July 18, 2022 -- People who frequently eat fruit are less likely to report symptoms of depression, according to a new study,  which found that how often people ate fruit was more important than how much they ate.

While good news for fruit-lovers, the study also people who eat energy-dense and nutrient-poor processed savory snacks had worse mental health.

For the research, a team from the Aston University in Birmingham, England, conducted an online survey of 428 adults from across the United Kingdom who answered a range of questions about their diet, mental health, and everyday cognitive ability. The participants were 53% female, 90% White, with an average age of 39.7 years and no major health problems, food allergies or eating disorders. Average BMI was 26.0, 53% were normal weight, and 86% rated their general health as good to excellent.

They were asked about how much fruit, vegetables, sweet and savory snacks (such as chips, cookies, cakes, chocolate, and sweets) they ate, and about symptoms of anxiety, stress and depression. Other questions aimed to measure overall mental wellbeing and “everyday mental lapses” – such as forgetting where their left something, or why they’d gone into a particular room, and being unable to remember someone's name even though it was “on the tip of their tongue”.

The results, published in the British Journal of Nutrition, showed:

  • The more fruit and vegetables someone ate was tied to lower depression risks.
  • How often and how much fruit someone ate improved mental health scores. Eating vegetables often did not appear to affect mental health.
  • Eating more sweet and savory snacks increased anxiety risks.
  • Eating savory snacks was tied to higher stress risks.

Other studies found a connection between fruit and vegetables and mental health, but few have looked at fruit and vegetables separately, lead author, PhD student Nicola-Jayne Tuck, a postgraduate researcher in the School of Psychology at Aston University, says.

"Both fruit and vegetables are rich in antioxidants, fiber and essential micronutrients, which promote optimal brain function, but these nutrients can be lost during cooking,” Tuck says. “As we are more likely to eat fruit raw, this could potentially explain its stronger influence on our psychological health."

Savory Snacks Increase Mental Lapses and Lower Wellbeing

The team also found that people who frequently snacked on nutrient-poor savory foods were more likely to experience cognitive failures as well as to report lower mental wellbeing. A greater number of lapses was associated with higher reported symptoms of anxiety, stress and depression, and lower mental wellbeing scores.

By contrast, there was no link between these everyday memory lapses and fruit and vegetable consumption or sweet snacks, suggesting "a unique relationship" between nutrient-poor savory snacks, everyday mental lapses, and psychological health.

It has been noted before that high energy, low micronutrient foods may reduce optimal brain function, , leading to poorer psychological health. Saturated fat and sugar decrease cognitive performance, while fruits and vegetables enhances cognition.

Frequent cognitive failures are known to be significant predictors of anxiety and depression symptoms, and have been associated with increased perceived stress and sadness. In addition, reduced inhibitory control (reaching for the chips bag) is a risk factor for depression. "It’s really important to address the complexity of food choices and mental health,” Aisling Pigott, a registered dietitian and spokesperson for the British Dietetic Association, says. “We know that there are many barriers to a healthy diet, including mental health, socio-economic status and education.

"People eating more fruit and vegetables are likely to be having a nutrient rich diet, with plenty of vitamins, minerals and fiber. They will be less likely to be micronutrient deficient.”

However, they are also more likely to be financially secure in order to afford those fruit and vegetables, Pigott says.

“Therefore it is much more complex than a direct cause/effect model.”