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Health Benefits of Kiwi Fruit

If you are not eating kiwi fruit, you should definitely add this good-for-you fruit to your diet if you don't want to miss out on some amazing health benefits. In recent years, scientists have studied the effects of kiwi fruit, or compounds found in kiwi fruit, on everything from digestion and lung function to DNA repair and eye health. Below, we take a look at 5 potential health benefits of kiwi fruit, plus provide 5 tips to help you reap those benefits.

Why Kiwis Are Good for You: 5 Reasons

Kiwi Fruit

1. They have beneficial effects on the digestive system

Both anecdotal evidence and scientific research support the claim that kiwi fruit helps fight constipation. A study published in the Asia Pacific Journal of Clinical Nutrition found that regular consumption of kiwi fruit resulted in bulkier and softer stools, as well as more frequent bowel movements in healthy elderly people [1].

Another study, published in the same journal, investigated the effects of kiwi fruit in people with IBS, and found that eating two regular green kiwi fruits daily improved bowel function in adults with constipation-predominant IBS [2]. IBS, which is short for irritable bowel syndrome, is a common disorder of the digestive system and is characterized by abdominal pain and either diarrhea, constipation or alternating diarrhea and constipation.

The mechanisms behind the beneficial effects of kiwi fruit on the digestive system are not fully understood, but scientists believe several kiwi fruit constituents are likely to play a role. These include dietary fiber, polyphenols and an enzyme called actinidin which breaks down proteins into amino acids. [1, 3]

2. They may help improve lung function

Not only do some asthma sufferers swear by vitamin C as a treatment for asthma symptoms like cough, also scientists have shown interest in the potential lung-health improving properties of foods that are rich in vitamin C, such as kiwi fruit, and vitamin C supplements. A case in point: In the late 1990s, a group of Italian scientists wanted to find out whether a high intake of citrus fruit and kiwi fruit is linked to a reduced risk of wheezing and other respiratory symptoms in children. Questionnaires were completed by parents of nearly 20,000 Italian children, and the winter intake of citrus fruit and kiwi fruit by each child was categorized as less than once per week, 1-2 per week, 3-4 per week, or 5-7 per week.

After controlling for a number of potential confounding factors, the researchers found that a high intake of citrus and kiwi fruit was associated with a reduced risk of respiratory symptoms such as wheezing, shortness of breath, nocturnal cough and chronic cough. [4]

In another study, researchers analyzed the results of nine previous studies exploring the potential health benefits of vitamin C in people with exercise-induced bronchoconstriction, or EIB, which occurs when the airways of the lungs become narrow as a result of vigorous exercise. The researchers found that all nine randomized trials suggest that vitamin C can have positive effects on pulmonary functions and respiratory symptoms in people engaging in heavy exercise. [5]

3. They provide protection against DNA damage

DNA damage has emerged as a major culprit of cancer, and foods and supplements that aim to prevent or repair this damage are thought to be good against this serious disease. As kiwi fruit is rich in vitamin C, a known antioxidant, it is not surprising that scientists have been keen to explore the potential anti-cancer effects of kiwi fruit.

In one such study, conducted in New Zealand, 12 healthy volunteers were put on a special diet and lifestyle regime. In addition, six randomly selected volunteers were asked to consume a daily dose of kiwi fruit, and the other six were asked not to eat kiwifruit.

The result? A significant increase in the ability of leukocytes to repair DNA breakage caused by free radicals was observed in the kiwi fruit group, compared with the control group. The researchers concluded that a "prescription" of daily kiwi fruit might be a sustainable way to reduce some of the risk factors associated with cancer in the general population. [6]

Another study, published in the journal Nutrition and Cancer, found that consumption of kiwi fruit led to an increased resistance of DNA to oxidative damage caused by free radicals in isolated lymphocytes, in comparison with lymphocytes collected after a control drink of water. In a separate experiment, the same researchers found that a simple extract of kiwifruit was more effective at protecting DNA from damage than a vitamin C solution (of equivalent concentration). As a result, the team concluded that the antioxidant activity of kiwi fruit is not entirely attributable to the vitamin C content of the fruit. [7]

4. They offer benefits for the skin

Aside from its health benefits, kiwi fruit may offer beauty benefits by helping keep your skin smooth and elastic. As explained above, kiwi fruit contains vitamin C and other compounds that act as antioxidants. These antioxidants help neutralize free radicals that not only promote the development of age-related diseases, such as cancer, but that promote wrinkling of the skin. On top of that, vitamin C plays an important role in collagen synthesis [8]. For those who missed the memo, collagen is a structural protein that gives the skin its strength and thickness.

The benefits of vitamin C for the skin have also been "proven" in a couple of observational studies which found that higher intakes of vitamin C from the diet were associated with better skin appearance, with significant decreases in skin wrinkling [8].

5. They are rich in nutrients that are good for your eyes

Affecting millions of people, cataracts and age-related macular degeneration are common causes of visual impairment and acquired blindness in aging Americans. Kiwi fruit is rich in lutein/zeaxanthin [9], a carotenoid combo that is good for your eyes. These oxygen-containing carotenoids are highly concentrated in the human retina, the light-sensitive tissue lining the back of the eye. [10].

Many studies suggest these macular carotenoids can help reduce the risk of chronic eye diseases, including age-related macular degeneration and cataracts, and they appear to work their protective magic in a number of ways. First, they act as antioxidants, protecting the eyes directly by reducing oxidative stress. Second, they absorb blue wavelengths of light, protecting the retina from light-related damage. And third, evidence also indicates that lutein protect against inflammation, a pathogenic mechanism in many diseases affecting the eyes. [10]

How to Reap the Benefits: 5 Tips

Can't wait to start reaping the health benefits of kiwis? The great thing is that you can buy fresh kiwis year-round almost everywhere in the world, so most people shouldn't have trouble incorporating this healthy fruit into their diet. Here are some additional tips to help you maximize the nutritional and health benefits of your kiwi-enriched diet:

  • Go for organic kiwis if you can afford to do so. A UC Davis study found that organic kiwis had more vitamin C and phenolic compounds and stronger antioxidant activity than conventional kiwis grown on the same farm in California [11], suggesting that organic kiwi fruits are healthier than regular kiwis.
  • Don't only stick to the regular green kiwis: also the yellow-fleshed golden kiwis are good for you. In fact, in the battle green vs golden kiwi fruit, the golden variety wins the gold metal in terms of vitamin C content!
  • Try kiwiberries (Actinidia arguta) when they are in season and available in well-stocked grocery stores. These miniature kiwis have been shown to have even more in vitro antioxidant activity than regular green kiwis [12].
  • If you have an Excalibur dehydrator or another good food dehydrator, consider making kiwi chips at home by dehydrating sliced kiwi fruit. Dehydrating does not destroy the beneficial fiber in kiwi fruit, nor does it have a huge impact on the vitamin C content of the fruit [13].
  • Consider freezing kiwi fruit for later use. Frozen kiwi fruit does have the same texture as its fresh counterpart, but it works perfectly in fruit smoothies, desserts that use pureed frozen kiwi fruit, and other recipes that do not require whole, firm pieces.

Book You May Like
Book on the Healthiest Foods In this indispensable guide book to the healthiest foods on earth, bestselling author and acclaimed nutrition specialist Jonny Bowden, Ph.D., C.N.S., presents 150 super-healthy foods in a concise, reader-friendly format. You'll learn what nutrients each of the featured foods contains, what form contains the most nutrients, whether the food has been shown to fight any diseases, where you can find it, and much more. You'll also find tons of mouthwatering recipes using some of the world's most nutrient-dense foods. Available from Amazon.