Kiwifruit has proven itself as a powerful mood booster, with researchers now suggesting it can improve vitality in just four days, and that the effects last for longer than those of vitamin C.
Co-author Professor Tamlin Conner, from New Zealand’s University of Otago, said the findings of a recent smartphone survey provide a tangible, accessible way for people to support their mental well-being.
“Just small changes in your diet, like adding kiwifruit, could make a difference to how you feel every day,” she said.
Vitamin C intake has been associated with improved mood, vitality, well-being, and lower depression, while vitamin C deficiency is associated with higher depression and cognitive impairment, reports News Medical.
However, Conner said limited research has assessed how quickly mood improvements occur after introducing vitamin C supplements or whole food sources.
The team aimed to fill that gap with an eight-week dietary intervention of 155 adults with low vitamin C.
Participants took either a daily vitamin C supplement, placebo, or two kiwifruit. They then reported their vitality, mood, flourishing, sleep quality, sleep quantity, and physical activity using smartphone surveys.
The researchers found kiwifruit supplementation improved vitality and mood within four days, peaking at around 14-16 days, and improved flourishing from day 14.
Vitamin C, on the other hand, marginally improved mood until day 12.
Lead author Dr Ben Fletcher, who conducted the research as part of his PhD at Otago, said understanding the nuances of when and how these effects occur day-to-day contributes to our knowledge of the potential benefits of vitamin C-rich foods and supplements on mental health.
“This helps us see that what we eat can have a relatively fast impact on how we feel. 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.”
He added that while vitamin C tablets show some improvements, the study underscored the potential synergistic effects of consuming whole foods like kiwifruit.
In addition to the direct implications for people seeking to improve their mental well-being, Conner said the study, published in The British Journal of Nutrition, introduces a novel methodology in nutritional research.
“Intensive smartphone surveys offer a real-time understanding of the day-to-day changes in mood-related outcomes.”
Study details
Smartphone survey data reveal the timecourse of changes in mood outcomes following vitamin C or kiwifruit intervention in adults with low vitamin C
Benjamin Fletcher, Jillian Haszard, Margreet Vissers, Tamlin Conner.
Published in The British Journal of Nutrition on 11 December 2023
Abstract
Vitamin C-rich foods can improve mood; however, the timecourse of these benefits is unknown. This study utilised intensive longitudinal smartphone surveys from a three-armed placebo-controlled trial to determine mood-related changes following supplementation with vitamin C (250 mg tablet/d), kiwifruit (2 SunGold™ kiwifruit/d) or a placebo (1 tablet/d). Secondary data were analysed from the KiwiC for Vitality trial (Trial ID: ACTRN12617001031358). Adults (n 155, 63 % female, aged 18–35 years) with low plasma vitamin C (<40 μmol/l) completed a 14-d lead-in, 28-d intervention and 14-d washout. Participants self-reported vitality (SF-36), mood (POMS total mood disturbance), flourishing (flourishing scale), sleep quality, sleep quantity and physical activity every second day using smartphone surveys. Plasma vitamin C, measured fortnightly, reached saturation after 2 weeks of vitamin C or kiwifruit supplementation. Kiwifruit supplementation improved vitality and mood within 4 days, peaking around 14–16 days, and improved flourishing from day 14. Vitamin C marginally improved mood until day 12. Incremental AUC analyses revealed significant overall effects of kiwifruit consumption on vitality and mood compared with placebo, which were stronger than effects for vitamin C tablets, but attenuated when adjusting for covariates. Sensitivity analyses of participants with low baseline vitamin C status revealed improved mood (vitamin C and kiwifruit) and flourishing (kiwifruit only). This is the first study to use intensive smartphone surveys to model the day-to-day timecourse of mood-related states following vitamin C intervention and highlights the value of using smartphone surveys to reveal the temporal changes in mood-related outcomes following nutrient supplementation.
News Medical article – Kiwifruit improves vitality and mood in as little as four days (Open access)
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