Why Eating Kiwi May Improve Your Well-being

According to a new study, eating two kiwifruits per day can help improve your mood and overall sense of well-being. The study looked specifically at SunGold kiwis.

The September study was sponsored by Zespri, the producer of SunGold Kiwifruits, and results were published in the journal Nutrients. Researchers divided 167 adults into three groups. One group consumed two SunGold kiwifruit (providing approximately 260 mg vitamin C per day), the second group took a daily chewable vitamin C tablet (providing 250 mg vitamin C per day), and the third group took a chewable placebo tablet every day.

The intervention period lasted for four weeks and concluded with a "washout period" to allow the researchers to see whether any positive outcomes continued once the interventions were stopped. 

According to the study's findings, the people who ate two kiwis and the people who took the daily vitamin C supplement had a plasma vitamin C level that reached saturation levels within two weeks. Once plasma vitamin C concentrations reach saturation, additional vitamin C is mostly excreted in the urine and isn’t used by the body.

Beyond the positive plasma vitamin C results, outcomes appear to be slightly better for the kiwi group. Those who ate the kiwis showed significantly improved mood and well-being during the intervention period, and these outcomes continued during washout.

Although those in the group who took vitamin C supplements experienced positive outcomes as well—specifically decreased fatigue and increased well-being—these outcomes were only seen if an individual started the trial with a vitamin C deficiency. The people who took vitamin C supplements in the absence of deficiency did not experience any impact on vitality. Conversely, those in the SunGold kiwi group experienced positive outcomes regardless of their baseline vitamin C level. 

"This study highlights how getting nutrients from food sources can be beneficial— and in some cases, even more beneficial than getting nutrients from supplements," Brittany Scanniello, RD, LD, a Colorado-based registered dietitian, tells Verywell.

Why SunGold Kiwis?

SunGold Kiwis are a unique brand of kiwi variety that has golden flesh and is rich in vitamin C. They are so rich, in fact, that two of the kiwis will provide you with more vitamin C than an orange.

The study's authors suggest that the vitamin C content of the SunGold kiwi could be an important part of how it improves vitality; however, it might not be the only factor to consider.

In the study, the positive effects of eating SunGold kiwis were greater than simply taking a vitamin C supplement. There could be an important difference between single-nutrient supplementation with a vitamin C tablet compared to providing the same amount of vitamin C from whole fruit.

Diet's Role in Vitality

Vitality is a subjective outcome and is related to feelings of less fatigue, improved mood, and being active. Many factors may play a role in improving vitality, such as getting quality sleep. Practicing yoga has also been shown to help improve one's sense of well-being.

Diet is also thought to play a role. Previous research suggests that one's intake of fruits and vegetables—many of which are rich sources of vitamin C—is associated with improved feelings of vitality, less depression, and other positive outcomes.

When you eat a kiwi, you are not only getting vitamin C, but you are also getting a healthy dose of fiber, folate, potassium, and other nutritional factors. When combined, these nutrients might play a greater role in vitality than a single nutrient. 

Vitamin C

Vitamin C deficiency has been linked to depression and fatigue. Therefore, adequate vitamin C intake (which is more likely in people who eat a diet rich in produce) could be a factor that influences kiwi's effect on vitality.

“While often touted as an ‘immunity booster’, benefits from consuming Vitamin C-rich fruits and vegetables seem to go far beyond potential illness prevention,” Elise Compston, RD, LD, a Reno-based registered dietitian, tells Verywell.

“Another similar study suggests that subjects who consume more fruits and vegetables have an overall improvement in mood," Compston says. "In fact, high consumption of fruits and vegetables (around 7-8 servings per day) predicted improvements in subjects’ moods the following day.”

Not having enough vitamin C in your body could result in your body not producing enough of the “feel-good” dopamine neurotransmitter. Eating more vitamin C-rich foods could help prevent or at least reduce your risk of a deficiency.

Certain foods have shown to play a direct role in improved vitality, including seafood, pomegranate juice, and as the recent research shows, kiwis.

All of these foods have “shining star” nutrients like vitamin C or DHA fatty acids, but the question is whether it's an individual nutrient or the combination of nutrients that the food provides that has a positive effect on vitality. In the case of kiwis, the fruit contains vitamin C along with other beneficial nutrients, like fiber. 

“Emerging research suggests there may be ties between a healthier microbiome and mental health. Fiber-rich foods like kiwi can help support the beneficial bacteria in the gut,” Compston says. Therefore, kiwis might support vitality for many reasons, not just their vitamin C content.

What If You Don't Like Kiwi?

If you don't like kiwis (or are allergic to kiwis), know that they are not the only food that is a rich source of vitamin C, fiber, and other important nutrients. "If you don't care for kiwis but want other natural sources of vitamin C and other nutrients, you can enjoy foods like strawberries, oranges, grapefruit, and broccoli,” Carrie Gabriel, MS, RD, a Los Angeles-Based Registered Dietitian, tells Verywell. 

Gabriel also says not to only focus on your diet if you want to support or improve your vitality. "While eating certain fruits and vegetables are great choices, doing other things like getting quality sleep, drinking adequate water, and limiting alcohol can all do wonders for your mood, energy, and overall well-being," Gabriel says.

Compston agrees, adding that you should “skip the supplements and opt for foods first. Beyond the potential to boost your mood, whole foods rich in Vitamin C also include other vitamins and minerals, dietary fiber, and protective phytochemicals, not found in single-ingredient supplements."

Phytochemicals, which are found in kiwis and other foods, "have been associated with improved eye health, reducing free radicals and the risk for heart disease and cancer, and slowing premature aging," Compston says.

If you do like kiwis, there are plenty of reasons to make them a regular part of your diet, and if you're vitamin C deficient, they might help improve your levels (and your well-being). If you don't like them, there are plenty of other foods rich in vitamin C that can provide other nutritional benefits as well.

You might be able to have a kiwi or two a day to keep the doctor away, but if you have low levels of any nutrient, you should talk to your healthcare provider about the best way to treat it.