For many years, people were told to choose low-fat or fat-free dairy products because full-fat dairy contains saturated fat, which was believed to increase the risk of heart disease.
As a result, many families switched to low-fat milk, yogurt, and cheese.
However, in recent years scientists have begun to question whether the picture is really that simple.
A new Canadian study suggests that full-fat dairy foods may not be as harmful as once believed when they are eaten as part of a balanced diet.
The research was led by Professor Harvey Anderson from the University of Toronto and was published in the Journal of Nutrition. The study examined whether eating three servings of full-fat dairy each day would affect body weight, body fat, metabolism, cholesterol, and other measures of health.
The researchers recruited 74 adults who were overweight or living with obesity. Participants were randomly assigned to one of three eating plans. One group followed a lower-dairy diet while reducing calories.
A second group ate three servings of full-fat dairy each day while keeping their calorie intake about the same. A third group also consumed three daily servings of full-fat dairy without strict calorie limits. Everyone was encouraged to follow Canada’s Food Guide so the overall diet remained balanced.
After 12 weeks, the scientists compared the health results of the different groups. They found no meaningful differences in body weight, body composition, cholesterol levels, blood fats, or energy metabolism between people eating less dairy and those consuming three servings of full-fat dairy every day. Importantly, the higher dairy intake did not increase signs of insulin resistance.
The researchers also found several possible benefits. People eating more dairy consumed higher amounts of calcium, vitamin D, and protein, three nutrients that are important for healthy bones, muscles, and many body functions. They also experienced improvements in blood pressure, suggesting that dairy foods may provide benefits beyond simply supplying calories.
Professor Anderson says these findings add to growing evidence that foods should be judged as complete foods rather than by one nutrient alone. Dairy products contain protein, vitamins, minerals, healthy bacteria in some products, and a unique physical structure known as the dairy matrix.
Scientists believe this structure changes the way nutrients are digested and absorbed, which may explain why dairy foods sometimes have different health effects than expected from looking only at saturated fat.
The study is especially relevant for older adults. Many older people need more protein but eat less food because their energy needs decline with age. Full-fat dairy products can provide protein, calcium, vitamin D, and other nutrients in relatively small portions, making them a practical choice for maintaining muscle and bone health.
The research does have limitations. It involved only 74 participants and lasted 12 weeks, so it cannot answer questions about very long-term health outcomes. Larger studies that continue for several years are still needed.
Overall, this study suggests that moderate amounts of full-fat dairy can fit into a healthy eating pattern without harming weight, cholesterol, or metabolism.
While it does not prove that everyone should switch to full-fat dairy, it supports the idea that nutrition is more complex than simply avoiding one nutrient. Looking at whole foods instead of individual ingredients may lead to more practical dietary advice in the future.
The findings were published in the Journal of Nutrition.
The study is well designed because participants were randomly assigned to different diets, which reduces bias. However, the relatively small sample size and short duration mean the findings should be confirmed in larger long-term trials.
Even so, the results add to growing evidence that moderate consumption of full-fat dairy may be safe for many healthy adults as part of an overall balanced diet.
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