Researchers at the University of Otago in New Zealand sought to investigate the relationship between day-to-day emotions and food consumption, by having 281 young adults log a daily food diary for 21 consecutive days, while also rating their mood.
The results showed a strong day-to-day relationship between more positive mood and higher fruit and vegetable consumption, but not other foods.
"On days when people ate more fruits and vegetables, they reported feeling calmer, happier and more energetic than they normally did," said researcher Dr Tamlin Conner.
She added that eating fruits and vegetables were linked to improvements in mood the following day, suggesting that consuption affects mood, not the other way round.
"After further analysis we demonstrated that young people would need to consume approximately seven to eight total servings of fruits and vegetables per day to notice a meaningful positive change," Conner said. But she also urged further research to back up the findings.
The results are published in the British Journal of Health Psychology.