The Pros and Cons of “Processed Foods”
Not all processed foods are products to avoid. Here’s how to shop smart.
The next time someone rails against the evils of processed foods—such as proponents of the current “eating clean” fad—keep in mind that “processed foods” include:
- pasteurized milk
- prewashed lettuce and spinach
- canned beans
- “baby” carrots
- frozen and canned fish
- frozen fruits and vegetables
“You hear the term ‘processed food’ thrown around a lot these days, but you have to use common sense,” says Alice H. Lichtenstein, DSc, director of Tufts’ HNRCA Cardiovascular Nutrition Laboratory and executive editor of the Health & Nutrition Letter. “Even though technically ‘processed,’ pasteurized milk is safer than unpasteurized. Frozen produce, because it’s picked and frozen at the peak of freshness and ‘processed’ quickly, is as nutritious as fresh or in many cases more so. And if the convenience of ripping open a bag of baby-cut carrots makes you more likely to snack on them instead of chips or cookies while preparing dinner, that’s good fallout from processing.”
The US government defines “processed food” as “any food other than a raw agricultural commodity that has been subject to processing, such as canning, cooking, freezing, dehydration or milling.” Basically, that encompasses anything that has been altered from its original state beyond basic cleaning, brushing off dirt or removing leaves and stems. Even polished apples might be considered “processed,” and peeled or pre-cut fruits are definitely processed, however minimally. Any food that contains added salt, sugar, fat or additives or that has been mixed with other ingredients is considered processed, too. (That includes something like iodized salt, which has essentially wiped out goiter in the US.)
SAFETY AND NUTRIENTS: Apart from the advantages of convenience, processed food may be safer because contaminants have been removed (as in prewashed salad greens) or destroyed (as in pasteurized milk). Many processed foods also last longer without spoiling or becoming unsafe to eat.
Cutting and chopping produce can make some nutrients more available to the body by breaking down cell walls (though it speeds deterioration of water-soluble nutrients). So can heating, including the heat of canning, although heat also destroys some vitamins: The lycopene in canned tomatoes and tomato sauces is more accessible than in fresh, uncooked tomatoes.
Freezing not only locks in the nutrients of fruits and vegetables, but makes them affordably available all year long. Frozen vegetables are easy to quickly add to a stir-fry or stew, making it more likely fruit and vegetable recommendations will be met.
Freezing makes seafood more readily available, too. Unless you live near a coast, flash-frozen seafood is the best way to meet recommendations to eat two fish meals per week.
DIETARY DOWNSIDES: Not all the news about processed foods is good, of course, or nutrition experts wouldn’t spend so much time warning against them. Food that has been highly modified, with lots of added calories, including saturated fat, sugars and starches, has helped fuel the obesity epidemic and Americans’ worst eating habits.
A recent study, in fact, sought to quantify the contribution of moderately and highly processed foods to unhealthy dietary trends. Published in the American Journal of Clinical Nutrition, the study analyzed purchases of packaged goods for 157,142 US households from 2000-2012, classifying the contents of more than 1.2 million products. Jennifer M. Poti, PhD, of the University of North Carolina, and colleagues concluded that highly processed foods and beverages contributed 61% of the calorie intake of those households. Moderately processed items added another 16%, for a total of more than three-quarters of average calories. Highly processed and ready-to-eat products were significantly higher in saturated fat, sugar and sodium.
What counts as a “highly processed” product? There is no official government definition. Poti and colleagues used the definition of “multi-ingredient industrially formulated mixtures processed to the extent that they are no longer recognizable as their original plant or animal source.” Among the highly processed foods that contributed the most calories in the study were refined breads, grain-based desserts, sugar-sweetened beverages, salty snacks, candy, ready-to-eat cereals, ice cream, mayonnaise, salad dressing, pasta sauce, ketchup, margarine and shortening.
“Moderately processed” foods were defined two ways: those processed only by the addition of flavors but otherwise recognizable as their original plant or animal sources, and grain products such as whole-wheat breads and cereals with no added sweeteners or fat.
But a 2012 study of processed foods in the US diet led by Heather Eicher-Miller, PhD, of Purdue University suggested that processing is not a major determinant of a food’s contribution to dietary intake. That study concluded that “no processing category contains foods that are uniformly ‘healthy’ or ‘unhealthy.’”