Yogurt has had a banner few years as research continues to support its many health benefits, including the US Food and Drug Administration's recent support of the qualified health claim that yogurt in the diet may reduce the risk of type 2 diabetes. A recent randomized control crossover study in the Journal of Dairy Science is adding to the list of dairy's health accomplishments, demonstrating that a dairy-based, protein-rich breakfast not only keeps you fuller--compared with a carb-rich meal or skipping breakfast entirely--it also helps to boost concentration in the critical first hours of the day.
"Breakfast is the most frequently skipped meal in the western part of the world," explained the study's lead investigator, Mette Hansen, PhD, associate professor in the Department of Public Health at Aarhus University in Aarhus, Denmark. "Epidemiological studies clearly show that skipping breakfast is associated with a higher risk of [being] overweight, and other intervention studies [note that] several components in the diet--low contents of protein, fiber, and calcium--may have a detrimental effect on weight regulation. This suggested that the content of the breakfast may influence the health impact of the breakfast meal." In light of this, the researchers were curious to understand whether a high-protein, low-carbohydrate breakfast would lower calorie intake later in the day and help people feel fuller for longer compared with skipping breakfast or eating a high-carbohydrate meal.
Hansen and her team, therefore, set out to test their theory through a randomized trial following 30 young women for three test days separated by at least two days. The day before each test, the women's physical activity levels and diets were standardized. Participants aged 18 to 30 had body mass index (BMI) scores higher than 25, classifying them as overweight to obese.
During the study, the participants either consumed a protein-rich breakfast of skyr yogurt and oats or a low-protein, high-carbohydrate meal of whole grain bread with raspberry jam and apple juice. Both meals had matching energy content and density and the same amount of dietary fiber and fat. The control group skipped breakfast entirely (save for a glass of water). "All three of these options reflect common and commercially available breakfast choices here in Denmark," explained Hansen.
After breakfast, the team calculated the energy intake of participants at lunch and throughout the rest of the day and rated their appetite between meals. Blood samples were taken between breakfast and lunch to test for appetite-regulating gut hormones, insulin, and glucose. Finally, the team measured the participants' performance in a concentration test two-and-a-half hours after breakfast.
The study results revealed that the young women participating felt more satiated and less hungry after a dairy-based, high-protein, low-carbohydrate breakfast compared with a low-protein, high-carbohydrate breakfast or no breakfast. "However, this was not translated significantly to their gut hormones or overall calorie intake for the day," explained Hansen, "suggesting that a high-protein breakfast might not be a weight-loss solution on its own."
Interestingly, the breakfast choices affected cognition. After eating the high-protein yogurt, participants showed a boost in their concentration test scores compared with those who skipped breakfast. This cognitive improvement was not seen in those who ate toast with jam and juice. "To the best of our knowledge, the cognitive effects of acute protein intake have not been previously investigated in this population of young women," said Hansen.
The study team was quick to point out that these results could benefit from additional research to understand how breakfast choices impact health over time and in more diverse populations.
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