Full-fat dairy products can be part of a healthy diet, according to a study led by University of Toronto professor Harvey Anderson reported by ScienceDaily. The research adds to a growing body of evidence on the benefits of dairy.
Over 12 weeks, 74 adults consumed varying amounts of dairy as part of different diets. The researchers found that eating three servings of full-fat dairy a day had no negative effect on body weight, body composition, energy metabolism or blood lipid levels.
ScienceDaily noted that people are often encouraged to choose low-fat or fat-free dairy to reduce saturated fat intake, but Anderson and his colleagues said these concerns are not supported by the evidence. Human studies have found no link between full-fat dairy consumption and harmful health outcomes, and some studies have even shown a positive or protective effect.
How the experiment was run
The 74 adults, who were overweight or obese, were randomly assigned to one of three diet groups: a low-dairy, calorie-restricted diet; a neutral-energy-balance diet including three servings of dairy a day; and an unrestricted diet that also included three daily servings of dairy. All participants were advised to follow Canada's food guide, and those in the dairy groups received full-fat products.
After 12 weeks, the researchers found no significant differences in weight gain, body composition or cholesterol levels between the low-dairy group and those eating three servings a day. However, participants who ate more dairy showed improved blood pressure readings and higher intakes of calcium, protein and vitamin D. Anderson said those who consumed three servings of dairy showed no adverse cholesterol or blood lipid levels, and no signs of insulin resistance.
The dairy matrix hypothesis
ScienceDaily said the gap between the expected harm of saturated fat and the neutral or beneficial effects seen in some dairy studies may be explained by what researchers call the "dairy matrix hypothesis," the idea that the physical structure of dairy affects how its nutrients are digested and absorbed. Anderson explained that dairy contains two proteins, casein and whey, bound together by fat and mixed with nutrients. He said this structure allows the nutrients in dairy to enter the body gradually.
