Preserving Vitamin Content in Foods

April 11 -- Many of us know that fresh fruits, vegetables and juices are among the best sources of vitamins. But when it comes to taking advantage of these health-boosting properties, experts say it's a race against the clock.

An example is orange juice. A new study published in the April issue of the Journal of the American Dietetic Association reports that if not consumed quickly enough, O.J. can lose its vitamin C content by as much as 100 percent.

Frozen O.J. lost up to 50 percent of its vitamin C within four weeks of opening the package, scientists found, and some ready-to-drink preparations lost all of it within that time frame.

Experts say this is not an issue of "bad" orange juice — it's just that some nutrients found in food are naturally pretty finicky and can break down over time. That's especially true with vitamin C. Thus the researchers recommend purchasing O.J. at least three to four weeks before the expiration date and consuming what you buy within one week.

"One of the things that people need to remember is that vitamins and minerals are sensitive ... so we need to handle them with some care," says Connie Diekman, director of university nutrition at Washington University in St. Louis.

Vanquishing Vitamin Loss

It's sound advice for much more than just orange juice, experts say. Everything from fresh lettuce to peaches can be robbed of some nutrients over time — particularly those sensitive vitamins. But there are ways to preserve them and maybe slow some of that loss.

The three main culprits that strip vitamins from foods — especially produce — are heat, light and air. Too much exposure to any one or all three of these can accelerate vitamin loss over time.

"Even before you open your mouth to enjoy [fresh produce], you can start losing those nutrients," says Jackie Newgent, a chef and registered dietitian and culinary instructor at the Institute of Culinary Education in New York City.

But there are small steps that can be taken to help maximize the vitamins found in produce when shopping for, preparing and storing it.