(Medical Xpress)—New Zealand adolescents may need to increase their fruit and vegetable intake and reduce unhealthy options like sugary drinks and takeaways, to protect their mental health.
In a recent University of Auckland study, adolescents on a diet high in junk food had lower mental health scores, while on a diet high in healthy foods they had higher mental health scores.
The study aimed to examine the relationship between diet quality and self-reported emotional health in a large, ethnically diverse adolescent population in Auckland.
"This is part of a growing body of evidence suggesting that a diet of junk food might reduce mental well-being and that healthy food may improve mental well-being - although this will take clinical trials to demonstrate this effect with confidence," says Professor Boyd Swinburn who is an expert in population nutrition.
"Both parts are important and independent of each other, so it is important to not only increase fruit and vegetable intake, but also to reduce sugary drinks, takeaways, and unhealthy snacks," he says.
"Adolescence is a critical time for physical and psychological growth, and promoting mental health during this period is essential to the health and well-being of adolescents," says Professor Swinburn. "It is estimated that, each year, 20 percent of adolescents suffer from a mental health disorder."
Depression is the most prevalent mental health disorder, and is the primary contributor to disability in adolescence with significant negative physical, emotional and social consequences and continued implications for future quality of life.
"Successful physical and mental development during adolescence is dependent on adequate nutritional intake," he says. "But the evidence demonstrates that the diet quality of young people has deteriorated significantly in recent decades.
"There has been a dramatic increase in the amount of ultra-processed, unhealthy food in our food system and it is a very real question whether this is an important driver of the parallel rise in the prevalence of adolescent depression. Nutrition may have a vital role to play in mental health and the obesogenic food environment which is driving the obesity epidemic may also be partly responsible for the epidemic of depression," says Professor Swinburn. "Several studies in adult and adolescent populations have identified a significant relationship between diet quality and symptoms of depression.
"Our study identified a significant relationship between both healthy and unhealthy eating and mental health in a large, ethnically diverse population of adolescents in New Zealand," he says.
Professor Swinburn says it is widely recognized that a poor diet is associated with increased risk of diseases such as diabetes and heart disease, but the prevalence of many nutrition-related chronic conditions is low in adolescent populations as these diseases typically emerge during adulthood.
"However, there is a high prevalence of mental health disorders in this age group and
the prevalence of mental health symptoms appears to have increased in the past two decades," says Professor Swinburn.
"This increase parallels a global decline in the quality of adolescent diets (such as increased
intake of snacks, fast food, sweets and fried foods, and decreased intake of fruits and vegetables), suggesting that diet may have substantial immediate implications for the mental health and wellbeing of adolescents.
"Having a diet high in junk food or low in healthy food produced differences of 3.3 points and 5.4 on the rating scales we used," he says.
"To put that in perspective, others have found similar differences in emotional scores using the same scales between healthy adolescents and those with gastrointestinal disease (5.38 reduction), cardiac disease (5.55 reduction), end-stage renal disease (4.17 reduction), and obesity (3.80 reduction). The size of these potential effects of diet on mental health is certainly not trivial", says Professor Swinburn.
Provided by University of Auckland