Diet, exercise can improve teens' mental health
Depression and anxiety have been increasing among teenagers worldwide for many years, and the COVID-19 global pandemic only exacerbated the problem.
In October 2019, before anyone had heard of the SARS-CoV-2 virus, though, Peter Templeton, founder of the William Templeton Foundation for Young People's Mental Health and executive director at Institute for Manufacturing's Engage program in the Cambridge University Engineering Department, launched a wide-ranging, international, multi-disciplinary project intended to "innovate early interventions for depression in young people."
The project brought together stakeholders and specialists from students to educators, physicians, nutritionists, researchers and even insurance-company representatives to focus on "key aspects of the causal pathways of depression in young people," including genes and epigenetics, the microbiota-gut-brain axis, the hypothalamic-pituitary-adrenal (HPA) "stress" axis, diet and nutrition, exercise and sleep.
Among those invited to participate was Christopher Lowry, associate professor of integrative physiology at the University of Colorado Boulder.
"I was attracted to the project because my research is focused on stress-related psychiatric disorders," Lowry says. "My work on the microbiome-gut-brain axis was particularly why I was invited."
After collating ideas and information from a series of online workshops from November 2019 to January 2020, the project issued its 120-page final report, "Changing Hearts, Changing Minds: Evidence-based approaches to the prevention, diagnosis and treatment of depression in young people," in September.
One key finding is that diet, nutrition and exercise are among the most accessible and effective interventions to reduce depression in young people.
Most people intuit that diet and exercise improve the physical health of the human body. But Lowry and other researchers have been steadily building a body of evidence confirming that they also have a profound impact on mental health, through mechanisms as varied as the "gut-brain axis," epigenetics, the impact of hormones on stress, and sleep.
"Diet and nutrition is one of the main factors that influences mental-health outcomes," Lowry says. "But I don't think people have really processed how fundamentally important it is."
That may sound simple, Lowry says, but those interventions "are also potentially the hardest to implement because they involve lifestyle changes." In both the United States and United Kingdom, there are considerable obstacles to improving diet and nutrition among young people, as well as to getting them to exercise more.
For example, U.S. schools in the 1970s and '80s often provided homemade "hot lunches" and families sent children to school with a brown bag, but today's school cafeterias typically peddle food high in calories, salt, sugar and fat, and students may go off campus to eat fast food.
The answer, Lowry says, "is to reduce takeout foods, trans fats, high-sugar and ultra-processed foods and replace them with vegetables, fruits, nuts, seeds, healthy oils and fish ... Basically a Mediterranean diet."
Easier said than done, for a host of reasons.
First, it's no surprise that kids gravitate toward high-fat, high-sugar, high-salt food: The human body is evolutionarily primed to seek out such once-difficult-to-obtain nutrients.
But politics also has made it difficult to even offer healthy options in schools, Lowry says. In Britain, celebrity chef Jamie Oliver's effort to improve school nutrition met considerable resistance, while former First Lady Michelle Obama's campaign to reduce childhood obesity was criticized as an attack on liberty.
Additional challenges include poverty and families living in "food deserts" with limited access to affordable, nutritional food.
"If their only source of food is a Dollar Store, they have very little access to fresh fruit and vegetables," Lowry notes.
Meanwhile, Lowry's research suggests a radically altered approach to nutrition and diet. Since a healthy gut microbiome can reduce inflammatory disease and improve mental health, the best thing humans can do is increase the variety of organisms living in their bodies, he says.
"It's like a self-sustaining Amazon rainforest vs. a monoculture of wheat, where you have to input fertilizer and pesticide and fungicide, just to keep it alive," Lowry says. "Turns out the microbiome is like that: The more diversity you have, the consensus is, the healthier you are."
Eating a wide variety of plant-based food—up to 30 different kinds of plant, with up to 1,000 species of bacteria per plant, per week, Lowry says—can mean the ingestion of up to 30,000 species of bacteria that survive in specialized ecosystems on and in different plants.
"That understanding has completely changed the way I think about feeding my own children. I'll give them one or two small carrots, one or two blueberries, and so on, very small proportions, very high diversity of foods. It would be great if you could buy a pack of 30 different vegetables at the grocery store, take it home and graze on all those different plants. ... We need a little 'hunter-gatherer' pack, but no one's done that yet."
Getting kids to exercise more to improve their mental health faces implementation challenges, as well. Just 24% of children 6 to 17 years of age participate in the recommended 60 minutes of physical activity every day, according to the U.S. Centers for Disease Control (CDC), and levels of activity decline continually as they age.
In decades past, American schools placed greater emphasis on challenging physical education, requiring all students to do everything from run a timed mile once a month to clambering up a two-story rope and do calisthenics. But where 41% of high-school students participated in physical education activities in 1991, only 25% did as of 2015, and just 3.7% of K–12 schools require daily physical education, according to the CDC.
And increasing obesity in children—almost one out of five children is considered clinically obese, the CDC reports—"further impairs their ability to engage in meaningful exercise," creating a downward spiral.
Despite the challenges moving forward, Lowry applauds the innovative process that led to the report. Based on engineering principles and tested management techniques, it brought together participants from widely varying fields, disciplines and backgrounds to collaborate on identifying the problem and potential interventions.
"As scientists, one of the criticisms we often hear is that we work in siloes—a narrow focus, without really interacting with other scientists," he says. "But this particular project was good at breaking down those siloes. ... It's rare to be able to engage with a process that has such a broad spectrum of participants."