What's the first thing you see inside the doors of your grocery store? Most stores put colorful, fresh fruits and vegetables up front. But should you bypass them to get the most nutritional bang for your produce buck?

The answer, surprisingly, is sometimes yes. Some canned and frozen varieties of fruits and vegetables actually pack a bigger wallop of nutrients than their fresh counterparts.

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All forms of produce deliver fiber and phytochemicals -- compounds in plants that pack varied health benefits -- in low-calorie units.

In many cases, fresh vegetables are best, especially when it comes to fiber. Helen Rasmussen, senior research dietitian at the Jean Mayer USDA Human Nutrition Research Center on Aging, told "Ask Tufts Nutrition" that raw food sometimes can't be fully processed by the body because of their fiber cells. Cooking breaks down those walls and can make nutrients more readily available to the body.

Also, the time that most fresh produce in supermarkets spends in shipping and then on store shelves depletes their nutrients.

Why Processing Protects

"One reason canned (and frozen) fruits and vegetables sometimes rank nutritionally superior to fresh produce is they're usually processed immediately after harvest, when nutrient content is at its peak," according to Colorado State University's Extension Office.

"The technique of flash-freezing is used, where the vegetables are frozen very quickly and nutrient levels are not as likely to degrade. For example, frozen peas have 60 percent more carotene -- and similar levels of vitamin C -- to the fresh peas you buy in pods," according to Roughage.com, nutritionist Kathryn Elliott's blog.

In 1998, the Food and Drug Administration said frozen fruits and vegetables provide the same essential nutrients and health benefits as fresh. In fact, the agency suggests that mixing fresh, frozen and canned items in your grocery cart can ensure that you get the recommended five servings a day.

"If you shop once a week or less often, buy both fresh and processed -- that is, canned or frozen -- fruits and vegetables and juices. Use the fresh first; save the processed items for use later," the FDA said.

Cooking Can Boost Nutrients

Canning is a slightly different story than freezing because of the heat used to kill bacteria. In some cases, that process depletes nutrition; in others, it boosts the food's healthy profile. The FDA reports that the 1,500 types of canned food make up 12 percent of grocery sales in the U.S.

"Some of the canning processes may destroy some of the nutrients. Not a lot, but some," said Omaha registered dietitian Dawn Ballosingh, who works with families through the One World Community Health Center's Women's Infant and Children's program. "Water-soluble vitamins (including, A, D, E and K) -- you'll lose some of those."

Canning does such good things for tomatoes, though, that ConAgra Foods touts the benefits on its Web site for Hunt's.

"Fresh tomatoes are loaded with lycopene, but scientists have discovered that more lycopene is absorbed from cooked or processed tomatoes than from raw ones. Lycopene in tomatoes is converted by the temperature change involved in processing which allows the body to absorb it more easily," according to Hunts.com.

A study at Turkey's Ege University found that sun-dried tomatoes do an even better job of delivering lycopene. Studies showed 50 percent more of the phytochemical per serving compared to canned and three times as much as fresh, according to a summary of the study in Shape Magazine.

Colorado State Extension reported that most brands of canned apricots, spinach and pumpkin provided more vitamin A per serving than fresh, and canned asparagus, potatoes and spinach tended to outrank or equal fresh-cooked varieties for vitamin C.

Other Additives

Frozen and canned vegetables can contain additives that you won't find in the fresh produce aisle, though. Joan Sather, a registered dietitian at the University of Nebraska Extension Office for Douglas and Sarpy Counties, said careful shopping will help you bring home the products that are nutritionally equal to fresh.

"Read the label. Look for sodium. Even with frozen -- you have frozen vegetables, but you also have veggies in cream sauce or cheese sauce. There are going to be better choices," Sather said. "Make sure (your frozen fruit package) doesn't say 'sweetened.'"

Price Difference

Price may be a reason some families choose one variety over another.

For example, Midwestern grocer Hy-Vee offered 2 pounds of fresh carrots for 88 cents in an October flier, while online retailer NetGrocer.com had 14.5-ounce cans of Del Monte sliced carrots for $1.55 and 16-ounce bags of frozen carrots for $3.85.

Different people prefer different forms of their food. Most professional chefs demand fresh produce for its taste and crunch. Sather said she teaches families to try different varieties until they find what they like.

"Understand that vegetables taste differently depending on how they're prepared," she said.

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