A study in Switzerland found that adolescent athletes who consumed more protein in their diets had lower levels of depressive symptoms. The study was published in Psychology of Sport & Exercise.
The food we eat is comprised of different components. These include so-called macronutrients such as carbohydrates, proteins and fats, but also micronutrients such as vitamins and minerals. Macronutrients are nutrients that humans need a lot of, while micronutrients are needed in relatively small amounts. Both types of nutrients are essential for our health and well-being.
Appropriate intake of both macro- and micronutrients is related to our cognitive performance, mood, and mental health. Studies have shown that people with mental health issues often make poor food choices. This leads to inadequate diets. For example, people with severe mental illnesses were found to be prone to more excessive intake of food and to consuming lower quality diets compared to the general population.
Study author Markus Gerber and his colleagues noted that the relationship between diet and depressive symptoms has not yet been extensively studied and that mental health is of extreme importance to athletes. They conducted a 10-month study to explore whether the consumption of specific macronutrients (carbohydrates, proteins, fat) would predict the development of future depressive symptoms in adolescent elite athletes.
Participants in their study were 134 athletes, recruited from 3 Swiss Olympic Partner Schools in the German speaking part of Switzerland. These schools offer a special academic track to adolescent elite athletes, giving them an opportunity to combine elite sport and formal education.
Participants completed assessments twice – at the start of the study (August 2018) and a second time (at the end of June 2019). Participants were asked to create 3-day retrospective nutrition protocols in which they would list all food they consumed during a 3-day period. The 3-day period was set to include 2 weekdays and 1 day during weekend.
Research assistants visited all classes in participating schools and explained to students how to create this protocol. This protocol allowed researchers to calculate total energy intake and the amounts of specific macro- and micronutrients consumed. Participants also completed assessments of depressive symptoms and the researchers collected data on participants’ age, sex, body mass index, how many years they were involved in competitive sports, weekly hours of training and competition, nationality, and the educational track they were in.
Results showed that, at the start of the study, 13.9% of participants reported moderate-to-severe levels of depressive symptoms. At the second assessment, roughly a year later, this percentage was 11.4% (11 vs. 9 participants). Higher protein consumption was associated with lower levels of depressive symptoms at the second assessment. Levels of consumption of other types of macronutrients were not associated with depressive symptoms.
Additionally, researchers found that the total energy intake of participants, given their high physical activity levels, was below recommendations of the German, Austrian and Swiss Societies of Nutrition. The same was the case with the consumption of fat and of polyunsaturated fatty acids. Sugar consumption was above recommendations, while the intake of protein was adequate.
“The key finding of the present exploratory study is that higher protein consumption in adolescent athletes turned out to be a prospective predictor of lower depressive symptom severity at follow-up,” the researchers concluded.
The study contributes to the body of knowledge on relationships between diet and psychological factors. However, it also has limitations that need to be taken into account. Namely, dietary intake was assessed at only one point and for three days, meaning that diet quality changes over time could not be taken into account. Additionally, study design does not allow any cause-and-effect conclusions about relationships between studied factors.
The study, “Macronutrient intake as a prospective predictor of depressive symptom severity: An exploratory study with adolescent elite athletes”, was authored by Markus Gerber, Sarah Jakowski, Michael Kellmann, Robyn Cody, Basil Gygax, Sebastian Ludyga, Caspar Müller, Sven Ramseyer, and Johanna Beckmann.