Kiwifruit: Antioxidant Power in Quantity and Quality

Antioxidants include vitamins and phytochemicals called flavonoids that may have the power to neutralize unstable molecules called free radicals, which may be linked to chronic disease and aging.

08/07/08 Not all fruits are created equal when it comes to their antioxidant powers in the body: kiwifruit is among the highest in bioavailability compared to other antioxidant-rich fruits and berries in a recent small-scale study published in the Journal of the American College of Nutrition.

Antioxidants include vitamins and phytochemicals called flavonoids that may have the power to neutralize unstable molecules called free radicals, which may be linked to chronic disease and aging. Consumption and increased absorption of antioxidants may help prevent certain types of cancer, heart disease and signs of aging. Antioxidant-dense foods, like kiwifruit, are increasingly gaining popularity with consumers who look for health via natural and functional foods in addition to medicine.

Researchers at the U.S. Department of Agriculture's (USDA's) Arkansas Children's Nutrition Center in Little Rock performed a comparison study between kiwifruit, red grapes and strawberries which showed the antioxidants in kiwifruit to be the most easily metabolized and absorbed into the bloodstream. Dr. Ronald Prior and his team measured the antioxidants in the body by noting increases in blood antioxidant capacity and cells' increased resistance to oxidative damage induced by hydrogen peroxide.

To test kiwifruit's antioxidant capacity, seven healthy women were given two servings of green Hayward kiwifruit (300g) per day. Blood samples were taken from the participants after an overnight fast before fruit ingestion and at 1.5, 3.0 and 4.5 hours after fruit ingestion. The results found that kiwifruit provided for an antioxidant intake score of 12.5, as compared to grapes (4.2) and strawberries (1.7). Kiwifruit resulted in the most significant increase in antioxidant metabolism and absorption.

While scientists may not yet know the exact mechanism that causes certain high-antioxidant fruits to perform better in the body than others, they do know that antioxidants are paramount to good nutrition. As Dr. Prior asserts in USDA press materials, "We're learning that antioxidants should be consumed with every meal, and if you routinely skip antioxidants in your diet, over time, the excess number of free radicals being produced may begin damaging cellular components, ultimately leading to atherosclerosis, cancer, and other diseases."

Prior notes that volunteers' increased blood antioxidant capacity may, in part, be attributed to the high vitamin C content of kiwifruit. While one cannot necessarily translate increased antioxidants in the bloodstream into a potential decreased risk of chronic degenerative disease without further long- term clinical studies, kiwifruit appears to be a strong antioxidant performer.

Beyond antioxidants, kiwifruit play an important role in daily nutrition. A two piece serving of either ZESPRI GREEN or ZESPRI GOLD kiwifruit provides twice the vitamin C of an orange, as much otassium as a banana and as much fiber as many whole grain cereals (4 grams and 2 grams per serving respectively). ZESPRI GREEN is fuzzy on the outside and tastes tangy and fresh, while ZESPRI GOLD has smooth skin and a tropical-sweet flavor.

ZESPRI International is the world's largest kiwifruit marketer, with over 2,500 growers producing and exporting more than 100 million trays of kiwifruit a year to over 60 countries.