Foods containing vitamin C are known to have a positive impact on mood, but the timeline for these effects is not well understood. Researchers from the University of Auckland and the University of Otago used intensive smartphone surveys in a placebo-controlled trial to track changes in mood after supplementation with kiwifruit, vitamin C, or a placebo.
They found that consuming kiwifruit and, to a lesser extent, vitamin C can lead to mood improvements within a relatively short period of time (from 4 to 16 days), even in a population with good mental health.
A diet rich in fruits and vegetables has been associated with better mental well-being. These foods may have a causal benefit on mental health by reducing depressed mood or enhancing well-being.
One specific vitamin that could contribute to these changes is vitamin C. It plays a role in synthesizing neurotransmitters, peptide hormones, and acts as a catalyst for several enzymes necessary for maintaining healthy brain function and mood.
Kiwifruit is an excellent source of vitamin C and has been shown to reduce depression and total mood disturbance in young men with low fruit and vegetable consumption.
Previous research demonstrated that consuming two kiwifruit a day can improve subjective vitality after two weeks of supplementation, with similar improvements seen in participants taking vitamin C supplements, especially those with low vitamin C levels at the beginning.
However, there has been limited research on how quickly mood improvements occur after taking vitamin C supplements or whole food sources.
The new findings offer a practical way for people to support their mental well-being by making small changes in their diet, such as adding kiwifruit.
The researchers conducted an 8-week dietary intervention with 155 adults with low vitamin C levels. Participants took either a vitamin C supplement, placebo, or two kiwifruit daily and reported their vitality, mood, flourishing, sleep quality, sleep quantity, and physical activity using smartphone surveys.
The study found that kiwifruit supplementation improved vitality and mood within four days, peaking around 14-16 days, and improved flourishing from day 14. Vitamin C marginally improved mood until day 12.
Understanding the specific timing and manner of these effects on a day-to-day basis contributes to our knowledge of the potential benefits of vitamin C-rich foods and supplements for mental health.
The researchers emphasize the potential synergistic effects of consuming whole foods like kiwifruit and advocate for a holistic approach to nutrition and well-being, incorporating various nutrient-rich foods into one’s diet.
The study was published in The British Journal of Nutrition.
(source: 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)
