"Fresh good. Packaged bad." The clean-eating mantra makes perfect sense, but it turns out your supermarket's produce section never got the memo.
In two recent studies from Britain, researchers purchased a half dozen different kinds of fruit and vegetables, all of which came in two varieties: fresh and frozen. After buying them—and then having them chill out in either a fridge or freezer for three days—researchers conducted 40 tests to compare their nutritional content.
Turns out the frozen varieties were richer in health-boosting vitamins and antioxidants. In fact, frozen broccoli had four times more beta-carotene than its fresh counterpart, while frozen carrots had three times more lutein and double the beta-carotene as well as greater levels of vitamin C and polyphenols. A few produce picks (raspberries and peas, for example) performed about the same across the board whether they were fresh or frozen, but they were exceptions to what could become the new rule of produce: go frozen.
What gives? While it's true that foods gradually lose nutrients as they move through the supply chain, that chain is far longer for fresh produce than their "just-picked" stickers suggest. Fruits and vegetables are regularly held in storage for up to a month before you ever see them. Plus, according to study author Graham Bonwick Ph.D., a professor of applied biology at the University of Chester, once they hit your fridge the nutritional loss escalates. That's probably due to plants' continuing metabolic activity and how cells react to oxygen and even exposure to artificial dark-light cycles.
Case in point: A recent study from Rice University and the University of California at Davis found that the fluorescent lights of supermarkets and the perpetual darkness of your fridge can screw with fruits and vegetables' circadian clocks so that they excrete fewer glucosinolates—compounds with cancer-fighting properties.
That's where sub-zero temps come in handy. "Produce's degradation reactions are very much slowed by lowering the temperature to freezing levels," Bonwick says. "Furthermore, when you freeze produce, the water present in the cells of the food is locked up as ice, slowing or preventing these processes that require the presence of free water." Plus, since the produce in the freezer section was frozen solid almost immediately after being plucked, it's preserved at its nutritional peak.
Think of it as cryogenic freezing. Your food stays young until you thaw it out—and so do you. The antioxidants and nutritional compounds saved by freezing produce are critical to fighting free radicals, weight gain, preventing chronic diseases, and even obtaining blemish-free skin and a thick head of hair.
So unless you plan to take up gardening, opt for frozen varieties whenever possible—especially as winter approaches. If you do buy fresh—and we know that some picks just taste better that way—pop your plants in the freezer post-purchase or just eat them ASAP. After all, if you're going to eat your veggies, you might as well get something out of it.
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