Not kale, not blueberries: the peppery green that topped a CDC-published ranking, and how to grow it at home. Every few years, a new superfood takes over grocery aisles and social feeds. Kale had its moment, then blueberries, then avocado. But when a researcher ranked fruits and vegetables by how many nutrients they deliver per calorie, the winner was a modest leaf most people know only as a garnish.
It is watercress, and it scored a perfect 100.
The Study Behind the Ranking
In 2014, researcher Jennifer Di Noia published “Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach” in Preventing Chronic Disease, a journal published by the Centers for Disease Control and Prevention.
She scored 47 fruits and vegetables on 17 nutrients considered important for public health, including fiber, potassium, iron, calcium, folate and vitamins A, C and K. The score measured how much of these nutrients each food provides per 100 calories. Foods that delivered, on average, at least 10 percent of the daily value per 100 calories qualified as “powerhouse” foods. Forty-one of the 47 made the cut.
The Top Five
Watercress came first with a score of 100. It was followed by Chinese cabbage at 91.99, chard at 89.27, beet greens at 87.08 and spinach at 86.43. Chicory, leaf lettuce, parsley, romaine and collard greens completed the top 10.
Some popular “superfoods” did not qualify at all. Raspberries, tangerines, cranberries, garlic, onions and blueberries fell below the threshold. That does not mean they are unhealthy, only that they deliver fewer of those specific nutrients per calorie.
What Makes Watercress So Dense
Watercress is extremely low in calories and rich in water, so every calorie carries a lot of nutrition. It is a standout source of vitamin K, important for blood clotting and bone health, and also provides vitamin C and vitamin A. As a member of the cruciferous family, like broccoli and cabbage, it also contains plant compounds that researchers continue to study.
One note: because of its vitamin K content, people taking blood thinners such as warfarin should keep their intake of leafy greens consistent and talk to their doctor.
Easy Ways to Eat It
Watercress has a fresh, peppery bite, a little like arugula. Toss it into salads with pears, walnuts and goat cheese. Add a handful to sandwiches and wraps instead of lettuce. Stir it into soups at the very end of cooking, or blend it into a classic watercress and potato soup. It also makes a vibrant pesto with olive oil, garlic, Parmesan and nuts, perfect for pasta or grilled fish.
How to Grow It on a Windowsill
Watercress naturally grows in running water, so the secret is moisture. Fill a pot with drainage holes with moist potting mix, sprinkle the seeds on the surface and press them in lightly. Place the pot in a saucer or tray of water so the soil never dries out, and change the water every few days to keep it fresh.
Keep it on a bright windowsill out of harsh afternoon sun, at cool to moderate room temperature. Seedlings appear within a week or two, and you can start snipping leaves after a few weeks. Cut stems just above a leaf node, and the plant will keep producing.
Science named watercress the most nutrient-dense of the foods it studied, and you can grow it on your windowsill. It may be the easiest healthy upgrade to add to your kitchen this fall.