What’s so bad about processed foods?

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Dear Cecil: Why are processed foods bad? If I take a chicken breast and process it into a paste, is it worse for my health than if I ate the chicken whole? Please help before I get butt cancer from a chicken nugget! Jim Huff


Illustration by Slug Signorino

Cecil replies:

Let’s get the bad news out of the way, Jim. Last month a big French study came out that tracked the diets of some 100,000 participants to better understand the relationship between cancer and what its authors refer to as “ultra-processed foods,” characterized by “a higher content of total fat, saturated fat, and added sugar and salt, along with a lower fibre and vitamin density.” And though butt cancer wasn’t named as a specific threat, the findings did in fact link a 10 percent proportional increase in consumption of such food with a 10 percent-plus rise in cancer risk overall. Further research is needed, but — brace yourselff — it’s looking like chicken nuggets may not be amazing for your health.

The good news? Your skepticism regarding any categorical condemnation of “processed foods” is entirely warranted. This reality, in fact, is a big part of the organizing principle underlying the French research — about which more below. Not only is there nothing inherently bad about processed foods, the phrase itself is so capacious and variously defined as to be basically meaningless. Unless you’re picking grapes off the vine, you’re eating food that’s been processed somehow or other: milk is pasteurized; wheat is ground; salad mix is washed. A 2000 article in the British Medical Bulletin defined food processing as “any procedure undergone by food commodities after they have left the primary producer, and before they reach the consumer” — mere refrigeration counts.

That’s a distinctly capitalist formulation, but by most definitions, humans have engaged in food processing for millennia. Cooking with fire is the ur-processing method, and our ancestors may have been at it 1.5 million years ago. Other techniques have involved creative ways to unlock nutrition in food or extend its shelf life. In the former category, see e.g. nixtamalization, the practice of treating maize with limestone or lye, which helped the Aztecs and Mayans get more protein and disease-preventing vitamins in their diet. For the latter, see basically any form of fermentation: milk turned into cheese and yogurt is the most widespread, but you’ve also got Korean kimchi (fermented vegetables), Nigerian ogi (fermented grains), and assorted smelly preserved-fish dishes encountered at high latitudes, including Swedish surströmming, Norwegian rakfisk, and “stinkheads,” which the Yupik people of Alaska prepare by burying salmon heads in the ground and leaving them to age.

Many methods of fermenting, curing, etc. rely on salt — an extremely consequential ingredient in this realm, particularly prior to refrigeration. But salt took its own place among processed foods early in the 20th century when we began fortifying it with iodine, essential for thyroid function. In coastal regions, iodine in the soil makes its way into the groundwater, but further inland you won’t find enough of it occurring naturally, and till the 1920s there was a huge swath of the northern U.S., stretching from the Appalachians to the Cascades — the “goiter belt,” they called it — where between a quarter and 70 percent of all kids displayed visibly enlarged thyroids. Just as adding vitamin D to milk took care of our national rickets problem, iodized salt pretty much wiped out goiter, plus some serious developmental disorders also associated with iodine deficiency. It’s been floated as one factor behind what’s known as the Flynn effect: the three-point-per-decade rise in IQ observed in developed countries over the 20th century.

So yeah, food processing has done a thing or two for humanity. We haven’t even touched on the fact that urbanization would have been a hell of a lot harder without food preserved for shipping from the hinterlands, or that the zillion hours of food-prep labor we’ve saved by not making everything from scratch would have fallen disproportionately on women’s shoulders.

Do “processed foods,” then, deserve their bad rap? Answer: no, which is something public-health experts are coming around on. The French study discussed above uses a four-category food-classification system proposed by Brazilian researchers in 2010 that separates harmless or beneficial food processing from the problematic sort. NOVA, as the scheme’s called, distinguishes between unprocessed or minimally processed foods (e.g. meats, plants); processed culinary ingredients (sugar, vegetable oils); processed foods (canned vegetables, cured meats); and, finally, ultra-processed foods, defined as “industrial formulations with five or more and usually many ingredients,” including “substances not commonly used in culinary preparations.”

And yes, the NOVA authors list “poultry and fish ‘nuggets’” in this last group. Again, one thing typifying ultra-processed foods is low nutrient density and high energy density, what with all that added fat and carbs. Those traits are much of (a) the real problem, as far as healthy eating goes, and (b) why Doritos taste so good. But I hope by now you’re distinguishing this kind of stuff from your homemade chicken paste, which isn’t the kind of processed food you need to worry about. Appealing as it sounds, though, I’m afraid I’ve got dinner plans.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.