Kiwifruit can rapidly improve mental health, study suggests

Kiwifruit has proven to be a powerful mood enhancer, and new research from the University of Otago has shown just how fast its effects can be. In a study published in British Journal of Nutritionresearchers found that the hairy fruit improved vitality and mood in just four days.

Co-author Professor Tamlyn Connor from the Department of Psychology says the findings provide a tangible and accessible way for people to support their mental wellbeing.

“It’s great for people to know that small changes to their diet, like adding kiwis, can change the way they feel every day.”

Vitamin C intake is associated with improved mood, vitality, well-being and lower depression, while vitamin C deficiency is associated with higher depression and cognitive impairment.

However, Professor Connor says limited research has assessed how quickly improvements in mood occur after introducing vitamin C supplements or whole food sources.

The researchers aimed to fill this gap with an eight-week dietary intervention in 155 adults with low vitamin C.

Participants took a daily vitamin C supplement, a placebo, or two kiwi fruits. They then report their vitality, mood, flourishing, sleep quality, sleep quantity and physical activity using smartphone surveys.

The researchers found that kiwifruit supplementation improved vitality and mood within four days, peaking around days 14-16, and improved flourishing from day 14. Vitamin C, on the other hand, marginally improved mood by day 12.

Lead author Dr Ben Fletcher, who carried out the research as part of his Ph.D. in Otago, says understanding the nuances of when and how these effects occur on a day-to-day basis adds to our knowledge of the potential mental health benefits of vitamin C-rich foods and supplements.

“It helps us see that what we eat can have a relatively quick impact on how we feel.

“Our participants had relatively good mental health to begin with, so they didn’t have much room for improvement, but they still reported benefits from the kiwifruit or vitamin C interventions,” he says.

He adds that although vitamin C tablets show some improvement, the study highlights the potential synergistic effects of eating whole foods like kiwis.

“We promote a holistic approach to nutrition and wellness, incorporating a variety of nutrient-dense foods into your diet.”

In addition to the direct implications for people seeking to improve their mental wellbeing, Professor Connor says the study introduces a new methodology to nutrition research.

“Using intensive smartphone studies offers real-time understanding of day-to-day changes in mood-related outcomes.”