The de-stress diet: Improve your mood with fruits and veggies

There’s growing evidence that certain foods bring about better moods

If you mention that grey skies make you sad you won’t get much pushback – many believe that rainy days bring about miserable moods and know at least one person who’s predictably affected – yet there’s genuine skepticism about food’s effect on our mental wellbeing.

Nutritional psychiatry is still an emerging field.

There’s growing evidence, however, that certain foods bring about better moods, and that other foods can bring you down.

Several studies have shown that a healthy diet, rich in fruits and vegetables, may impact mental health and is associated with lower rates of depression. Besides numerous studies that show a link between eating fruits and veggies and psychological benefits, there are also studies that actually put it to the test: a study of 171 young adults who usually don’t eat their 5-a-day were assigned to either start doing so or continue as usual. After 14 days the participants on the fruit and vegetable boosted diet reported greater psychological wellbeing.

De-stress with salad?

A new study in the journal Clinical Nutrition examines the connection between eating fruits and vegetables, and perceived stress levels. The researchers looked at a large population of more than 8600 25-91 year olds from the Australian Diabetes, Obesity and Lifestyle cohort. Diet and perceived stress were assessed by validated questionnaires. The stress questions were things like: “you feel rested”,“you feel that too many demands are made on you”, and “you are irritable or grouchy” on a sliding scale. 

And the results: Those eating the most fruits and vegetables (more than 470 grams a day, about 16 ounces, which is close to the recommended minimum of 5 servings a day) felt less stressed than those who ate the lower end of fruits and veggies (less than 240 grams or 8 ounces a day). These findings held after adjusting for confounding factors such as exercise, smoking and caloric intake. 

An inverse relationship between plant-based foods and stress has been shown in other studies. A recent systematic review of studies in the journal Nutrients, which included 61 studies, and looked at fruit and vegetable intake and a whole array of psychological symptoms, from depression to general mental wellbeing, quality of sleep, stress, nervousness and happiness, concludes that eating 5-a-day “seems to have a positive influence on mental health, as stated in the vast majority of the included studies.”

The inflammatory connection

This association doesn’t prove causality. The connection is plausible, though, and could be explained by the fact that fruits and vegetables contain antioxidant phytochemicals that reduce inflammation and cellular oxidative stress.

The connection between inflammatory foods and mood disorders was examined in a recent meta-analysis in Public Health Nutrition, which included four studies and about 50,000 people, looking to see if the inflammatory profile of their diet is linked with developing depression.

The diet was scored using the Dietary Inflammatory Index, an index based on thousands of scientific articles, which enabled scoring most foods and nutrients.

The study found that a pro-inflammatory diet (a diet low on fruits and veggies, high on highly processed food, meat, refined grain, desserts and sugar) was associated with a higher incidence of depression, and that people eating diets with the highest inflammatory score had a 23 percent higher risk of becoming depressed.

As mentioned above, mental nutrition research is relatively new. The 5-a-day fruit and vegetable recommendation is already exhaustingly verified and established as a way to support health and wellbeing, so the mental-health benefits, if they pan out, are just another added bonus.

Dr. Ayala