links to cardiovascular or noncardiovascular deaths.

The findings support a growing body of evidence that suggests dairy fat does not increase the risk of heart disease or overall mortality in older adults.

“Our results highlight the need to revisit current dietary guidance on whole fat dairy foods, which are rich sources of nutrients such as calcium and potassium,” Otto says.

—Geri Piazza