Eating more fruit and fewer savory snacks predicts better mental health, study finds

New findings from psychology offer evidence that the foods we eat have a direct influence on our mental health. The study, published in the British Journal of Nutrition, found that eating more fruit predicted fewer symptoms of depression and greater psychological well-being, while eating more salty snacks predicted greater anxiety.

In recent years, scientists have begun to consider whether modifying diet might offer a path to improving psychological health. This idea comes on the heels of evidence linking consumption of nutrient-dense foods (eg, fruits and vegetables) with fewer mental health problems, and consumption of nutrient-poor foods (eg, sweets, salty snacks) with worse stress, anxiety and depression.

It’s not clear why diet might affect mental health, but study author Nicola-Jayne Tuck and her team say it may have to do with how nutrients affect our cognitive processes. Previous studies have suggested that a nutrient-poor diet negatively impacts cognitive function, while a nutrient-rich diet improves it. And cognitive deficits, such as reduced inhibitory control and cognitive failures, have been associated with poorer mental health.

Tuck and colleagues conducted a study to explore whether diet could influence mental health through its impact on cognition, while also investigating the impact of both frequency and amount of fruit and vegetable consumption.

A nationally representative sample of 428 UK residents completed an online survey that assessed their dietary habits, psychological health and cognitive function. Participants were asked to indicate how often they ate fruits, vegetables, sweet snacks (eg, cakes, cookies), and salty snacks (eg, potato chips) per day during the past month, and how many servings of fruits and vegetables ate per day. day. They also completed assessments for depression, anxiety, stress, and psychological well-being. To control for possible covariates, participants completed certain health-related measures that included smoking, alcohol, and exercise habits.

In addition, subjects completed a self-report cognitive failure questionnaire that assessed “mental lapses related to attention, memory, perception, and action on everyday tasks” in the past 6 months (eg, forgetting appointments, dropping things ). Participants then completed the Stop-Signal task as a behavioral measure of cognitive control.

Results revealed that, after controlling for covariates, frequency of fruit consumption (but not quantity of fruit consumption) positively predicted psychological well-being and negatively predicted depression. While additional experimental data is needed, the study authors speculate that “how often we eat fruit may be more important than the total amount we eat.”

Consumption of salty snacks (but not sweet snacks) positively predicted anxiety. This is in line with previous research suggesting that salty food and fast food can increase anxiety. Notably, the study was cross-sectional, so the direction of this relationship is unclear. It could be that people with higher stress and anxiety eat more nutrient-poor foods as a coping strategy.

The results further revealed that the link between salty snacks and mental health was mediated by cognitive impairments. In other words, participants who ate salty snacks reported more cognitive failure and, in turn, more symptoms of depression, anxiety, and stress, and less well-being. Since animal studies have suggested that saturated fat may reduce memory function, it’s possible that salty snacks high in saturated fat may affect memory and, in turn, mental health.

Interestingly, frequency of vegetable intake did not affect mental health after controlling for covariates. The researchers say this may be because the vegetables people eat are often canned and cooked, which could limit nutrient absorption. Fruits, on the other hand, tend to be eaten raw.

Overall, the findings suggest that adjusting intake of nutrient-poor (processed) and nutrient-rich (unprocessed) foods may help protect mental health. “Further work is now required to establish causality,” Tuck and colleagues say, “and to determine whether these may represent modifiable dietary goals that may directly (and indirectly) influence our psychological health.”

The study, “The frequency of consumption of fruits and salty snacks predicts psychological health; selective mediation through cognitive failures”, was written by Nicola-Jayne Tuck, Claire V. Farrow and Jason Michael Thomas.