Imagine a food-playoff system wherein watercress, a decent if unremarkable little vegetable long overshadowed by broccoli, kale, carrots, and many other veggies, not only makes it to the Sweet 16 but comes out on top. Improbable?
According to a new ranking put out by the Centers for Disease Control, watercress is the powerhouse vegetable among powerhouse fruits and vegetables (PFV). It's a ridiculous designation that highlights just how useless "superfoods" ratings actually are.
First, let's look into what constitutes a powerhouse fruit or vegetable anyway. The CDC defines PFVs as "foods providing, on average, 10 percent or more daily value per 100 kilocalories of 17 qualifying nutrients." So if a 100-calorie serving of a certain food has a higher than usual amount of 17 nutrients, including potassium, fiber, protein, calcium, and iron, the CDC calls it a superfood. Researchers ultimately identified 41 of these nutrient-dense eats.
While it's not a bad idea to provide people with a list of healthy foods, this ranked catalogue is deceiving. The fact that watercress won out over oranges, broccoli, blueberries, and many other nutritious fruits and veggies illuminates two big problems:
First, in order to get that daily dose of watercress goodness, one would have to eat 25 cups of it, watercress having only 4 calories per cup. "No one's going to eat 100 grams of watercress," points out registered dietitian Katherine Isacks. "Just because it scores well doesn't mean it's practical."
Second, the CDC created a very narrow definition of what makes a food "super." Aside from issues of practicality, cost, and availability (watercress being pricier and harder to find than fellow superfoods carrots, squash, or grapefruit), other fruits and vegetables that are high in healthy phytonutrients and antioxidants didn't even make the cut. "Certain foods are penalized because they don't have a lot of these 17 nutrients," says registered dietitian Janet Helm of Nutrition Unplugged. "Very few vegetables can be jacks of all trades. There's no one fruit or vegetable that can deliver everything."
Helm has a few more choice words against these superfoods rankings. "I don't want this turned into 'Watercress is the new kale.' Although, really, as fatigued as I am with superfoods in general and these sorts of lists, there's not a bad fruit or vegetable—even if you're eating what's trendy."
So the real message here is this: screw the lists. Just eat more fruits and vegetables. "People will look at this [list] and say, 'What can I eat most of to get the most value for my calories,' says Heather Mangieri, a registered dietitian who specializes in sports dietetics. "Most consumers understand eating more vegetables is good. And I don't care what vegetable you eat, eat more of it. But look for a variety. That's what's important."