Their study, which was funded by the Dutch Dairy Foundation, followed more than 120,000 older adults for a decade.
It showed no relationship between men’s dairy intake and their risk of dying during the study period. Among women, meanwhile, a high intake of dairy fat — from butter or other full-fat dairy — was linked to a small increase in deaths, particularly those due to heart disease.
In contrast, eating full-fat sour dairy products, including yogurt and sour cream, was tied to a slight decrease in deaths among both men and women.
None of those relationships prove that dairy products were the reason for the higher or lower risks, however. And even if they were, the effects were tiny, the researchers say.
So the findings offer little reason for people to either boost or lower their dairy intake, lead researcher Dr. R. Alexandra Goldbohm, of TNO Quality of Life in Leiden, the Netherlands, said in an e-mail.
The possible role of dairy products in the risks of heart disease and other chronic diseases has not been straightforward.
On one hand, full-fat dairy is a source of saturated fat, which could raise cholesterol and contribute to heart disease. And some studies, though not all, have linked a high intake of full-fat dairy to increased risks of certain cancers, like prostate cancer.
On the other hand, recent studies have suggested that the calcium, protein, and unsaturated fats in dairy may have health benefits ranging from lower blood pressure to better weight control.
But at least when it comes to longevity, these latest findings suggest that dairy products “are neither very harmful nor very beneficial,” Goldbohm’s team writes in the American Journal of Clinical Nutrition.
The findings are based on 120,852 adults ages 55 to 69 who were followed for 10 years. At the outset, they all completed detailed dietary questionnaires.
Over the next decade, just over 16,000 study participants died. Among men, there was no clear link between their intake of various types of dairy and their risk of dying during the follow-up.
The same was true for women when looking at their overall dairy intake. But for each 10-gram increase in butter intake per day (about one-third of an ounce), the odds of dying during the study period inched up 4 percent. Similar increases were seen when the researchers looked at fat from any dairy source.
That was with factors like weight, overall diet, and exercise habits taken into account.
Meanwhile, among the 692 women who died of heart disease, the risk crept up in tandem with butter intake.
It’s not clear why the findings were different for men and women, Goldbohm said. But some other research, she noted, has suggested that men and women may process saturated fats differently.
In contrast to the findings on butter and overall dairy fat, full-fat fermented dairy products — including yogurt, sour cream, and a type of fresh cheese called quark — were linked to a small decrease in death risk for both men and women.
For each 100 milliliter increase per day (a little more than three ounces), the risk dipped by about 8 percent.
Goldbohm said that more research is needed to confirm any protective effect of fermented dairy products.
One theory, she noted, is that certain proteins in fermented dairy called tripeptides may help lower blood pressure. But studies have come to conflicting conclusions as to whether that is true.
In the United States, the government’s recently updated dietary guidelines call on people to opt for fat-free or low-fat varieties of milk, yogurt, and cheese, and to replace butter and other sources of saturated fat with the heart-healthy unsaturated fats found in vegetable oils and fatty fish like salmon and mackerel.