Debbie Nicholson

Since childhood, our mothers have always told us to eat our fruit and vegetables for good health. It appears they may have been on to something, or at least might have known what science does. According to new research from the University of Otago in New Zealand, consuming more fruits and veggies makes young adults calmer, happier and more energetic.

Dr Tamlin Conner, PhD, researcher and assistant professor, Dr. Caroline Horwath, PhD, and Bonnie White from the University of Otago, Department of Human Nutrition, examined the role of daily stress and mood on eating behavior r in a student population and to examine the moderating effect of trait characteristics on these associations according to the studies abstract.

For the study, 288 undergraduate students from the university completed a questionnaire which provided details of their gender, ethnicity, weight and height.

Following the questionnaire the students (average age of 20) completed a daily dairy survey for 21 days. Students accessed a secure webpage each day and reported the type and intensity of their daily stress, mood, and daily eating behaviors that included number of servings eaten of fruit (excluding fruit juice and dried fruit), vegetables (excluding juices), and several categories of unhealthy foods like biscuits/cookies, potato crisps, and cakes/muffins.

The results showed on days when students reported a greater positive effect they also reported eating more fruits and vegetables. “They reported feeling calmer, happier and more energetic than they normally did," said Dr. Conner.

On the other hand, when students reported a greater negative effect they also reported consuming more unhealthy foods like corn chips and consuming less fruit. The researchers reported that this was driven by feelings of sadness and depression.

In order to find out which came first; feeling positive or consuming healthy foods, the team ran additional analyses and found that eating fruits and vegetables predicted improvements in positive mood the next day, suggesting that healthy foods may improve mood. These findings held regardless of the BMI of individuals.

The research also revealed ego-threatening and interpersonal stress were associated with consuming more food, in particular ego-threatening stress was associated with consuming more fruits and vegetables , and interpersonal stress was associated with consuming more chocolate-coated and cream-filled biscuits .

Dr. Conner stated, “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. One serving of fruit or vegetables is approximately the size that could fit in your palm, or half a cup. My co-author Bonnie White suggests that this can be done by making half your plate at each meal vegetables and snacking on whole fruit like apples.”

In their conclusion the researchers write, “The adverse association between ego-threatening and interpersonal stress or negative affect and unhealthy eating behavior is consistent with previous research. A unique finding was the link between positive affect and higher fruit and vegetable consumption. Individuals with a high BMI may be at risk of unhealthy eating behavior’s under stress and negative affect.”

Dr. Conner adds that while this research shows a promising connection between healthy foods and healthy moods, further research is necessary and the authors recommend the development of randomized control trials evaluating the influence of high fruit and vegetable intake on mood and well-being.


Slideshow: Foods to boost mood

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