Globe-trotting Papayas: How Far Has Your Food Traveled?
Perhaps you consider yourself a socially and environmentally responsible individual: you separate all your recyclables (you even wash out all the containers), turn off the water when you brush your teeth, and buy shampoo packaged in postconsumed plastic.
Now you're about to sit down to a well-earned "fresh" fruit salad of papayas, strawberries, and grapes.
But the papayas are from Mexico, the strawberries are imported from Ecuador, and the grapes from Chile. How environmentally responsible is it if your food has traveled a greater distance than you have on any particular day? And how appreciable is its actual nutrient content?
From Field to Table
It's been estimated that food eaten in this country travels an average of 1,300 miles from the farm to the dinner table. That's a year-round average. But a papaya or other produce that rides on one truck from Northern Mexico to Chicago travels about 1,700 miles, costing close to $5,000. That same truck travels approximately 2,000 miles from Mexico to Seattle at a cost of about $6,000. If that papaya lands in Boston, it will have traveled 2,800 miles and cost more than $8,000. This is an economic and environmental concern; at this rate, fuel and local agricultural resources could run out for future generations.
So what are your options? Native Americans in land-locked Montana ate 60 species of plants and tree products. The early Pilgrims established their roots subsisting on spoiled squash and sprouted spuds in the cold months. With no cross-continental transportation, Northwesterner pioneers existed on apples and some seafood. And in the Midwest, settler families ate mainly brown bread and potatoes through the long winters.
Fortunately, our options today are somewhat more flexible—there are local alternatives. For instance, fresh winter greenhouse lettuce grown in Maine costs only $450 to truck to Boston. Aside from being less expensive, the environment is also protected, because food travels shorter distances and uses less fossil fuels. In addition, local farmers are supported, keeping local farmland productive and allowing farmers to expand and provide a greater variety of products for the future.
A year-round guide to local fresh produce can be obtained from your state's Department of Agriculture or county Cooperative Extension Service office. However, in much of the winter and early spring, the only local fresh produce available in northern latitudes falls in the apple, pear, root vegetable, cabbage, onion, or squash families. If you want other types of fresh produce at this time of year, one option is to can or freeze your own when they're in-season. But this represents a significant cash outlay for canning and freezing equipment and a comprehensive knowledge of sanitation and storage techniques.
There is another, simpler alternative. The simple act of navigating your grocery cart through the frozen and canned produce section of your market can help save the earth and improve your nutrition! Frozen fruit and vegetables are shipped directly from the fields and orchards in which they are grown to a processor near the field. After they have been frozen or canned, they are preserved at the processor until a large bulk shipment can be made. Perishable fresh produce, on the other hand, needs to get to its destination quickly and must be shipped in smaller shipments and great distances, especially off-season. As mentioned, this is a very uneconomical process.
Fresh produce is shipped quickly enough to prevent spoilage. But its nutrient content may be compromised. The longer fruits and vegetables are in transition, the more nutrients are oxidized into the air. The average time from field to your fruit or salad bowl is about 10-14 days. In contrast, produce that is frozen or canned sits only a couple of hours before its freshness and nutrients are locked in by freezing or canning.
Nutrient Content Affected by Travel and Processing
The differences in the nutrition content of fresh versus frozen and canned foods are significant. Dr. Barbara Klein, a professor of foods and nutrition at the University of Illinois, found that frozen green beans retain 77% of their vitamin C content. On the other hand, "fresh" green beans that sit on a truck, wait on a loading dock at the supermarket, and then languish in your refrigerator, retain only 36% of their vitamin C content.
Klein found a similar scenario with a can of pumpkin. One-half cup of canned pumpkin has about 300% of the recommended dietary intake (RDI) for the antioxidant beta carotene, a precursor of vitamin A. The same amount of fresh, cooked pumpkin contains less than 20% of the RDI for beta carotene. Part of the reason for the dramatic difference is that canned pumpkin contains less water than fresh; the canned version is a more concentrated source of beta carotene. Still, the potency of the nutrients in this and other canned vegetables are substantially higher than "fresh" ones that travel hundreds of miles, losing nutrients along the way.
Ever notice that despite that fact that your frozen strawberries or canned pumpkin may be months old, that they retain their bold colors when you do decide to use them? The reason, Dr. Klein explains, is that food processors often choose the brightest, most vivid colored produce right from the field. These fruits and vegetables are not only more pleasing to consumers, but also contain the greatest concentration of nutrients. These deeper hues signify a richer nutrient content.
The nutritional value of some foods is improved with canning. Lycopene, an antioxidant found in tomatoes, is actually enhanced by the canning process. This compound, along with other antioxidants, may help protect cells from the damaging effects of environmental and ingested toxins that can lead to heart disease and cancer. They may also ward off effects of the aging process. Lycopene is found naturally in tomatoes, but is better absorbed by the body from canned tomato products such as tomato paste, sauce, and chopped tomatoes.
The Drawbacks to Frozen and Canned Produce
One of the major drawbacks to using frozen or canned vegetables is that extra sodium and fat can sneak in. Those who need to watch their salt intake should look for low-sodium varieties of canned vegetables. Most vegetable-sauce combinations are high in fat; you can create your own low-fat sauces with honey, flavored vinegars, herbs and spices, or low-fat cheeses. Although most frozen vegetables are packaged "au natural," you should check the label to be sure.
Summer is an excellent time to frequent local farmers' markets for fresh, nontransported produce. And in the winter you can treat yourself to a sliced papaya for a little extra sunshine. Just think about canned, frozen, or locally produced options before you do, and don't eat from the equator every weekday this winter. It's not just about saving natural resources—it's about your personal health and nutrition.
Fruits and Veggies: More Matters
United States Department of Agriculture
Last reviewed July 2007 by Marcin Chwistek, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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