DUNEDIN, New Zealand — Here’s one more way to ensure stronger mental health: get your fruits and veggies from the produce section at the grocery store, and not the canned foods aisle. Researchers at the University of Otago in New Zealand found that raw fruit and vegetables have more a positive effect on mental health overall than canned, cooked, and processed produce.
Public Health campaigns in New Zealand and many developed countries push healthy quantities of fruits and vegetables, making no distinction between cooked and raw. But researchers found that the difference between how produce is prepared and consumed makes an even bigger difference for mental health outcomes.
“Our research has highlighted that the consumption of fruit and vegetables in their ‘unmodified’ state is more strongly associated with better mental health compared to cooked/canned/processed fruit and vegetables,” says lead author Kate Brookie, a psychology PhD student at the university, in a statement.
Co-author Dr. Tamlin Conner, a psychology senior lecturer, adds that the cooking and processing of raw fruits and vegetables can reduce natural nutrients.
“This likely limits the delivery of nutrients that are essential for optimal emotional functioning,” she says.
The researchers surveyed 400 young adults from New Zealand and the United States between the ages of 18 and 25. This age group was chosen because of their statistical preponderance for not consuming enough fruits and vegetables in their diets, and because this demographic is at a generally higher risk of mental health problems.
The researchers assessed study participants’ typical consumption levels of raw and cooked produce, along with positive and negative mental health and lifestyle variables for their demographic. Mental health outcomes were measured in terms of exercise, unhealthy diet choices, sleep regularity, chronic health conditions, socioeconomic status, ethnicity, and gender.
“Controlling for the covariates, raw fruit and vegetable consumption predicted lower levels of mental illness symptomology, such as depression, and improved levels of psychological wellbeing including positive mood, life satisfaction and flourishing. These mental health benefits were significantly reduced for cooked, canned, and processed fruits and vegetables,” says Conner.
As for which raw fruits and vegetables were found to have the strongest link to improved mental health, the researchers put together this top 10 list: Carrots, bananas, apples, dark leafy greens such as spinach, grapefruit, lettuce, citrus fruits, fresh berries, cucumber, and kiwifruit.
The study was published April 10, 2018 in Frontiers in Psychology.