A study analyzing data from nearly 46,000 people finds that one dietary approach doesn’t fit all when it comes to reducing symptoms of depression.
How diet affects mood is a rich area of research lately, especially with interest piquing in high-protein diets, flavors of the Mediterranean Diet, and a grab-bag of “whole” diets. But whether one diet works decisively better than the others remains an open question.
The latest study was a meta-analysis, meaning it analyzed data from several randomized and controlled studies focused on similar questions. Researchers chose 16 studies to include in the analysis, all looking for dietary links to mental health improvements, specifically a decrease in depression and anxiety symptoms and cases in which the two conditions overlap (aka, comorbidity).
The data covered multiple diets, “including those primarily aiming to decrease the intake of unhealthy foods, improve nutrient intake, and/or those designed to restrict calorie intake to induce weight-loss.” Diets that excluded entire food groups or emphasized one food above others (like eating fish at every meal) were purposefully left out of the analysis.
The results showed that all types of dietary approaches had equal effects on reducing depression symptoms, but anxiety symptoms weren’t significantly improved.
“Adopting a healthier diet can boost peoples’ mood,” said lead study author Joseph Firth, an Honorary Research Fellow at The University of Manchester. “However, it has no clear effects on anxiety.”
The researchers describe the results as “good news” and evidence that “highly-specific or specialized diets are unnecessary for the average individual.”
“Instead, just making simple changes is equally beneficial for mental health,” added Dr. Firth. “In particular, eating more nutrient-dense meals which are high in fiber and vegetables, while cutting back on fast-foods and refined sugars appears to be sufficient for avoiding the potentially negative psychological effects of a ‘junk food’ diet.”
The research also showed that diet combined with exercise produced better results than diet alone, and that “studies with female samples observed significantly greater benefits from dietary interventions, for symptoms of both depression and anxiety.”
While it’s increasingly well-established that diet combined with exercise produces better mental health outcomes, the difference in results for women and men is a mystery.
“We’re not yet sure why some of our data showed significantly greater benefits from diets for women,” said Firth, adding that more research is needed to address that and other murky issues this study couldn’t address.
The researchers noted that while both clinical and non-clinical cases of depression were included in the studies, the most significant benefits were linked to improvements in non-clinical cases. “Further research is still required to examine the effects of dietary interventions in people with clinically-diagnosed psychiatric conditions,” added Firth in a press statement.
Overall, though, these results contribute to what’s becoming a common scientific refrain – improving diet can boost mood, and improving diet along with exercise can boost it even more.