Amid the steady drumbeat from nutrition experts and others to consume a healthier diet -- particularly one rich in fruits and vegetables -- there often is a bias to eat more of the fresh variety for optimal nutrition. But is fresh always best? Not necessarily.

Dr. Cathy Kapica, PhD, RD, adjunct professor of nutrition at Tufts University, and Wendy Weiss, MA, RD, both with Ketchum Global Health and Wellness, conducted a market-basket study comparing the cost of obtaining key nutrients from canned, fresh, frozen and dried varieties of common foods. The study found that when price, waste and preparation time are considered, canned foods almost always offered a more affordable, convenient way to get needed-nutrients. The results of this research, funded by the Canned Food Alliance, will be presented at a poster session at Experimental Biology 2012 on April 22.

"With economic concerns at the forefront today, households are challenged to meet dietary recommendations within budgetary constraints," notes Kapica. "This research should assure families they are getting needed nutrition regardless of whether they choose canned, fresh, frozen or dried varieties. They can be confident in buying those foods that best meet their budgets, schedules, cooking abilities and taste preferences and still obtain important nutrients."

Key study findings included:

• Pinto Beans -- When the cost of preparation time is taken into consideration, canned pinto beans cost $1 less per serving as a source of protein and fiber than dried beans. This is because it takes about six minutes to prepare a can of pinto beans while it takes almost 2½ hours (soaking and cooking) for dried beans to be meal-ready.

• Tomatoes -- It is nearly 60 percent more expensive to obtain dietary fiber from fresh tomatoes as from the same portion of canned tomatoes. Not only is the price of canned tomatoes lower than fresh for the same serving size, but fresh tomatoes take longer to prepare, adding to the real cost of fresh.

• Corn -- When looking at purchase price alone, fresh corn is less expensive than canned or frozen. However, when the cost of waste (most notably the cob) is factored in, as well as time to prepare, canned corn offers the same amount of dietary fiber as fresh at a 25 percent savings.

• Spinach -- With a lower cost-per-serving than fresh or frozen, canned spinach provides vitamin C at an 85 percent savings when compared to fresh or frozen.

The market-basket study involved buying, preparing and analyzing canned, fresh, frozen and dried (where available)* corn, green snap beans, mushrooms, peas, pumpkin, spinach, tomatoes, pears, peaches, pinto beans and tuna fish. The foods were cooked so that an accurate comparison could be made. All varieties purchased were with no added salt or sugar when available.

Time is money as the adage goes, so to arrive at the actual cost of each type of food, time spent cleaning, preparing and cooking was recorded and calculated at a rate of $7.25 per hour (the minimum wage in New Jersey where the research took place). Many fresh foods that are sold by the pound, ounce or other measure require peeling, pitting, removing stems and other steps, which reduce the amount of food available for eating. Therefore, the cost of this waste was factored into the actual cost of a serving of those foods.

The foods also were analyzed to determine the cost of several key nutrients, including protein, fiber, potassium, vitamin A, vitamin C and folate. The nutrient content was obtained from the USDA Nutrient Data Laboratory, Standard Release 24. The nutrients selected for comparison were included because they are either "nutrients of concern" for children, adolescents and adults and/or are those commonly found in these foods.

*Note: Not all foods studied were available in all preparations. In those instances, they were omitted from the analysis in that form. Pinto beans were only available canned or dried. Pumpkin and tomatoes were only available in canned and fresh. Pears were not available frozen. Tuna was not available dried. Dried assorted mushrooms were substituted for dried white button mushrooms, which were not available.