Does Michelle Obama's war on obesity give short shrift to canned and frozen produce?

The state of the universe.
March 25 2010 3:21 PM

Not So Fresh

Does Michelle Obama's war on obesity give short shrift to canned and frozen produce?

Family cooking with vegetables. Click image to expand.
They look good, but are fresh veggies better for you?

"We've heard the statistics," writes Michelle Obama in her celebrity freelance gig for the March 22 issue of Newsweek. "One third of all kids in this country are either overweight or obese."Our youth are bigger and fatter than ever before —so what can we do about it? America's first mom has a plan, laid out in all-caps across the cover of the magazine: "FEED YOUR CHILDREN WELL." That means more whole grains, and less fat, sugar, and salt. It also means renewing our commitment to an age-old parenting precept: Eat your (fruits and) vegetables.

Daniel Engber Daniel Engber

Daniel Engber (@danengber) is a columnist for Slate. Send him an email at danengber@yahoo.com.

The guarantee of fresh produce in corner stores and school cafeterias has become a major goal of the war on obesity. We're already pushing farmers-market produce on low-income moms through the WIC program; now the White House has proposed $400 million a year for the eradication of "food deserts," defined by the secretary of agriculture as places where there's no access to fresh fruits and vegetables. Similar efforts are happening on a local scale: In New York City, for example, those on food stamps receive what amounts to a 40-percent discount on purchases from the green market, and grocers get tax credits and zoning incentives for selling fresh fruits and vegetables.

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Meanwhile, public health advocates complain that two-fifths of the nation's schools don't provide students with fresh produce on a daily basis. This week the Senate agriculture committee starts work on a bill to add $500 million a year to the lunch kitty, including funds for farm-to-school programs that send locally grown fruits and vegetables to school cafeterias. The new law would also dole out for school gardens, so kids can grow fresh produce for themselves.

Take a close look at the policy approaches listed above—farm-to-school programs, foodstamp discounts at green markets, and tax credits for grocery produce sections—each one is designed in large part to improve access to fresh produce. Not just any old produce, but fresh produce—unprocessed, uncooked, and untarnished by industrial machinery. School cafeterias already have frozen carrots and canned peaches. Our kids need fresh, fresh, fresh!

This strategy may seem unobjectionable. Why challenge this devotion to plants just tugged from the warm soil? A single-minded focus on fresh produce distracts us from the bigger problem: Our children are suffering from a lack of any fruits or vegetables whatsoever. Canned, frozen, dried, juiced—anything would help. Here's a simple dictum for public health, endorsed by nutritionists across the land: All forms of fruits and vegetables matter.

I know it sounds weird. A crisp salad of watercress and red onions must be more wholesome than, say, a pile of defrosted spinach and some canned beets, right?  Not according to any practical measure of nutritive content. Researchers have been studying this question for a long time, and the results are clear. According to a 2007 review paper from UC-Davis, * levels of vitamins, minerals and fiber are similar across fresh, canned, and frozen products. It's worth noting that the Davis study, and some others like it, were conducted with grants from the canned-food industry—but their findings have not been discredited.

In fact, most public health experts will tell you that frozen produce can be more nutritious than locally grown crudités. That's because processed foods are harvested at peak quality then packaged so as to arrest the natural processes of respiration and spoilage. A few nutrients may be lost—canning is particularly hard on vitamin C, for one—but the rest are more or less locked in. A fresh bunch of spinach, by contrast, starts bleeding vitamins from the moment it comes out of the ground, and continues to wilt over the course of its long journey to your refrigerator.

There are some caveats. Not all fresh vegetables shed nutrients at the same rate: A recent USDA study found that the fluorescent lights in a grocery store can keep photosynthesis going in bagged spinach and slow the loss of ascorbic acid, folate, and other vitamins. (Packages buried at the bottom of a display case don't fare as well.) Cooking also makes a difference: A paper published two weeks ago showed that the nutrients in fresh broccoli, cauliflower, and Brussels sprouts are more resilient to the stovetop or the microwave than the ones in frozen samples. Canned vegetables often come with added sodium, and canned fruits may be packed in sugar syrup. Still, we'd be foolish to imagine that fresh produce is wildly more desirable—from a dietary perspective—than what's been frozen and canned.

Food activists who recognize this fact offer a second argument for going fresh. Bright colors and glistening leaves make for a more appealing product, they say, and one that children and their parents are more likely to buy and eat. According to food-policy guru Marion Nestle, that's why unprocessed fruits and vegetables get promoted. A package of frozen peas may be "about as or more nutritious than fresh, but [they] don't taste nearly as good."

Now we're into something more complicated than the nutritional makeup of our food (which is already very complicated). How do you measure relative deliciousness? I'm sure most readers will take it as a given that fresh, raw, or even organic fruits and vegetables have more flavor—more good flavor, that is—than canned or frozen. It's certainly true they taste different. But how are we to know what's gustatory fact and what's just culture? Surely our taste for fresh produce is colored—or even dictated—by history and fashion. I'm enough a product of my environment to be outraged by the sight of canned mushrooms on my brick-oven pizza. Yet I also happen to like the tinny, squeaky taste of canned string beans. Others may have more consistent preferences than mine—who's right and who's wrong?