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A glass of cloudy apple juice, sometimes called cider, may contain more healthful antioxidants than clear apple juice, which is nevertheless more popular.iStockphoto.com

Clear apple juice may be prettier, but cloudy apple juice is probably better for your health. A new study shows that cloudy juice can contain more than five times as much of a health-linked antioxidant as clear juice has.

The color of most apples, other fruits, and vegetables comes from a family of antioxidants called polyphenols. Studies have associated these chemicals with health benefits ranging from a reduced risk of cancer to improved brain functions.

Generally, the stronger the color of the fruit is, the higher the concentration of polyphenols will be. The skin and seeds of an apple are particularly high in these compounds, and the process of making clear apple juice removes this solid matter.

"It is better if you eat whole apples than juices. But for juices, it's better if you drink this cloudy juice," says the new study's lead author Jan Oszmianski, who studies fruit and vegetable processing at the Agricultural University of Wroclaw in Poland.

While scientists had widely assumed that cloudy juice (cider) ought to be more healthful, Oszmianski's study provides a more accurate picture of the difference in antioxidant activity between these two juice types. That's because the most common way to measure this activity requires a transparent sample. In other words, it only works well with clear juice.

Oszmianski and his colleagues employed a technique called electron paramagnetic resonance (EPR), which can measure the activity of antioxidants in both cloudy and clear juice. The method even accounts for polyphenols bound to solid bits of pulp, which include an especially potent class of polyphenols called procyanidins.

"This is the first time that I've seen [anyone] use [EPR] to measure antioxidant activity in plant extracts," says Joshua Lambert, assistant professor of chemical biology at Rutgers University in Piscataway, N.J., who was not involved in the study.

Oszmianski's team found that procyanidins were between 2.6 and 5.3 times as abundant in cloudy juice as in clear, depending on the variety of apple used. However, amounts of other antioxidants were more nearly equal between the two kinds of juice. Overall, the cloudy juice was 1.5 to 1.8 times as effective an antioxidant as the clear juice. Oszmianski and his colleagues report their results in an upcoming Journal of the Science of Food and Agriculture.

The reported numbers might even underestimate the difference, Oszmianski says, because his group used samples made in the lab rather than commercial apple juice. To make the clear juice, the researchers simply put the cloudy juice in a centrifuge. But commercial clarification processes involve aeration and treatment with enzymes and agents such as gelatin, all of which reduce polyphenol content. That leaves commercial clear juices with only one-tenth the antioxidant power of cloudy juice, says Oszmianski.

Representatives from the U.S. Apple Association in Vienna, Va. sought to downplay the differences between the two kinds of juice. "One thing that's unfortunate about this study is that it's taking two healthy products and trying to put one above the other," says Shannon Schaffer, communications manager for the association. "Clear apple juice, any kind of apple juice, has been shown scientifically to be very healthy."

Wendy Davis, director of communications and consumer health for the association, emphasizes that one study isn't enough to yield firm conclusions and that the researchers used only the Idared and Champion apple varieties in their study, while more than 2,500 varieties are used to make apple juice in the U.S.

The vast majority of juice sold in the U.S. is clear, Schaffer says.

"In Poland we have only clear juices," Oszmianski says. "It is a very big problem for me, and I'm trying to change this."

In recent years, scientists have shown that apples can reduce the occurrence of breast and colon cancer in rats, and that people who frequently eat apples tend to have a lower risk of lung cancer. While further research will be necessary to pin down the specific compounds in apples that create these salutary effects, scientists generally ascribe them to polyphenols or other antioxidants in apples.

Antioxidants work by mopping up highly reactive molecules called free radicals. These molecules can damage the body's cells by altering important enzymes or DNA. This damage can lead to cancer and other diseases associated with aging. The thinking goes that by neutralizing free radicals, antioxidants reduce the risk of these diseases.

Other foods also contain polyphenols, including berries, cantaloupe, grapes, pears, plums, broccoli, and cabbage. The compounds are also found in red wine, olive oil, green tea, and chocolate.

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