Foods rich in vitamin C can improve mood; however, the timecourse of these benefits is unknown. In new research, scientists from the University of Auckland and the University of Otago utilized intensive smartphone surveys from a three-armed placebo-controlled trial to determine mood-related changes following supplementation with kiwifruit, vitamin C or a placebo.
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Fletcher et al. suggest that kiwifruit consumption, and to a lesser extent vitamin C supplementation, can lead to mood-related improvements in a relatively short period of time (from 4 to 16 days), even in a relatively healthy population with good mental health. Image credit: Photo Mix.
A healthy diet rich in fruits and vegetables has been linked to better mental well-being.
Critically, diets rich in nutrient-dense fruits and vegetables may causally benefit mental health by lowering depressed mood or improving well-being.
Although the biochemical pathways linking fruits and vegetables to psychological symptoms are likely to be varied and complex, one vitamin that may contribute to such changes is vitamin C.
Vitamin C is involved in synthesizing neurotransmitters, peptide hormones and acts as a catalyst for several enzymes, all of which are required to maintain and promote healthy brain functioning, including mood.
Kiwifruit is an excellent source of vitamin C, which has shown a dose-dependent reduction in depression and total mood disturbance in young men who consume low levels of fruit and vegetables.
Previously, University of Otago’s Professor Tamlin Conner and colleagues demonstrated that two kiwifruit a day can promote markers of subjective vitality after two weeks of supplementation.
Improvements were similar for participants supplemented with vitamin C, though the greatest improvements occurred in participants with low vitamin C levels at baseline.
However, limited research has assessed how quickly mood improvements occur after introducing vitamin C supplements or whole food sources.
“Our new findings provide a tangible and accessible way for people to support their mental well-being,” Professor Conner said.
“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.”
The researchers carried out an 8-week dietary intervention in 155 adults with low vitamin C.
The participants took daily either a 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 scientists found kiwifruit supplementation improved vitality and mood within four days, peaking around 14-16 days, and improved flourishing from day 14. Vitamin C, on the other hand, marginally improved mood until day 12.
“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,” said Dr. Ben Fletcher, a researcher at the University of Auckland.
“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.”
“While vitamin C tablets showed some improvements, the study underscores the potential synergistic effects of consuming whole foods like kiwifruit.”
“We encourage a holistic approach to nutrition and well-being, incorporating various nutrient-rich foods into your diet.”
The results were published in The British Journal of Nutrition.
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Benjamin D. Fletcher et al. Smartphone survey data reveal the timecourse of changes in mood outcomes following vitamin C or kiwifruit intervention in adults with low vitamin C. British Journal of Nutrition, published online December 11, 2023; doi: 10.1017/S0007114523002787
