U.S.-Thai Scientific Efforts Peg Guava's Nutritional Value

A cooperative study by Agricultural Research Service (ARS) and Thai scientists has shown that guava fruit is high in antioxidants—adding it to the list of other antioxidant-rich foods such as blueberries, black beans and broccoli.

Because tropical fruits aren't usually grown in cooler U.S. climates, little information about their nutritional value—especially of that of the more "exotic" species—has been developed. But South Florida growers are beginning to produce guava, carambola, pitaya, mamey sapote, sapodilla, lychee, longan, mango and papaya to meet rising consumer demand for unusual fruits.

At the ARS U.S. Citrus and Subtropical Products Research Laboratory in Winter Haven, Fla., scientists have been using standard methods to analyze tropical fruits from South Florida for components that could be beneficial to human health.

Leading the research is ARS horticulturist Elizabeth Baldwin, with ARS chemists John Manthey and Kevin Goodner, along with cooperating scientists at the University of Florida's Citrus Research and Education Center in Lake Alfred, and at Siam University-Bangkok and Chiang Mai University, both in Thailand. The Thai researchers are testing Southeast Asian variations that are not native to Florida. The Tropical Fruit Growers of South Florida provided a grant to make the research possible.

Fruits and vegetables play a significant role in the human diet because they provide an optimal mix of antioxidants such as vitamins C and E, polyphenols, carotenoids and complex carbohydrates. Antioxidants are plant chemicals that have the power to neutralize free radicals, toxic compounds generated inside the human body and also found in pollutants like cigarette smoke. Getting rid of these damaging compounds can help improve human health, since free radicals cause oxidative damage to human cells that can trigger various chronic diseases.

In the study, guava's antioxidant content ranked just below that of blueberries, which is No. 1 in antioxidant activity. Other fruits ranking surprisingly high were carambola, lychee, mango and papaya.

Read more about these studies in the October 2007 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.