A new Canadian study suggests that eating full-fat dairy every day may not have the harmful effects many people expect.
Researchers found that three servings a day did not lead to worse body weight, body fat, cholesterol, or blood sugar control over 12 weeks.
The study was led by University of Toronto professor Harvey Anderson and included 74 adults with overweight or obesity. The findings were published in The Journal of Nutrition.
For decades, full-fat dairy has often been viewed with caution because it contains saturated fat. Saturated fat can raise LDL cholesterol in some people, and high LDL cholesterol is a well-established risk factor for heart disease.
Because of this, many dietary guidelines have encouraged people to choose low-fat or fat-free milk, yogurt, and other dairy products. The goal has been to lower saturated fat intake while still getting nutrients such as calcium and protein.
However, scientists have increasingly questioned whether the effects of whole foods can be predicted by looking at just one nutrient. Dairy contains protein, calcium, vitamin D, phosphorus, and many other compounds, all packaged together in a complex food structure.
In the new trial, researchers randomly placed participants into three groups. One group ate a low-dairy diet while also reducing calories, another ate three servings of dairy a day while keeping calories steady, and a third ate three servings of dairy without a calorie restriction.
All participants received advice based on Canada’s food guide. Those in the dairy groups were provided with full-fat dairy foods for the study.
After 12 weeks, the researchers did not find meaningful differences in weight gain, body composition, or blood lipid levels between the people eating more full-fat dairy and those in the low-dairy group. The higher-dairy groups also did not show clear signs of worsening insulin resistance.
That is important because insulin resistance can raise the risk of type 2 diabetes. If full-fat dairy had strongly harmed metabolic health, researchers might have expected blood sugar regulation to worsen during the trial.
Instead, participants consuming more dairy had some improvements in blood pressure. They also increased their intake of calcium, protein, and vitamin D, nutrients that are especially important for bone and muscle health.
The results add to a growing body of research suggesting that full-fat dairy may not behave in the body in the same way as isolated saturated fat. One explanation is known as the dairy matrix.
The dairy matrix refers to the physical and chemical structure of dairy foods. Milk, cheese, and yogurt contain fats, proteins, minerals, and other compounds that interact during digestion and may change how the body absorbs and uses them.
For example, dairy contains the proteins casein and whey. These proteins are combined with fat and minerals in ways that may affect digestion, fullness, and the movement of nutrients into the bloodstream.
This means that a food cannot always be judged only by its saturated fat content. Two foods with similar amounts of saturated fat may have different effects on cholesterol, blood pressure, or metabolism because the rest of their structure is different.
The study may be especially relevant for older adults. As people age, they often need fewer calories but still need enough protein, calcium, and vitamin D to help maintain muscle and bone strength.
Dairy can provide several of these nutrients in a relatively small amount of food. For older people who struggle to eat enough protein or maintain body weight, full-fat dairy may sometimes be a useful option.
However, the study has important limits. It included only 74 people and lasted 12 weeks, so it cannot show whether eating full-fat dairy for many years changes the risk of heart attack, stroke, diabetes, or other chronic diseases.
The researchers also studied adults with overweight or obesity, so the results may not apply equally to everyone. Individual responses to dairy can differ because of age, genetics, lactose tolerance, overall diet, and health conditions.
Another point worth noting is that the research received support from Dairy Research Cluster 3 under the Canadian Agricultural Partnership AgriScience Program and the Mitacs Accelerate program. Industry-related funding does not automatically make a study unreliable, but it is useful information when evaluating the evidence.
The randomized design is a strength because it reduces some of the differences that can confuse observational nutrition studies. Even so, larger and longer independent trials would provide stronger evidence about long-term cardiovascular safety.
Overall, the study does not prove that full-fat dairy is healthier than low-fat dairy. What it does suggest is that three daily servings did not worsen several major health measures over 12 weeks and may have improved nutrient intake and blood pressure.
The findings support a broader idea in nutrition science: whole foods should be judged by their total effects on health, not by a single nutrient alone. For many people, full-fat dairy may fit into a balanced diet without automatically being treated as an unhealthy choice.
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Source: University of Toronto.
