Kale has been the poster child of healthy eating for years. But when researchers ranked fruits and vegetables based on how many key nutrients they contain per calorie, kale didn’t come in first. It didn’t even make the top 10. The winner is a vegetable that most people rarely buy.
In brief
- A study published by the CDC journal ranked 41 “powerhouse” fruits and vegetables based on their nutritional density.
- Watercress comes in first place, with a perfect score of 100.
- Chinese cabbage, chard, beet greens and spinach followed.
- Kale placed 15th and several popular foods didn’t qualify at all.
The study
In 2014, researcher Jennifer Di Noia published a study in Prevent chronic diseasesa review from the Centers for Disease Control and Prevention. She analyzed 47 foods and scored each of them on 17 important health nutrients, including potassium, fiber, protein, calcium, iron, folic acid, zinc, and vitamins A, B6, B12, C, D, E, and K. The score reflects how much of these nutrients a food provides per 100 calories.
Foods scoring 10 or higher were classified as “powerful” fruits and vegetables, consistent with the FDA threshold for a “good source” of a nutrient (10% of the daily value). Forty-one were selected. Nutrition data came from the USDA National Nutrient Database, using raw forms of each food.
The top 10
- 1. Watercress: 100
- 2. Chinese cabbage: 91.99
- 3. Chard: 89.27
- 4. Beet Greens: 87.08
- 5. Spinach: 86.43
- 6. Chicory: 73.36
- 7. Leaf lettuce: 70.73
- 8. Parsley: 65.59
- 9. Romaine lettuce: 63.48
- 10. Green cabbage: 62.49
Kale scored 49.07, ranking 15th among the 41 top foods.
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The surprises
Leafy greens dominate the list because they provide lots of nutrients for very few calories. On the other hand, some foods that many people consider superfoods are not considered power foods in this ranking: raspberries, tangerines, cranberries, garlic, onions, and blueberries. Apples, bananas, corn, and potatoes were used as low-performing comparison foods. This doesn’t make them bad, just less dense in these 17 nutrients per calorie. Potatoes remain a staple food, as long as you store them correctly.
How to eat more watercress
Watercress is often sold in bunches or small bags near salad greens, and its delicate leaves are best eaten fresh. It has a peppery taste, a bit like arugula. It can be used raw in salads and sandwiches, mixed into soups or added at the last minute to a stir-fry. Since the study used raw foods, cooking may change some values.
The limit
The author herself lists the limitations of the study: only selected food groups were included, phytochemicals could not be counted, validation was preliminary and cooking was not taken into account. A calorie ranking also favors very low-calorie green vegetables. The best diet remains one that is varied. And in the kitchen, peels and leftovers also have their uses, as boiled lemon zest with ginger.
That’s the thing.
Gn Health
