For more than half a century, there has been an assumption that fatty foods, particularly those containing saturated fats, are detrimental to health and should be limited as much as possible. As a result, the U.S. Dietary Guidelines for Americans have urged consumers to reduce fat intake for 35 years, recommending low-fat and no-fat dairy products. During session 215, “Fat Is Back: Emerging Science Around Health, Nutrition, and Application,” presenters dispelled the idea that dairy fat is not beneficial to human health.
Moises Torres-Gonzalez of the National Dairy Council said that the fight against fat began with the “Seven Countries Study” in the 1950s and 1960s, which associated saturated fat with cardiovascular disease. This study gave rise to the paradigm that saturated fat raises LDL cholesterol and elevated LDL cholesterol is associated with increased risk of heart disease, so saturated fat must cause cardiovascular disease. Health authorities worldwide therefore began recommending low-fat diets and reduced-fat dairy products because dairy foods are high in saturated fat. However, since the emergence of low-fat foods and low-fat diets, there has been a steady rise in the incidence of cardiovascular disease in the United States and around the world, Torres-Gonzalez said. While overconsumption of food in general is likely a factor contributing to the increased incidence of cardiovascular disease, Torres-Gonzalez said that low-fat diets may also be playing a role. Emerging research on dairy fats and health appears to support this line of thinking.
Jana Kraft of the University of Vermont discussed some of that emerging research. Focusing on the relationship between dairy fats and type 2 diabetes, Kraft said that type 2 diabetes is a growing public health concerns as more than 30 million Americans have been diagnosed with the disease. People with type 2 diabetes are at higher risk of stroke; blindness; kidney disease; heart disease; and loss of toes, feet, or legs. Type 2 diabetes is largely preventable, Kraft said, by keeping weight under control, being physically active, and eating a nutritious balanced diet. For years, health authorities have been saying that low-fat and fat-free dairy products are part of a nutritious balanced diet. She said that highly reliable scientific evidence from meta-analyses, systematic reviews, and randomized, controlled clinical trials proves that this is not true.
According to Kraft, a recent systematic review of studies on dairy and health found that total dairy is associated with a decreased risk of type 2 diabetes, low-fat dairy is associated with a decreased risk of type 2 diabetes, and high-fat dairy is not associated with an increased risk of type 2 diabetes. Some systematic reviews have found that total dairy has an inverse association with type 2 diabetes, low-fat dairy has an inverse association with type 2 diabetes, and high-fat dairy has a neutral relationship with type 2 diabetes. Another systematic review found that higher levels of the sum of dairy fat biomarkers were associated with a 30% lower risk of developing type 2 diabetes. Although there are not a lot of randomized clinical trials on the effect of dairy on type 2 diabetes, Kraft said that one clinical trial indicates that dairy fat has neutral or protective effects on type 2 diabetes. More randomized clinical trials are needed, but in general, the evidence is clear: total dairy intake lowers the risk of type 2 diabetes, low-fat dairy lowers the risk of type 2 diabetes, and full-fat dairy has no effect on type 2 diabetes.
Ravin Gnanasambandam of Land O’Lakes said that besides dairy fat having health benefits, it also has great functionality. He defines functionality as a property of a substance or material that affects its utilization and physicochemical property but not its nutritional property. Dairy fat consists of several types of triglycerides with broad melting points. Moreover, dairy fats, which can be either solid or liquid, can break down structures, change texture, deliver flavor, serve as a lubricant, and induce satiety. In addition, more than 200 flavor compounds have been identified in dairy fat. Milkfat contains short-chain fatty acids that contribute to its flavor. Milkfat is a complex edible fat and is usually minimally processed; no other fat has as much functionality as dairy fat, Gnanasambandam said.
The speakers all agreed that the quality of one’s diet is more important than single nutrients, so whole fat dairy foods can be part of a healthy eating style. Indeed, fat is back.