- Diet influences aspects of physical and mental health and contributes to overall well-being.
- Researchers are still trying to understand which components of the diet may have the most impact on mental health.
- A recent study found that eating kiwifruit helps improve mood within a few days in people with low vitamin C levels.
Eating a healthy diet helps support quality of life, but researchers and nutritionists are still trying to understand the mechanisms that govern the link between food and mood.
A recent study published in British food magazine investigated how kiwi and vitamin C affected mood and how quickly participants experienced mood improvements.
The results show that eating kiwifruit improved mood after 4 days, and the impact on vitality and mood was slightly stronger compared to study participants who received vitamin C supplements.
The findings point to the effects of vitamin C on mental health and that whole food sources may be the best way to get this nutrient.
Fruit is part of a healthy diet, and kiwis are one option that offers several
For example, kiwifruit can help with gastrointestinal function and improve blood sugar and lipid levels. It contains fiber, potassium and vitamin E, and a fairly high level of vitamin C.
Previous studies suggest that vitamin C supplements and vitamin C-rich fruits can help improve mood.
For the current study, researchers hypothesized that vitamin C might play a role in mood and healthy brain function. They were curious about how fruit intake might affect mental health over time.
This particular study analyzed data from a three-arm, placebo-controlled trial. The participants were adults between 18 and 35 years of age with low plasma levels of vitamin C.
Researchers divided the participants into three groups: one group received a daily vitamin C supplement, the second received two kiwis daily and the third received a placebo tablet daily.
Researchers used smartphone surveys to collect data from participants, and participants had blood tests done every two weeks.
They could not blind participants or researchers to the Kiwi intervention. However, researchers and participants did not know who received the placebo versus vitamin C tablets until after the study was completed.
Participants took their assigned intervention or placebo for four weeks and answered surveys every other day. The surveys collected data on various components, including:
- energy and fatigue
- sleep quality and quantity
- physical activity levels
Based on their analysis, researchers found that participants who consumed the kiwi saw an improvement in mood and vitality around day four and an improvement in flowering around day fourteen.
Mood improvements in these participants peaked between day 14 and day 16. Participants in the vitamin C supplement group saw mood improvements until about day 12.
Study author Tamlin Conner, PhD, a psychological scientist and professor at the Department of Psychology at the University of Otago, New Zealand, explained Medical news today:
“As part of this placebo-controlled nutrition trial, we used smartphone technology to examine mood over an eight-week period and found improvements in mood after introducing a whole-food vitamin C product (Sungold kiwifruit) in just four days. and then a peak of about two weeks.
Our research program suggests that it is valuable to regularly measure mood changes in real time in daily life within intervention studies to understand patterns and time frames of change. We were surprised that participants randomized to the whole food condition (2 Sungold kiwifruit per day) showed improvements in their mood as early as four days after the intervention.”
The study highlights the importance of including vitamin C in a diet and how this nutrient can benefit mental health. It also suggests that the benefit may be most pronounced when obtained from whole food sources.
“This trial highlights a critical point of difference between diet-based vitamins and vitamins from synthetic sources,” said non-study author and registered dietitian nutritionist Rick Miller.
“They are not equivalent, and a whole food-first approach should always be the first choice to meet nutritional needs and symptoms that may be related, such as mood.”
Despite the promising findings supporting the benefits of kiwifruit consumption, the research has some limitations.
First, it was observational, so it can’t prove that kiwis cause mood improvements or other effects. Second, it was based on self-reporting by participants, which does not always guarantee accuracy.
The study was also conducted over eight weeks and included only a relatively small number of adult participants in a specific age range.
The design of the surveys may also have limited the findings. For example, researchers included only limited Mood States Rating Scale Profile data in participant surveys, and researchers sent participant surveys only every other day.
The participants were also relatively psychologically healthy, so it’s unclear how helpful the intervention would be for people who are more emotionally distressed.
Researchers also did not specify what time participants should consume supplements or kiwifruit, and future research could investigate the impact of this timing on results.
Ethnic differences between the groups may also have influenced the results. Researchers also acknowledge that components of kiwifruit other than vitamin C likely contributed to the participants’ perceived mental health benefits. Finally, researchers admit that there was some risk of positive response bias and that there was a non-randomized element in assigning certain clinics to the kiwi or tablet intervention.
Dr. Conner noted the following areas for further research:
“We would like other scientists to test for time-course patterns in mood after nutritional interventions. Replication is important in science. For whom are nutritional interventions most useful? Do some people benefit more or less from vitamin C? Are there demographic, psychological, or environmental differences that predict variability in the mood benefits of vitamin C?”
Overall, the results still point to the benefits of kiwi and vitamin C for mental health.
“The strength of the findings for people with low vitamin C levels is impressive, and it was impressive to see how kiwi separated from vitamin C tablets, also showing no response to placebo vitamin C tablets ,” Dr. Alex Dimitriu, double board-certified psychiatrist and sleep medicine specialist and founder of Menlo Park Psychiatry & Sleep Medicine in California, told MNT. Dr. Dimitriu was not involved in the investigation.
“It might have been a good idea to add fruit control in addition to kiwis that doesn’t contain much vitamin C. For anyone who doesn’t eat enough citrus fruits or is believed to have low vitamin C levels, studies like this support a substantial benefit from a relatively risky and cost-free intervention to get more vitamin C in their diet,” he added.
“Given the clear benefits of normal vitamin C levels, this study underlines the importance of a healthy intake of citrus fruits.[or] vitamin C in one’s diet. In our impatient world, the speed of these improvements is remarkable.”