The common cold and the flu - both of which are caused by viruses - affect millions of people and cost billions of dollars every year.1,2 While there are antiviral drugs to treat the flu, treatments for the common cold mainly focus on relieving symptoms.
For most people, kiwi is not much more than a nice addition to a fruit salad. But as it turns out, kiwi is a powerhouse of nutrients and beneficial compounds. To explore its medicinal potential, researchers from New Zealand studied the effects of gold kiwifruit on cold and flu symptoms.
The trial had three components: an ex vivo study, a crossover clinical trial with older adults, and a crossover clinical trial with preschool children.
- The ex vivo study consisted of treating blood samples from volunteers between the ages of 23 and 48 with two different preparations of gold kiwifruit (a juice and a puree).
Researchers measured the effects of gold kiwifruit on human immune responses, particularly the innate and adaptive responses.
- The first clinical trial recruited 32 adults over the age of 65. They were split into two groups. For four weeks, the intervention group ate two fresh gold kiwis and two freeze-dried kiwis daily (the intervention group), while the placebo group ate two freeze-dried bananas every day.
Researchers studied the effects of both treatments on the duration and severity of cold and flu symptoms.
- The second clinical trial involved 66 children between the ages of two and five. For four weeks, half of them ate two servings of gold kiwifruit per day (the intervention group), while the other half ate two servings of banana daily (the placebo group).
Researchers assessed the frequency of cold and flu-like illnesses as well as reported symptoms.
In participants consuming gold kiwis, there were a significant increase in natural killer cell activity, which play a crucial role in the innate immune response.
The adult participants eating kiwi experienced a sore throat and head congestion for fewer days than those taking the placebo (2 days vs. 5.4 days for sore throat and 1 day vs. 4.7 days for head congestion). The severity of head congestion was also greatly decreased in the intervention group.
In the children's group, those eating kiwi had a substantially reduced incidence of cold and flu-like illnesses. In fact, they were almost 50% less likely to catch a cold or a flu than those eating bananas. Also, children in the kiwi group had lesser symptoms, including less crying, sore throats, headaches, and others.
What Does this Mean?
As shown in the results of this trial, eating kiwi can enhance the immune response by regulating the activity of immune cells and cytokines.
By boosting the immune responses, gold kiwi may help reduce the duration and severity of cold and flu symptoms as well as the overall likelihood of catching such illnesses. This is especially important for vulnerable populations, like children and the elderly.
These findings may not only encourage people to include kiwis in their daily diet, but they may also lead to the development of kiwi-based functional foods for boosting immunity.
- Journal of Food and Drug Analysis, Wellness foods based on the health benefits of fruit: Gold kiwifruit for immune support and reducing symptoms of colds and influenza, 2012
- CDC. (n.d.). Burden of Flu. Retrieved May 12, 2023, from https://www.cdc.gov/flu/about/burden/index.html
- University of Michigan. (2003). The common cold coughs up $40 billion annual price tag. Retrieved May 12, 2023, from https://www.cdc.gov/flu/about/burden/index.html