Eating Kiwi Could Make A Difference To How You Feel

“It’s great for people to know that small changes in their diet, like adding kiwifruit, could make a difference in how they feel every day,” said Co-author Professor Tamlin Conner, of the Department of Psychology.

Vitamin C is associated with improved mood, vitality, well-being, and lower depression, and a deficiency is associated with cognitive impairment and higher depression. However, there is little research on how quickly improvements occur after consuming vitamin C supplements or whole food sources. This study set out to find some of these answers. 

Over an 8-week dietary intervention, 155 adults with low vitamin C levels received either a daily vitamin C supplement, two kiwifruits, or a placebo, and they reported their mood, vitality, flourishing, sleep quality, sleep quantity, and physical activity using an app on their smartphones. 

According to the researchers, eating kiwifruit improved vitality and mood within four days, reaching a peak between 14-16 days, and improved flourishing from day 14, while vitamin C supplements improved mood until day 12.

“This helps us see that what we eat can have a relatively fast impact on how we feel,” said Lead author Dr Ben Fletcher, who conducted the research as part of his Ph.D. at Otago. "Our participants had relatively good mental health to begin with so had little room for improvement, but still reported the benefits of kiwifruit or vitamin C interventions.”

The vitamin C supplements did show some improvements; however, the study demonstrates the potential synergistic effects of consuming fresh whole foods such as kiwifruit over dietary supplements to improve mental well-being.

“We encourage a holistic approach to nutrition and well-being, incorporating various nutrient-rich foods into your diet,” said Fletcher. “The use of intensive smartphone surveys offers a real-time understanding of the day-to-day changes in mood-related outcomes.”