For the Most Vitamin C, Drink Packaged Orange Juice Soon After Purchase, Says Study by ASU's Polytechnic campus Professor

Even if the expiration date hasn't yet arrived, it's a good idea to drink orange juice as soon as possible after purchase, according to an Arizona State University's Polytechnic campus study of vitamin C content in orange juice, published in the April issue of the Journal of the American Dietetic Association.

The vitamin C content of increasingly popular ready-to-drink brands of orange juice can drop from 45 milligrams per cup to zero within four weeks after opening, according to a study led by Carol Johnston, a registered dietitian and professor of nutrition at ASU's Polytechnic campus. Her co-author was Dusti Bowling, an ASU graduate who is a former undergraduate student of Johnston.

The study also found frozen reconstituted orange juice contains more vitamin C than ready-to-drink juice, although the exact amounts depend on when the juice is consumed following purchase.

The study's authors do not offer a recommendation whether consumers should choose frozen or ready-to-drink juice, but do recommend that ready-to-drink orange juice should be purchased three to four weeks prior to the expiration date and consumed within one week of opening.

"We don't want people to stop drinking orange juice for any reason at all," Johnston said. "We just want them to know that the frozen concentrate orange juice contains more vitamin C and may be a better nutritional choice. People don't eat broccoli, spinach or red peppers daily, and the thing that's great about orange juice is Americans consume it regularly."

The researchers analyzed two brands of frozen juice and two brands of ready-to-

drink juice and found orange juice from concentrate contains 86 milligrams of vitamin C per fluid cup when first prepared, dropping to 39 to 46 milligrams after four weeks of storage.

Ready-to-drink juices, on the other hand, start with "significantly lower" amounts of vitamin C than frozen, according to the study - 27 to 65 milligrams per cup when the container is opened, and zero to 25 milligrams four weeks later.

Oxygen in the air is responsible for most vitamin C loss in packaged orange juice, meaning routine handling during the production process as well as storage in non-airtight containers after opening can reduce the amounts of vitamin C both before and after purchase.

While the average person needs only about six milligrams per day of vitamin C to avoid health problems like scurvy, Johnston said, "low intake of vitamin C can lead to fatigue, feelings of listlessness and may lead to more serious complications."

Johnston said previous studies have shown vitamin C deficiencies among U.S. adults have risen from five percent to 16 percent in the past 20 years, and the amount of vitamin C consumed by Americans has dropped 20 percent since the mid-1970s.

During roughly the same period, Johnston noted, "increasing sales of pasteurized, ready-to-drink orange juice resulted in a marked shift in the industry" - the number of factories producing concentrates decreased and the number producing ready-to-drink juice increased.

According to the study, the vitamin C content of orange juice is "highly variable and dependent on, for example, the variety and maturity of the oranges, fresh fruit handling, processing factors and packaging. Pasteurized, ready-to-serve orange juice typically contains 25 percent less vitamin C per serving than frozen concentrates, a result in part of heat destroying the vitamin C."

Bowling and Johnston's research was funded by the Howard Hughes Medical Institute through its Undergraduate Biological Sciences Education Program and the Lloyd S. Hubbard Nutrition Research Fund of the Arizona State University Foundation.